LCOV - code coverage report
Current view: top level - src/backend/postmaster - autovacuum.c (source / functions) Hit Total Coverage
Test: PostgreSQL 19devel Lines: 816 982 83.1 %
Date: 2025-09-01 09:18:58 Functions: 32 33 97.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * autovacuum.c
       4             :  *
       5             :  * PostgreSQL Integrated Autovacuum Daemon
       6             :  *
       7             :  * The autovacuum system is structured in two different kinds of processes: the
       8             :  * autovacuum launcher and the autovacuum worker.  The launcher is an
       9             :  * always-running process, started by the postmaster when the autovacuum GUC
      10             :  * parameter is set.  The launcher schedules autovacuum workers to be started
      11             :  * when appropriate.  The workers are the processes which execute the actual
      12             :  * vacuuming; they connect to a database as determined in the launcher, and
      13             :  * once connected they examine the catalogs to select the tables to vacuum.
      14             :  *
      15             :  * The autovacuum launcher cannot start the worker processes by itself,
      16             :  * because doing so would cause robustness issues (namely, failure to shut
      17             :  * them down on exceptional conditions, and also, since the launcher is
      18             :  * connected to shared memory and is thus subject to corruption there, it is
      19             :  * not as robust as the postmaster).  So it leaves that task to the postmaster.
      20             :  *
      21             :  * There is an autovacuum shared memory area, where the launcher stores
      22             :  * information about the database it wants vacuumed.  When it wants a new
      23             :  * worker to start, it sets a flag in shared memory and sends a signal to the
      24             :  * postmaster.  Then postmaster knows nothing more than it must start a worker;
      25             :  * so it forks a new child, which turns into a worker.  This new process
      26             :  * connects to shared memory, and there it can inspect the information that the
      27             :  * launcher has set up.
      28             :  *
      29             :  * If the fork() call fails in the postmaster, it sets a flag in the shared
      30             :  * memory area, and sends a signal to the launcher.  The launcher, upon
      31             :  * noticing the flag, can try starting the worker again by resending the
      32             :  * signal.  Note that the failure can only be transient (fork failure due to
      33             :  * high load, memory pressure, too many processes, etc); more permanent
      34             :  * problems, like failure to connect to a database, are detected later in the
      35             :  * worker and dealt with just by having the worker exit normally.  The launcher
      36             :  * will launch a new worker again later, per schedule.
      37             :  *
      38             :  * When the worker is done vacuuming it sends SIGUSR2 to the launcher.  The
      39             :  * launcher then wakes up and is able to launch another worker, if the schedule
      40             :  * is so tight that a new worker is needed immediately.  At this time the
      41             :  * launcher can also balance the settings for the various remaining workers'
      42             :  * cost-based vacuum delay feature.
      43             :  *
      44             :  * Note that there can be more than one worker in a database concurrently.
      45             :  * They will store the table they are currently vacuuming in shared memory, so
      46             :  * that other workers avoid being blocked waiting for the vacuum lock for that
      47             :  * table.  They will also fetch the last time the table was vacuumed from
      48             :  * pgstats just before vacuuming each table, to avoid vacuuming a table that
      49             :  * was just finished being vacuumed by another worker and thus is no longer
      50             :  * noted in shared memory.  However, there is a small window (due to not yet
      51             :  * holding the relation lock) during which a worker may choose a table that was
      52             :  * already vacuumed; this is a bug in the current design.
      53             :  *
      54             :  * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
      55             :  * Portions Copyright (c) 1994, Regents of the University of California
      56             :  *
      57             :  *
      58             :  * IDENTIFICATION
      59             :  *    src/backend/postmaster/autovacuum.c
      60             :  *
      61             :  *-------------------------------------------------------------------------
      62             :  */
      63             : #include "postgres.h"
      64             : 
      65             : #include <signal.h>
      66             : #include <sys/time.h>
      67             : #include <unistd.h>
      68             : 
      69             : #include "access/heapam.h"
      70             : #include "access/htup_details.h"
      71             : #include "access/multixact.h"
      72             : #include "access/reloptions.h"
      73             : #include "access/tableam.h"
      74             : #include "access/transam.h"
      75             : #include "access/xact.h"
      76             : #include "catalog/dependency.h"
      77             : #include "catalog/namespace.h"
      78             : #include "catalog/pg_database.h"
      79             : #include "catalog/pg_namespace.h"
      80             : #include "commands/vacuum.h"
      81             : #include "common/int.h"
      82             : #include "lib/ilist.h"
      83             : #include "libpq/pqsignal.h"
      84             : #include "miscadmin.h"
      85             : #include "nodes/makefuncs.h"
      86             : #include "pgstat.h"
      87             : #include "postmaster/autovacuum.h"
      88             : #include "postmaster/interrupt.h"
      89             : #include "postmaster/postmaster.h"
      90             : #include "storage/aio_subsys.h"
      91             : #include "storage/bufmgr.h"
      92             : #include "storage/ipc.h"
      93             : #include "storage/latch.h"
      94             : #include "storage/lmgr.h"
      95             : #include "storage/pmsignal.h"
      96             : #include "storage/proc.h"
      97             : #include "storage/procsignal.h"
      98             : #include "storage/smgr.h"
      99             : #include "tcop/tcopprot.h"
     100             : #include "utils/fmgroids.h"
     101             : #include "utils/fmgrprotos.h"
     102             : #include "utils/guc_hooks.h"
     103             : #include "utils/injection_point.h"
     104             : #include "utils/lsyscache.h"
     105             : #include "utils/memutils.h"
     106             : #include "utils/ps_status.h"
     107             : #include "utils/rel.h"
     108             : #include "utils/snapmgr.h"
     109             : #include "utils/syscache.h"
     110             : #include "utils/timeout.h"
     111             : #include "utils/timestamp.h"
     112             : 
     113             : 
     114             : /*
     115             :  * GUC parameters
     116             :  */
     117             : bool        autovacuum_start_daemon = false;
     118             : int         autovacuum_worker_slots;
     119             : int         autovacuum_max_workers;
     120             : int         autovacuum_work_mem = -1;
     121             : int         autovacuum_naptime;
     122             : int         autovacuum_vac_thresh;
     123             : int         autovacuum_vac_max_thresh;
     124             : double      autovacuum_vac_scale;
     125             : int         autovacuum_vac_ins_thresh;
     126             : double      autovacuum_vac_ins_scale;
     127             : int         autovacuum_anl_thresh;
     128             : double      autovacuum_anl_scale;
     129             : int         autovacuum_freeze_max_age;
     130             : int         autovacuum_multixact_freeze_max_age;
     131             : 
     132             : double      autovacuum_vac_cost_delay;
     133             : int         autovacuum_vac_cost_limit;
     134             : 
     135             : int         Log_autovacuum_min_duration = 600000;
     136             : 
     137             : /* the minimum allowed time between two awakenings of the launcher */
     138             : #define MIN_AUTOVAC_SLEEPTIME 100.0 /* milliseconds */
     139             : #define MAX_AUTOVAC_SLEEPTIME 300   /* seconds */
     140             : 
     141             : /*
     142             :  * Variables to save the cost-related storage parameters for the current
     143             :  * relation being vacuumed by this autovacuum worker. Using these, we can
     144             :  * ensure we don't overwrite the values of vacuum_cost_delay and
     145             :  * vacuum_cost_limit after reloading the configuration file. They are
     146             :  * initialized to "invalid" values to indicate that no cost-related storage
     147             :  * parameters were specified and will be set in do_autovacuum() after checking
     148             :  * the storage parameters in table_recheck_autovac().
     149             :  */
     150             : static double av_storage_param_cost_delay = -1;
     151             : static int  av_storage_param_cost_limit = -1;
     152             : 
     153             : /* Flags set by signal handlers */
     154             : static volatile sig_atomic_t got_SIGUSR2 = false;
     155             : 
     156             : /* Comparison points for determining whether freeze_max_age is exceeded */
     157             : static TransactionId recentXid;
     158             : static MultiXactId recentMulti;
     159             : 
     160             : /* Default freeze ages to use for autovacuum (varies by database) */
     161             : static int  default_freeze_min_age;
     162             : static int  default_freeze_table_age;
     163             : static int  default_multixact_freeze_min_age;
     164             : static int  default_multixact_freeze_table_age;
     165             : 
     166             : /* Memory context for long-lived data */
     167             : static MemoryContext AutovacMemCxt;
     168             : 
     169             : /* struct to keep track of databases in launcher */
     170             : typedef struct avl_dbase
     171             : {
     172             :     Oid         adl_datid;      /* hash key -- must be first */
     173             :     TimestampTz adl_next_worker;
     174             :     int         adl_score;
     175             :     dlist_node  adl_node;
     176             : } avl_dbase;
     177             : 
     178             : /* struct to keep track of databases in worker */
     179             : typedef struct avw_dbase
     180             : {
     181             :     Oid         adw_datid;
     182             :     char       *adw_name;
     183             :     TransactionId adw_frozenxid;
     184             :     MultiXactId adw_minmulti;
     185             :     PgStat_StatDBEntry *adw_entry;
     186             : } avw_dbase;
     187             : 
     188             : /* struct to keep track of tables to vacuum and/or analyze, in 1st pass */
     189             : typedef struct av_relation
     190             : {
     191             :     Oid         ar_toastrelid;  /* hash key - must be first */
     192             :     Oid         ar_relid;
     193             :     bool        ar_hasrelopts;
     194             :     AutoVacOpts ar_reloptions;  /* copy of AutoVacOpts from the main table's
     195             :                                  * reloptions, or NULL if none */
     196             : } av_relation;
     197             : 
     198             : /* struct to keep track of tables to vacuum and/or analyze, after rechecking */
     199             : typedef struct autovac_table
     200             : {
     201             :     Oid         at_relid;
     202             :     VacuumParams at_params;
     203             :     double      at_storage_param_vac_cost_delay;
     204             :     int         at_storage_param_vac_cost_limit;
     205             :     bool        at_dobalance;
     206             :     bool        at_sharedrel;
     207             :     char       *at_relname;
     208             :     char       *at_nspname;
     209             :     char       *at_datname;
     210             : } autovac_table;
     211             : 
     212             : /*-------------
     213             :  * This struct holds information about a single worker's whereabouts.  We keep
     214             :  * an array of these in shared memory, sized according to
     215             :  * autovacuum_worker_slots.
     216             :  *
     217             :  * wi_links     entry into free list or running list
     218             :  * wi_dboid     OID of the database this worker is supposed to work on
     219             :  * wi_tableoid  OID of the table currently being vacuumed, if any
     220             :  * wi_sharedrel flag indicating whether table is marked relisshared
     221             :  * wi_proc      pointer to PGPROC of the running worker, NULL if not started
     222             :  * wi_launchtime Time at which this worker was launched
     223             :  * wi_dobalance Whether this worker should be included in balance calculations
     224             :  *
     225             :  * All fields are protected by AutovacuumLock, except for wi_tableoid and
     226             :  * wi_sharedrel which are protected by AutovacuumScheduleLock (note these
     227             :  * two fields are read-only for everyone except that worker itself).
     228             :  *-------------
     229             :  */
     230             : typedef struct WorkerInfoData
     231             : {
     232             :     dlist_node  wi_links;
     233             :     Oid         wi_dboid;
     234             :     Oid         wi_tableoid;
     235             :     PGPROC     *wi_proc;
     236             :     TimestampTz wi_launchtime;
     237             :     pg_atomic_flag wi_dobalance;
     238             :     bool        wi_sharedrel;
     239             : } WorkerInfoData;
     240             : 
     241             : typedef struct WorkerInfoData *WorkerInfo;
     242             : 
     243             : /*
     244             :  * Possible signals received by the launcher from remote processes.  These are
     245             :  * stored atomically in shared memory so that other processes can set them
     246             :  * without locking.
     247             :  */
     248             : typedef enum
     249             : {
     250             :     AutoVacForkFailed,          /* failed trying to start a worker */
     251             :     AutoVacRebalance,           /* rebalance the cost limits */
     252             : }           AutoVacuumSignal;
     253             : 
     254             : #define AutoVacNumSignals (AutoVacRebalance + 1)
     255             : 
     256             : /*
     257             :  * Autovacuum workitem array, stored in AutoVacuumShmem->av_workItems.  This
     258             :  * list is mostly protected by AutovacuumLock, except that if an item is
     259             :  * marked 'active' other processes must not modify the work-identifying
     260             :  * members.
     261             :  */
     262             : typedef struct AutoVacuumWorkItem
     263             : {
     264             :     AutoVacuumWorkItemType avw_type;
     265             :     bool        avw_used;       /* below data is valid */
     266             :     bool        avw_active;     /* being processed */
     267             :     Oid         avw_database;
     268             :     Oid         avw_relation;
     269             :     BlockNumber avw_blockNumber;
     270             : } AutoVacuumWorkItem;
     271             : 
     272             : #define NUM_WORKITEMS   256
     273             : 
     274             : /*-------------
     275             :  * The main autovacuum shmem struct.  On shared memory we store this main
     276             :  * struct and the array of WorkerInfo structs.  This struct keeps:
     277             :  *
     278             :  * av_signal        set by other processes to indicate various conditions
     279             :  * av_launcherpid   the PID of the autovacuum launcher
     280             :  * av_freeWorkers   the WorkerInfo freelist
     281             :  * av_runningWorkers the WorkerInfo non-free queue
     282             :  * av_startingWorker pointer to WorkerInfo currently being started (cleared by
     283             :  *                  the worker itself as soon as it's up and running)
     284             :  * av_workItems     work item array
     285             :  * av_nworkersForBalance the number of autovacuum workers to use when
     286             :  *                  calculating the per worker cost limit
     287             :  *
     288             :  * This struct is protected by AutovacuumLock, except for av_signal and parts
     289             :  * of the worker list (see above).
     290             :  *-------------
     291             :  */
     292             : typedef struct
     293             : {
     294             :     sig_atomic_t av_signal[AutoVacNumSignals];
     295             :     pid_t       av_launcherpid;
     296             :     dclist_head av_freeWorkers;
     297             :     dlist_head  av_runningWorkers;
     298             :     WorkerInfo  av_startingWorker;
     299             :     AutoVacuumWorkItem av_workItems[NUM_WORKITEMS];
     300             :     pg_atomic_uint32 av_nworkersForBalance;
     301             : } AutoVacuumShmemStruct;
     302             : 
     303             : static AutoVacuumShmemStruct *AutoVacuumShmem;
     304             : 
     305             : /*
     306             :  * the database list (of avl_dbase elements) in the launcher, and the context
     307             :  * that contains it
     308             :  */
     309             : static dlist_head DatabaseList = DLIST_STATIC_INIT(DatabaseList);
     310             : static MemoryContext DatabaseListCxt = NULL;
     311             : 
     312             : /*
     313             :  * Dummy pointer to persuade Valgrind that we've not leaked the array of
     314             :  * avl_dbase structs.  Make it global to ensure the compiler doesn't
     315             :  * optimize it away.
     316             :  */
     317             : #ifdef USE_VALGRIND
     318             : extern avl_dbase *avl_dbase_array;
     319             : avl_dbase  *avl_dbase_array;
     320             : #endif
     321             : 
     322             : /* Pointer to my own WorkerInfo, valid on each worker */
     323             : static WorkerInfo MyWorkerInfo = NULL;
     324             : 
     325             : /* PID of launcher, valid only in worker while shutting down */
     326             : int         AutovacuumLauncherPid = 0;
     327             : 
     328             : static Oid  do_start_worker(void);
     329             : static void ProcessAutoVacLauncherInterrupts(void);
     330             : pg_noreturn static void AutoVacLauncherShutdown(void);
     331             : static void launcher_determine_sleep(bool canlaunch, bool recursing,
     332             :                                      struct timeval *nap);
     333             : static void launch_worker(TimestampTz now);
     334             : static List *get_database_list(void);
     335             : static void rebuild_database_list(Oid newdb);
     336             : static int  db_comparator(const void *a, const void *b);
     337             : static void autovac_recalculate_workers_for_balance(void);
     338             : 
     339             : static void do_autovacuum(void);
     340             : static void FreeWorkerInfo(int code, Datum arg);
     341             : 
     342             : static autovac_table *table_recheck_autovac(Oid relid, HTAB *table_toast_map,
     343             :                                             TupleDesc pg_class_desc,
     344             :                                             int effective_multixact_freeze_max_age);
     345             : static void recheck_relation_needs_vacanalyze(Oid relid, AutoVacOpts *avopts,
     346             :                                               Form_pg_class classForm,
     347             :                                               int effective_multixact_freeze_max_age,
     348             :                                               bool *dovacuum, bool *doanalyze, bool *wraparound);
     349             : static void relation_needs_vacanalyze(Oid relid, AutoVacOpts *relopts,
     350             :                                       Form_pg_class classForm,
     351             :                                       PgStat_StatTabEntry *tabentry,
     352             :                                       int effective_multixact_freeze_max_age,
     353             :                                       bool *dovacuum, bool *doanalyze, bool *wraparound);
     354             : 
     355             : static void autovacuum_do_vac_analyze(autovac_table *tab,
     356             :                                       BufferAccessStrategy bstrategy);
     357             : static AutoVacOpts *extract_autovac_opts(HeapTuple tup,
     358             :                                          TupleDesc pg_class_desc);
     359             : static void perform_work_item(AutoVacuumWorkItem *workitem);
     360             : static void autovac_report_activity(autovac_table *tab);
     361             : static void autovac_report_workitem(AutoVacuumWorkItem *workitem,
     362             :                                     const char *nspname, const char *relname);
     363             : static void avl_sigusr2_handler(SIGNAL_ARGS);
     364             : static bool av_worker_available(void);
     365             : static void check_av_worker_gucs(void);
     366             : 
     367             : 
     368             : 
     369             : /********************************************************************
     370             :  *                    AUTOVACUUM LAUNCHER CODE
     371             :  ********************************************************************/
     372             : 
     373             : /*
     374             :  * Main entry point for the autovacuum launcher process.
     375             :  */
     376             : void
     377         760 : AutoVacLauncherMain(const void *startup_data, size_t startup_data_len)
     378             : {
     379             :     sigjmp_buf  local_sigjmp_buf;
     380             : 
     381             :     Assert(startup_data_len == 0);
     382             : 
     383             :     /* Release postmaster's working memory context */
     384         760 :     if (PostmasterContext)
     385             :     {
     386         760 :         MemoryContextDelete(PostmasterContext);
     387         760 :         PostmasterContext = NULL;
     388             :     }
     389             : 
     390         760 :     MyBackendType = B_AUTOVAC_LAUNCHER;
     391         760 :     init_ps_display(NULL);
     392             : 
     393         760 :     ereport(DEBUG1,
     394             :             (errmsg_internal("autovacuum launcher started")));
     395             : 
     396         760 :     if (PostAuthDelay)
     397           0 :         pg_usleep(PostAuthDelay * 1000000L);
     398             : 
     399             :     Assert(GetProcessingMode() == InitProcessing);
     400             : 
     401             :     /*
     402             :      * Set up signal handlers.  We operate on databases much like a regular
     403             :      * backend, so we use the same signal handling.  See equivalent code in
     404             :      * tcop/postgres.c.
     405             :      */
     406         760 :     pqsignal(SIGHUP, SignalHandlerForConfigReload);
     407         760 :     pqsignal(SIGINT, StatementCancelHandler);
     408         760 :     pqsignal(SIGTERM, SignalHandlerForShutdownRequest);
     409             :     /* SIGQUIT handler was already set up by InitPostmasterChild */
     410             : 
     411         760 :     InitializeTimeouts();       /* establishes SIGALRM handler */
     412             : 
     413         760 :     pqsignal(SIGPIPE, SIG_IGN);
     414         760 :     pqsignal(SIGUSR1, procsignal_sigusr1_handler);
     415         760 :     pqsignal(SIGUSR2, avl_sigusr2_handler);
     416         760 :     pqsignal(SIGFPE, FloatExceptionHandler);
     417         760 :     pqsignal(SIGCHLD, SIG_DFL);
     418             : 
     419             :     /*
     420             :      * Create a per-backend PGPROC struct in shared memory.  We must do this
     421             :      * before we can use LWLocks or access any shared memory.
     422             :      */
     423         760 :     InitProcess();
     424             : 
     425             :     /* Early initialization */
     426         760 :     BaseInit();
     427             : 
     428         760 :     InitPostgres(NULL, InvalidOid, NULL, InvalidOid, 0, NULL);
     429             : 
     430         760 :     SetProcessingMode(NormalProcessing);
     431             : 
     432             :     /*
     433             :      * Create a memory context that we will do all our work in.  We do this so
     434             :      * that we can reset the context during error recovery and thereby avoid
     435             :      * possible memory leaks.
     436             :      */
     437         760 :     AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,
     438             :                                           "Autovacuum Launcher",
     439             :                                           ALLOCSET_DEFAULT_SIZES);
     440         760 :     MemoryContextSwitchTo(AutovacMemCxt);
     441             : 
     442             :     /*
     443             :      * If an exception is encountered, processing resumes here.
     444             :      *
     445             :      * This code is a stripped down version of PostgresMain error recovery.
     446             :      *
     447             :      * Note that we use sigsetjmp(..., 1), so that the prevailing signal mask
     448             :      * (to wit, BlockSig) will be restored when longjmp'ing to here.  Thus,
     449             :      * signals other than SIGQUIT will be blocked until we complete error
     450             :      * recovery.  It might seem that this policy makes the HOLD_INTERRUPTS()
     451             :      * call redundant, but it is not since InterruptPending might be set
     452             :      * already.
     453             :      */
     454         760 :     if (sigsetjmp(local_sigjmp_buf, 1) != 0)
     455             :     {
     456             :         /* since not using PG_TRY, must reset error stack by hand */
     457           0 :         error_context_stack = NULL;
     458             : 
     459             :         /* Prevents interrupts while cleaning up */
     460           0 :         HOLD_INTERRUPTS();
     461             : 
     462             :         /* Forget any pending QueryCancel or timeout request */
     463           0 :         disable_all_timeouts(false);
     464           0 :         QueryCancelPending = false; /* second to avoid race condition */
     465             : 
     466             :         /* Report the error to the server log */
     467           0 :         EmitErrorReport();
     468             : 
     469             :         /* Abort the current transaction in order to recover */
     470           0 :         AbortCurrentTransaction();
     471             : 
     472             :         /*
     473             :          * Release any other resources, for the case where we were not in a
     474             :          * transaction.
     475             :          */
     476           0 :         LWLockReleaseAll();
     477           0 :         pgstat_report_wait_end();
     478           0 :         pgaio_error_cleanup();
     479           0 :         UnlockBuffers();
     480             :         /* this is probably dead code, but let's be safe: */
     481           0 :         if (AuxProcessResourceOwner)
     482           0 :             ReleaseAuxProcessResources(false);
     483           0 :         AtEOXact_Buffers(false);
     484           0 :         AtEOXact_SMgr();
     485           0 :         AtEOXact_Files(false);
     486           0 :         AtEOXact_HashTables(false);
     487             : 
     488             :         /*
     489             :          * Now return to normal top-level context and clear ErrorContext for
     490             :          * next time.
     491             :          */
     492           0 :         MemoryContextSwitchTo(AutovacMemCxt);
     493           0 :         FlushErrorState();
     494             : 
     495             :         /* Flush any leaked data in the top-level context */
     496           0 :         MemoryContextReset(AutovacMemCxt);
     497             : 
     498             :         /* don't leave dangling pointers to freed memory */
     499           0 :         DatabaseListCxt = NULL;
     500           0 :         dlist_init(&DatabaseList);
     501             : 
     502             :         /* Now we can allow interrupts again */
     503           0 :         RESUME_INTERRUPTS();
     504             : 
     505             :         /* if in shutdown mode, no need for anything further; just go away */
     506           0 :         if (ShutdownRequestPending)
     507           0 :             AutoVacLauncherShutdown();
     508             : 
     509             :         /*
     510             :          * Sleep at least 1 second after any error.  We don't want to be
     511             :          * filling the error logs as fast as we can.
     512             :          */
     513           0 :         pg_usleep(1000000L);
     514             :     }
     515             : 
     516             :     /* We can now handle ereport(ERROR) */
     517         760 :     PG_exception_stack = &local_sigjmp_buf;
     518             : 
     519             :     /* must unblock signals before calling rebuild_database_list */
     520         760 :     sigprocmask(SIG_SETMASK, &UnBlockSig, NULL);
     521             : 
     522             :     /*
     523             :      * Set always-secure search path.  Launcher doesn't connect to a database,
     524             :      * so this has no effect.
     525             :      */
     526         760 :     SetConfigOption("search_path", "", PGC_SUSET, PGC_S_OVERRIDE);
     527             : 
     528             :     /*
     529             :      * Force zero_damaged_pages OFF in the autovac process, even if it is set
     530             :      * in postgresql.conf.  We don't really want such a dangerous option being
     531             :      * applied non-interactively.
     532             :      */
     533         760 :     SetConfigOption("zero_damaged_pages", "false", PGC_SUSET, PGC_S_OVERRIDE);
     534             : 
     535             :     /*
     536             :      * Force settable timeouts off to avoid letting these settings prevent
     537             :      * regular maintenance from being executed.
     538             :      */
     539         760 :     SetConfigOption("statement_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
     540         760 :     SetConfigOption("transaction_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
     541         760 :     SetConfigOption("lock_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
     542         760 :     SetConfigOption("idle_in_transaction_session_timeout", "0",
     543             :                     PGC_SUSET, PGC_S_OVERRIDE);
     544             : 
     545             :     /*
     546             :      * Force default_transaction_isolation to READ COMMITTED.  We don't want
     547             :      * to pay the overhead of serializable mode, nor add any risk of causing
     548             :      * deadlocks or delaying other transactions.
     549             :      */
     550         760 :     SetConfigOption("default_transaction_isolation", "read committed",
     551             :                     PGC_SUSET, PGC_S_OVERRIDE);
     552             : 
     553             :     /*
     554             :      * Even when system is configured to use a different fetch consistency,
     555             :      * for autovac we always want fresh stats.
     556             :      */
     557         760 :     SetConfigOption("stats_fetch_consistency", "none", PGC_SUSET, PGC_S_OVERRIDE);
     558             : 
     559             :     /*
     560             :      * In emergency mode, just start a worker (unless shutdown was requested)
     561             :      * and go away.
     562             :      */
     563         760 :     if (!AutoVacuumingActive())
     564             :     {
     565           0 :         if (!ShutdownRequestPending)
     566           0 :             do_start_worker();
     567           0 :         proc_exit(0);           /* done */
     568             :     }
     569             : 
     570         760 :     AutoVacuumShmem->av_launcherpid = MyProcPid;
     571             : 
     572             :     /*
     573             :      * Create the initial database list.  The invariant we want this list to
     574             :      * keep is that it's ordered by decreasing next_worker.  As soon as an
     575             :      * entry is updated to a higher time, it will be moved to the front (which
     576             :      * is correct because the only operation is to add autovacuum_naptime to
     577             :      * the entry, and time always increases).
     578             :      */
     579         760 :     rebuild_database_list(InvalidOid);
     580             : 
     581             :     /* loop until shutdown request */
     582       16618 :     while (!ShutdownRequestPending)
     583             :     {
     584             :         struct timeval nap;
     585       16612 :         TimestampTz current_time = 0;
     586             :         bool        can_launch;
     587             : 
     588             :         /*
     589             :          * This loop is a bit different from the normal use of WaitLatch,
     590             :          * because we'd like to sleep before the first launch of a child
     591             :          * process.  So it's WaitLatch, then ResetLatch, then check for
     592             :          * wakening conditions.
     593             :          */
     594             : 
     595       16612 :         launcher_determine_sleep(av_worker_available(), false, &nap);
     596             : 
     597             :         /*
     598             :          * Wait until naptime expires or we get some type of signal (all the
     599             :          * signal handlers will wake us by calling SetLatch).
     600             :          */
     601       16612 :         (void) WaitLatch(MyLatch,
     602             :                          WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
     603       16612 :                          (nap.tv_sec * 1000L) + (nap.tv_usec / 1000L),
     604             :                          WAIT_EVENT_AUTOVACUUM_MAIN);
     605             : 
     606       16606 :         ResetLatch(MyLatch);
     607             : 
     608       16606 :         ProcessAutoVacLauncherInterrupts();
     609             : 
     610             :         /*
     611             :          * a worker finished, or postmaster signaled failure to start a worker
     612             :          */
     613       15858 :         if (got_SIGUSR2)
     614             :         {
     615        9446 :             got_SIGUSR2 = false;
     616             : 
     617             :             /* rebalance cost limits, if needed */
     618        9446 :             if (AutoVacuumShmem->av_signal[AutoVacRebalance])
     619             :             {
     620        4718 :                 LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
     621        4718 :                 AutoVacuumShmem->av_signal[AutoVacRebalance] = false;
     622        4718 :                 autovac_recalculate_workers_for_balance();
     623        4718 :                 LWLockRelease(AutovacuumLock);
     624             :             }
     625             : 
     626        9446 :             if (AutoVacuumShmem->av_signal[AutoVacForkFailed])
     627             :             {
     628             :                 /*
     629             :                  * If the postmaster failed to start a new worker, we sleep
     630             :                  * for a little while and resend the signal.  The new worker's
     631             :                  * state is still in memory, so this is sufficient.  After
     632             :                  * that, we restart the main loop.
     633             :                  *
     634             :                  * XXX should we put a limit to the number of times we retry?
     635             :                  * I don't think it makes much sense, because a future start
     636             :                  * of a worker will continue to fail in the same way.
     637             :                  */
     638           0 :                 AutoVacuumShmem->av_signal[AutoVacForkFailed] = false;
     639           0 :                 pg_usleep(1000000L);    /* 1s */
     640           0 :                 SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER);
     641        4794 :                 continue;
     642             :             }
     643             :         }
     644             : 
     645             :         /*
     646             :          * There are some conditions that we need to check before trying to
     647             :          * start a worker.  First, we need to make sure that there is a worker
     648             :          * slot available.  Second, we need to make sure that no other worker
     649             :          * failed while starting up.
     650             :          */
     651             : 
     652       15858 :         current_time = GetCurrentTimestamp();
     653       15858 :         LWLockAcquire(AutovacuumLock, LW_SHARED);
     654             : 
     655       15858 :         can_launch = av_worker_available();
     656             : 
     657       15858 :         if (AutoVacuumShmem->av_startingWorker != NULL)
     658             :         {
     659             :             int         waittime;
     660          68 :             WorkerInfo  worker = AutoVacuumShmem->av_startingWorker;
     661             : 
     662             :             /*
     663             :              * We can't launch another worker when another one is still
     664             :              * starting up (or failed while doing so), so just sleep for a bit
     665             :              * more; that worker will wake us up again as soon as it's ready.
     666             :              * We will only wait autovacuum_naptime seconds (up to a maximum
     667             :              * of 60 seconds) for this to happen however.  Note that failure
     668             :              * to connect to a particular database is not a problem here,
     669             :              * because the worker removes itself from the startingWorker
     670             :              * pointer before trying to connect.  Problems detected by the
     671             :              * postmaster (like fork() failure) are also reported and handled
     672             :              * differently.  The only problems that may cause this code to
     673             :              * fire are errors in the earlier sections of AutoVacWorkerMain,
     674             :              * before the worker removes the WorkerInfo from the
     675             :              * startingWorker pointer.
     676             :              */
     677          68 :             waittime = Min(autovacuum_naptime, 60) * 1000;
     678          68 :             if (TimestampDifferenceExceeds(worker->wi_launchtime, current_time,
     679             :                                            waittime))
     680             :             {
     681           0 :                 LWLockRelease(AutovacuumLock);
     682           0 :                 LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
     683             : 
     684             :                 /*
     685             :                  * No other process can put a worker in starting mode, so if
     686             :                  * startingWorker is still INVALID after exchanging our lock,
     687             :                  * we assume it's the same one we saw above (so we don't
     688             :                  * recheck the launch time).
     689             :                  */
     690           0 :                 if (AutoVacuumShmem->av_startingWorker != NULL)
     691             :                 {
     692           0 :                     worker = AutoVacuumShmem->av_startingWorker;
     693           0 :                     worker->wi_dboid = InvalidOid;
     694           0 :                     worker->wi_tableoid = InvalidOid;
     695           0 :                     worker->wi_sharedrel = false;
     696           0 :                     worker->wi_proc = NULL;
     697           0 :                     worker->wi_launchtime = 0;
     698           0 :                     dclist_push_head(&AutoVacuumShmem->av_freeWorkers,
     699             :                                      &worker->wi_links);
     700           0 :                     AutoVacuumShmem->av_startingWorker = NULL;
     701           0 :                     ereport(WARNING,
     702             :                             errmsg("autovacuum worker took too long to start; canceled"));
     703             :                 }
     704             :             }
     705             :             else
     706          68 :                 can_launch = false;
     707             :         }
     708       15858 :         LWLockRelease(AutovacuumLock);  /* either shared or exclusive */
     709             : 
     710             :         /* if we can't do anything, just go back to sleep */
     711       15858 :         if (!can_launch)
     712        4794 :             continue;
     713             : 
     714             :         /* We're OK to start a new worker */
     715             : 
     716       11064 :         if (dlist_is_empty(&DatabaseList))
     717             :         {
     718             :             /*
     719             :              * Special case when the list is empty: start a worker right away.
     720             :              * This covers the initial case, when no database is in pgstats
     721             :              * (thus the list is empty).  Note that the constraints in
     722             :              * launcher_determine_sleep keep us from starting workers too
     723             :              * quickly (at most once every autovacuum_naptime when the list is
     724             :              * empty).
     725             :              */
     726          10 :             launch_worker(current_time);
     727             :         }
     728             :         else
     729             :         {
     730             :             /*
     731             :              * because rebuild_database_list constructs a list with most
     732             :              * distant adl_next_worker first, we obtain our database from the
     733             :              * tail of the list.
     734             :              */
     735             :             avl_dbase  *avdb;
     736             : 
     737       11054 :             avdb = dlist_tail_element(avl_dbase, adl_node, &DatabaseList);
     738             : 
     739             :             /*
     740             :              * launch a worker if next_worker is right now or it is in the
     741             :              * past
     742             :              */
     743       11054 :             if (TimestampDifferenceExceeds(avdb->adl_next_worker,
     744             :                                            current_time, 0))
     745        4730 :                 launch_worker(current_time);
     746             :         }
     747             :     }
     748             : 
     749           6 :     AutoVacLauncherShutdown();
     750             : }
     751             : 
     752             : /*
     753             :  * Process any new interrupts.
     754             :  */
     755             : static void
     756       16606 : ProcessAutoVacLauncherInterrupts(void)
     757             : {
     758             :     /* the normal shutdown case */
     759       16606 :     if (ShutdownRequestPending)
     760         748 :         AutoVacLauncherShutdown();
     761             : 
     762       15858 :     if (ConfigReloadPending)
     763             :     {
     764          72 :         int         autovacuum_max_workers_prev = autovacuum_max_workers;
     765             : 
     766          72 :         ConfigReloadPending = false;
     767          72 :         ProcessConfigFile(PGC_SIGHUP);
     768             : 
     769             :         /* shutdown requested in config file? */
     770          72 :         if (!AutoVacuumingActive())
     771           0 :             AutoVacLauncherShutdown();
     772             : 
     773             :         /*
     774             :          * If autovacuum_max_workers changed, emit a WARNING if
     775             :          * autovacuum_worker_slots < autovacuum_max_workers.  If it didn't
     776             :          * change, skip this to avoid too many repeated log messages.
     777             :          */
     778          72 :         if (autovacuum_max_workers_prev != autovacuum_max_workers)
     779           0 :             check_av_worker_gucs();
     780             : 
     781             :         /* rebuild the list in case the naptime changed */
     782          72 :         rebuild_database_list(InvalidOid);
     783             :     }
     784             : 
     785             :     /* Process barrier events */
     786       15858 :     if (ProcSignalBarrierPending)
     787          54 :         ProcessProcSignalBarrier();
     788             : 
     789             :     /* Perform logging of memory contexts of this process */
     790       15858 :     if (LogMemoryContextPending)
     791           0 :         ProcessLogMemoryContextInterrupt();
     792             : 
     793             :     /* Process sinval catchup interrupts that happened while sleeping */
     794       15858 :     ProcessCatchupInterrupt();
     795       15858 : }
     796             : 
     797             : /*
     798             :  * Perform a normal exit from the autovac launcher.
     799             :  */
     800             : static void
     801         754 : AutoVacLauncherShutdown(void)
     802             : {
     803         754 :     ereport(DEBUG1,
     804             :             (errmsg_internal("autovacuum launcher shutting down")));
     805         754 :     AutoVacuumShmem->av_launcherpid = 0;
     806             : 
     807         754 :     proc_exit(0);               /* done */
     808             : }
     809             : 
     810             : /*
     811             :  * Determine the time to sleep, based on the database list.
     812             :  *
     813             :  * The "canlaunch" parameter indicates whether we can start a worker right now,
     814             :  * for example due to the workers being all busy.  If this is false, we will
     815             :  * cause a long sleep, which will be interrupted when a worker exits.
     816             :  */
     817             : static void
     818       16852 : launcher_determine_sleep(bool canlaunch, bool recursing, struct timeval *nap)
     819             : {
     820             :     /*
     821             :      * We sleep until the next scheduled vacuum.  We trust that when the
     822             :      * database list was built, care was taken so that no entries have times
     823             :      * in the past; if the first entry has too close a next_worker value, or a
     824             :      * time in the past, we will sleep a small nominal time.
     825             :      */
     826       16852 :     if (!canlaunch)
     827             :     {
     828        8996 :         nap->tv_sec = autovacuum_naptime;
     829        8996 :         nap->tv_usec = 0;
     830             :     }
     831        7856 :     else if (!dlist_is_empty(&DatabaseList))
     832             :     {
     833        7808 :         TimestampTz current_time = GetCurrentTimestamp();
     834             :         TimestampTz next_wakeup;
     835             :         avl_dbase  *avdb;
     836             :         long        secs;
     837             :         int         usecs;
     838             : 
     839        7808 :         avdb = dlist_tail_element(avl_dbase, adl_node, &DatabaseList);
     840             : 
     841        7808 :         next_wakeup = avdb->adl_next_worker;
     842        7808 :         TimestampDifference(current_time, next_wakeup, &secs, &usecs);
     843             : 
     844        7808 :         nap->tv_sec = secs;
     845        7808 :         nap->tv_usec = usecs;
     846             :     }
     847             :     else
     848             :     {
     849             :         /* list is empty, sleep for whole autovacuum_naptime seconds  */
     850          48 :         nap->tv_sec = autovacuum_naptime;
     851          48 :         nap->tv_usec = 0;
     852             :     }
     853             : 
     854             :     /*
     855             :      * If the result is exactly zero, it means a database had an entry with
     856             :      * time in the past.  Rebuild the list so that the databases are evenly
     857             :      * distributed again, and recalculate the time to sleep.  This can happen
     858             :      * if there are more tables needing vacuum than workers, and they all take
     859             :      * longer to vacuum than autovacuum_naptime.
     860             :      *
     861             :      * We only recurse once.  rebuild_database_list should always return times
     862             :      * in the future, but it seems best not to trust too much on that.
     863             :      */
     864       16852 :     if (nap->tv_sec == 0 && nap->tv_usec == 0 && !recursing)
     865             :     {
     866         240 :         rebuild_database_list(InvalidOid);
     867         240 :         launcher_determine_sleep(canlaunch, true, nap);
     868         240 :         return;
     869             :     }
     870             : 
     871             :     /* The smallest time we'll allow the launcher to sleep. */
     872       16612 :     if (nap->tv_sec <= 0 && nap->tv_usec <= MIN_AUTOVAC_SLEEPTIME * 1000)
     873             :     {
     874        1662 :         nap->tv_sec = 0;
     875        1662 :         nap->tv_usec = MIN_AUTOVAC_SLEEPTIME * 1000;
     876             :     }
     877             : 
     878             :     /*
     879             :      * If the sleep time is too large, clamp it to an arbitrary maximum (plus
     880             :      * any fractional seconds, for simplicity).  This avoids an essentially
     881             :      * infinite sleep in strange cases like the system clock going backwards a
     882             :      * few years.
     883             :      */
     884       16612 :     if (nap->tv_sec > MAX_AUTOVAC_SLEEPTIME)
     885          18 :         nap->tv_sec = MAX_AUTOVAC_SLEEPTIME;
     886             : }
     887             : 
     888             : /*
     889             :  * Build an updated DatabaseList.  It must only contain databases that appear
     890             :  * in pgstats, and must be sorted by next_worker from highest to lowest,
     891             :  * distributed regularly across the next autovacuum_naptime interval.
     892             :  *
     893             :  * Receives the Oid of the database that made this list be generated (we call
     894             :  * this the "new" database, because when the database was already present on
     895             :  * the list, we expect that this function is not called at all).  The
     896             :  * preexisting list, if any, will be used to preserve the order of the
     897             :  * databases in the autovacuum_naptime period.  The new database is put at the
     898             :  * end of the interval.  The actual values are not saved, which should not be
     899             :  * much of a problem.
     900             :  */
     901             : static void
     902        1100 : rebuild_database_list(Oid newdb)
     903             : {
     904             :     List       *dblist;
     905             :     ListCell   *cell;
     906             :     MemoryContext newcxt;
     907             :     MemoryContext oldcxt;
     908             :     MemoryContext tmpcxt;
     909             :     HASHCTL     hctl;
     910             :     int         score;
     911             :     int         nelems;
     912             :     HTAB       *dbhash;
     913             :     dlist_iter  iter;
     914             : 
     915        1100 :     newcxt = AllocSetContextCreate(AutovacMemCxt,
     916             :                                    "Autovacuum database list",
     917             :                                    ALLOCSET_DEFAULT_SIZES);
     918        1100 :     tmpcxt = AllocSetContextCreate(newcxt,
     919             :                                    "Autovacuum database list (tmp)",
     920             :                                    ALLOCSET_DEFAULT_SIZES);
     921        1100 :     oldcxt = MemoryContextSwitchTo(tmpcxt);
     922             : 
     923             :     /*
     924             :      * Implementing this is not as simple as it sounds, because we need to put
     925             :      * the new database at the end of the list; next the databases that were
     926             :      * already on the list, and finally (at the tail of the list) all the
     927             :      * other databases that are not on the existing list.
     928             :      *
     929             :      * To do this, we build an empty hash table of scored databases.  We will
     930             :      * start with the lowest score (zero) for the new database, then
     931             :      * increasing scores for the databases in the existing list, in order, and
     932             :      * lastly increasing scores for all databases gotten via
     933             :      * get_database_list() that are not already on the hash.
     934             :      *
     935             :      * Then we will put all the hash elements into an array, sort the array by
     936             :      * score, and finally put the array elements into the new doubly linked
     937             :      * list.
     938             :      */
     939        1100 :     hctl.keysize = sizeof(Oid);
     940        1100 :     hctl.entrysize = sizeof(avl_dbase);
     941        1100 :     hctl.hcxt = tmpcxt;
     942        1100 :     dbhash = hash_create("autovacuum db hash", 20, &hctl, /* magic number here
     943             :                                                              * FIXME */
     944             :                          HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
     945             : 
     946             :     /* start by inserting the new database */
     947        1100 :     score = 0;
     948        1100 :     if (OidIsValid(newdb))
     949             :     {
     950             :         avl_dbase  *db;
     951             :         PgStat_StatDBEntry *entry;
     952             : 
     953             :         /* only consider this database if it has a pgstat entry */
     954          28 :         entry = pgstat_fetch_stat_dbentry(newdb);
     955          28 :         if (entry != NULL)
     956             :         {
     957             :             /* we assume it isn't found because the hash was just created */
     958          22 :             db = hash_search(dbhash, &newdb, HASH_ENTER, NULL);
     959             : 
     960             :             /* hash_search already filled in the key */
     961          22 :             db->adl_score = score++;
     962             :             /* next_worker is filled in later */
     963             :         }
     964             :     }
     965             : 
     966             :     /* Now insert the databases from the existing list */
     967        1964 :     dlist_foreach(iter, &DatabaseList)
     968             :     {
     969         864 :         avl_dbase  *avdb = dlist_container(avl_dbase, adl_node, iter.cur);
     970             :         avl_dbase  *db;
     971             :         bool        found;
     972             :         PgStat_StatDBEntry *entry;
     973             : 
     974             :         /*
     975             :          * skip databases with no stat entries -- in particular, this gets rid
     976             :          * of dropped databases
     977             :          */
     978         864 :         entry = pgstat_fetch_stat_dbentry(avdb->adl_datid);
     979         864 :         if (entry == NULL)
     980           0 :             continue;
     981             : 
     982         864 :         db = hash_search(dbhash, &(avdb->adl_datid), HASH_ENTER, &found);
     983             : 
     984         864 :         if (!found)
     985             :         {
     986             :             /* hash_search already filled in the key */
     987         864 :             db->adl_score = score++;
     988             :             /* next_worker is filled in later */
     989             :         }
     990             :     }
     991             : 
     992             :     /* finally, insert all qualifying databases not previously inserted */
     993        1100 :     dblist = get_database_list();
     994        4720 :     foreach(cell, dblist)
     995             :     {
     996        3620 :         avw_dbase  *avdb = lfirst(cell);
     997             :         avl_dbase  *db;
     998             :         bool        found;
     999             :         PgStat_StatDBEntry *entry;
    1000             : 
    1001             :         /* only consider databases with a pgstat entry */
    1002        3620 :         entry = pgstat_fetch_stat_dbentry(avdb->adw_datid);
    1003        3620 :         if (entry == NULL)
    1004        1650 :             continue;
    1005             : 
    1006        1970 :         db = hash_search(dbhash, &(avdb->adw_datid), HASH_ENTER, &found);
    1007             :         /* only update the score if the database was not already on the hash */
    1008        1970 :         if (!found)
    1009             :         {
    1010             :             /* hash_search already filled in the key */
    1011        1084 :             db->adl_score = score++;
    1012             :             /* next_worker is filled in later */
    1013             :         }
    1014             :     }
    1015        1100 :     nelems = score;
    1016             : 
    1017             :     /* from here on, the allocated memory belongs to the new list */
    1018        1100 :     MemoryContextSwitchTo(newcxt);
    1019        1100 :     dlist_init(&DatabaseList);
    1020             : 
    1021        1100 :     if (nelems > 0)
    1022             :     {
    1023             :         TimestampTz current_time;
    1024             :         int         millis_increment;
    1025             :         avl_dbase  *dbary;
    1026             :         avl_dbase  *db;
    1027             :         HASH_SEQ_STATUS seq;
    1028             :         int         i;
    1029             : 
    1030             :         /* put all the hash elements into an array */
    1031        1062 :         dbary = palloc(nelems * sizeof(avl_dbase));
    1032             :         /* keep Valgrind quiet */
    1033             : #ifdef USE_VALGRIND
    1034             :         avl_dbase_array = dbary;
    1035             : #endif
    1036             : 
    1037        1062 :         i = 0;
    1038        1062 :         hash_seq_init(&seq, dbhash);
    1039        3032 :         while ((db = hash_seq_search(&seq)) != NULL)
    1040        1970 :             memcpy(&(dbary[i++]), db, sizeof(avl_dbase));
    1041             : 
    1042             :         /* sort the array */
    1043        1062 :         qsort(dbary, nelems, sizeof(avl_dbase), db_comparator);
    1044             : 
    1045             :         /*
    1046             :          * Determine the time interval between databases in the schedule. If
    1047             :          * we see that the configured naptime would take us to sleep times
    1048             :          * lower than our min sleep time (which launcher_determine_sleep is
    1049             :          * coded not to allow), silently use a larger naptime (but don't touch
    1050             :          * the GUC variable).
    1051             :          */
    1052        1062 :         millis_increment = 1000.0 * autovacuum_naptime / nelems;
    1053        1062 :         if (millis_increment <= MIN_AUTOVAC_SLEEPTIME)
    1054           0 :             millis_increment = MIN_AUTOVAC_SLEEPTIME * 1.1;
    1055             : 
    1056        1062 :         current_time = GetCurrentTimestamp();
    1057             : 
    1058             :         /*
    1059             :          * move the elements from the array into the dlist, setting the
    1060             :          * next_worker while walking the array
    1061             :          */
    1062        3032 :         for (i = 0; i < nelems; i++)
    1063             :         {
    1064        1970 :             db = &(dbary[i]);
    1065             : 
    1066        1970 :             current_time = TimestampTzPlusMilliseconds(current_time,
    1067             :                                                        millis_increment);
    1068        1970 :             db->adl_next_worker = current_time;
    1069             : 
    1070             :             /* later elements should go closer to the head of the list */
    1071        1970 :             dlist_push_head(&DatabaseList, &db->adl_node);
    1072             :         }
    1073             :     }
    1074             : 
    1075             :     /* all done, clean up memory */
    1076        1100 :     if (DatabaseListCxt != NULL)
    1077         340 :         MemoryContextDelete(DatabaseListCxt);
    1078        1100 :     MemoryContextDelete(tmpcxt);
    1079        1100 :     DatabaseListCxt = newcxt;
    1080        1100 :     MemoryContextSwitchTo(oldcxt);
    1081        1100 : }
    1082             : 
    1083             : /* qsort comparator for avl_dbase, using adl_score */
    1084             : static int
    1085        1310 : db_comparator(const void *a, const void *b)
    1086             : {
    1087        2620 :     return pg_cmp_s32(((const avl_dbase *) a)->adl_score,
    1088        1310 :                       ((const avl_dbase *) b)->adl_score);
    1089             : }
    1090             : 
    1091             : /*
    1092             :  * do_start_worker
    1093             :  *
    1094             :  * Bare-bones procedure for starting an autovacuum worker from the launcher.
    1095             :  * It determines what database to work on, sets up shared memory stuff and
    1096             :  * signals postmaster to start the worker.  It fails gracefully if invoked when
    1097             :  * autovacuum_workers are already active.
    1098             :  *
    1099             :  * Return value is the OID of the database that the worker is going to process,
    1100             :  * or InvalidOid if no worker was actually started.
    1101             :  */
    1102             : static Oid
    1103        4740 : do_start_worker(void)
    1104             : {
    1105             :     List       *dblist;
    1106             :     ListCell   *cell;
    1107             :     TransactionId xidForceLimit;
    1108             :     MultiXactId multiForceLimit;
    1109             :     bool        for_xid_wrap;
    1110             :     bool        for_multi_wrap;
    1111             :     avw_dbase  *avdb;
    1112             :     TimestampTz current_time;
    1113        4740 :     bool        skipit = false;
    1114        4740 :     Oid         retval = InvalidOid;
    1115             :     MemoryContext tmpcxt,
    1116             :                 oldcxt;
    1117             : 
    1118             :     /* return quickly when there are no free workers */
    1119        4740 :     LWLockAcquire(AutovacuumLock, LW_SHARED);
    1120        4740 :     if (!av_worker_available())
    1121             :     {
    1122           0 :         LWLockRelease(AutovacuumLock);
    1123           0 :         return InvalidOid;
    1124             :     }
    1125        4740 :     LWLockRelease(AutovacuumLock);
    1126             : 
    1127             :     /*
    1128             :      * Create and switch to a temporary context to avoid leaking the memory
    1129             :      * allocated for the database list.
    1130             :      */
    1131        4740 :     tmpcxt = AllocSetContextCreate(CurrentMemoryContext,
    1132             :                                    "Autovacuum start worker (tmp)",
    1133             :                                    ALLOCSET_DEFAULT_SIZES);
    1134        4740 :     oldcxt = MemoryContextSwitchTo(tmpcxt);
    1135             : 
    1136             :     /* Get a list of databases */
    1137        4740 :     dblist = get_database_list();
    1138             : 
    1139             :     /*
    1140             :      * Determine the oldest datfrozenxid/relfrozenxid that we will allow to
    1141             :      * pass without forcing a vacuum.  (This limit can be tightened for
    1142             :      * particular tables, but not loosened.)
    1143             :      */
    1144        4740 :     recentXid = ReadNextTransactionId();
    1145        4740 :     xidForceLimit = recentXid - autovacuum_freeze_max_age;
    1146             :     /* ensure it's a "normal" XID, else TransactionIdPrecedes misbehaves */
    1147             :     /* this can cause the limit to go backwards by 3, but that's OK */
    1148        4740 :     if (xidForceLimit < FirstNormalTransactionId)
    1149           0 :         xidForceLimit -= FirstNormalTransactionId;
    1150             : 
    1151             :     /* Also determine the oldest datminmxid we will consider. */
    1152        4740 :     recentMulti = ReadNextMultiXactId();
    1153        4740 :     multiForceLimit = recentMulti - MultiXactMemberFreezeThreshold();
    1154        4740 :     if (multiForceLimit < FirstMultiXactId)
    1155           0 :         multiForceLimit -= FirstMultiXactId;
    1156             : 
    1157             :     /*
    1158             :      * Choose a database to connect to.  We pick the database that was least
    1159             :      * recently auto-vacuumed, or one that needs vacuuming to prevent Xid
    1160             :      * wraparound-related data loss.  If any db at risk of Xid wraparound is
    1161             :      * found, we pick the one with oldest datfrozenxid, independently of
    1162             :      * autovacuum times; similarly we pick the one with the oldest datminmxid
    1163             :      * if any is in MultiXactId wraparound.  Note that those in Xid wraparound
    1164             :      * danger are given more priority than those in multi wraparound danger.
    1165             :      *
    1166             :      * Note that a database with no stats entry is not considered, except for
    1167             :      * Xid wraparound purposes.  The theory is that if no one has ever
    1168             :      * connected to it since the stats were last initialized, it doesn't need
    1169             :      * vacuuming.
    1170             :      *
    1171             :      * XXX This could be improved if we had more info about whether it needs
    1172             :      * vacuuming before connecting to it.  Perhaps look through the pgstats
    1173             :      * data for the database's tables?  One idea is to keep track of the
    1174             :      * number of new and dead tuples per database in pgstats.  However it
    1175             :      * isn't clear how to construct a metric that measures that and not cause
    1176             :      * starvation for less busy databases.
    1177             :      */
    1178        4740 :     avdb = NULL;
    1179        4740 :     for_xid_wrap = false;
    1180        4740 :     for_multi_wrap = false;
    1181        4740 :     current_time = GetCurrentTimestamp();
    1182       19128 :     foreach(cell, dblist)
    1183             :     {
    1184       14388 :         avw_dbase  *tmp = lfirst(cell);
    1185             :         dlist_iter  iter;
    1186             : 
    1187             :         /* Check to see if this one is at risk of wraparound */
    1188       14388 :         if (TransactionIdPrecedes(tmp->adw_frozenxid, xidForceLimit))
    1189             :         {
    1190       11434 :             if (avdb == NULL ||
    1191        4548 :                 TransactionIdPrecedes(tmp->adw_frozenxid,
    1192             :                                       avdb->adw_frozenxid))
    1193        2502 :                 avdb = tmp;
    1194        6886 :             for_xid_wrap = true;
    1195       11678 :             continue;
    1196             :         }
    1197        7502 :         else if (for_xid_wrap)
    1198         120 :             continue;           /* ignore not-at-risk DBs */
    1199        7382 :         else if (MultiXactIdPrecedes(tmp->adw_minmulti, multiForceLimit))
    1200             :         {
    1201           0 :             if (avdb == NULL ||
    1202           0 :                 MultiXactIdPrecedes(tmp->adw_minmulti, avdb->adw_minmulti))
    1203           0 :                 avdb = tmp;
    1204           0 :             for_multi_wrap = true;
    1205           0 :             continue;
    1206             :         }
    1207        7382 :         else if (for_multi_wrap)
    1208           0 :             continue;           /* ignore not-at-risk DBs */
    1209             : 
    1210             :         /* Find pgstat entry if any */
    1211        7382 :         tmp->adw_entry = pgstat_fetch_stat_dbentry(tmp->adw_datid);
    1212             : 
    1213             :         /*
    1214             :          * Skip a database with no pgstat entry; it means it hasn't seen any
    1215             :          * activity.
    1216             :          */
    1217        7382 :         if (!tmp->adw_entry)
    1218         180 :             continue;
    1219             : 
    1220             :         /*
    1221             :          * Also, skip a database that appears on the database list as having
    1222             :          * been processed recently (less than autovacuum_naptime seconds ago).
    1223             :          * We do this so that we don't select a database which we just
    1224             :          * selected, but that pgstat hasn't gotten around to updating the last
    1225             :          * autovacuum time yet.
    1226             :          */
    1227        7202 :         skipit = false;
    1228             : 
    1229       14620 :         dlist_reverse_foreach(iter, &DatabaseList)
    1230             :         {
    1231       14574 :             avl_dbase  *dbp = dlist_container(avl_dbase, adl_node, iter.cur);
    1232             : 
    1233       14574 :             if (dbp->adl_datid == tmp->adw_datid)
    1234             :             {
    1235             :                 /*
    1236             :                  * Skip this database if its next_worker value falls between
    1237             :                  * the current time and the current time plus naptime.
    1238             :                  */
    1239        7156 :                 if (!TimestampDifferenceExceeds(dbp->adl_next_worker,
    1240        4492 :                                                 current_time, 0) &&
    1241        4492 :                     !TimestampDifferenceExceeds(current_time,
    1242             :                                                 dbp->adl_next_worker,
    1243             :                                                 autovacuum_naptime * 1000))
    1244        4492 :                     skipit = true;
    1245             : 
    1246        7156 :                 break;
    1247             :             }
    1248             :         }
    1249        7202 :         if (skipit)
    1250        4492 :             continue;
    1251             : 
    1252             :         /*
    1253             :          * Remember the db with oldest autovac time.  (If we are here, both
    1254             :          * tmp->entry and db->entry must be non-null.)
    1255             :          */
    1256        2710 :         if (avdb == NULL ||
    1257         318 :             tmp->adw_entry->last_autovac_time < avdb->adw_entry->last_autovac_time)
    1258        2506 :             avdb = tmp;
    1259             :     }
    1260             : 
    1261             :     /* Found a database -- process it */
    1262        4740 :     if (avdb != NULL)
    1263             :     {
    1264             :         WorkerInfo  worker;
    1265             :         dlist_node *wptr;
    1266             : 
    1267        4730 :         LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    1268             : 
    1269             :         /*
    1270             :          * Get a worker entry from the freelist.  We checked above, so there
    1271             :          * really should be a free slot.
    1272             :          */
    1273        4730 :         wptr = dclist_pop_head_node(&AutoVacuumShmem->av_freeWorkers);
    1274             : 
    1275        4730 :         worker = dlist_container(WorkerInfoData, wi_links, wptr);
    1276        4730 :         worker->wi_dboid = avdb->adw_datid;
    1277        4730 :         worker->wi_proc = NULL;
    1278        4730 :         worker->wi_launchtime = GetCurrentTimestamp();
    1279             : 
    1280        4730 :         AutoVacuumShmem->av_startingWorker = worker;
    1281             : 
    1282        4730 :         LWLockRelease(AutovacuumLock);
    1283             : 
    1284        4730 :         SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER);
    1285             : 
    1286        4730 :         retval = avdb->adw_datid;
    1287             :     }
    1288          10 :     else if (skipit)
    1289             :     {
    1290             :         /*
    1291             :          * If we skipped all databases on the list, rebuild it, because it
    1292             :          * probably contains a dropped database.
    1293             :          */
    1294           0 :         rebuild_database_list(InvalidOid);
    1295             :     }
    1296             : 
    1297        4740 :     MemoryContextSwitchTo(oldcxt);
    1298        4740 :     MemoryContextDelete(tmpcxt);
    1299             : 
    1300        4740 :     return retval;
    1301             : }
    1302             : 
    1303             : /*
    1304             :  * launch_worker
    1305             :  *
    1306             :  * Wrapper for starting a worker from the launcher.  Besides actually starting
    1307             :  * it, update the database list to reflect the next time that another one will
    1308             :  * need to be started on the selected database.  The actual database choice is
    1309             :  * left to do_start_worker.
    1310             :  *
    1311             :  * This routine is also expected to insert an entry into the database list if
    1312             :  * the selected database was previously absent from the list.
    1313             :  */
    1314             : static void
    1315        4740 : launch_worker(TimestampTz now)
    1316             : {
    1317             :     Oid         dbid;
    1318             :     dlist_iter  iter;
    1319             : 
    1320        4740 :     dbid = do_start_worker();
    1321        4740 :     if (OidIsValid(dbid))
    1322             :     {
    1323        4730 :         bool        found = false;
    1324             : 
    1325             :         /*
    1326             :          * Walk the database list and update the corresponding entry.  If the
    1327             :          * database is not on the list, we'll recreate the list.
    1328             :          */
    1329       10188 :         dlist_foreach(iter, &DatabaseList)
    1330             :         {
    1331       10160 :             avl_dbase  *avdb = dlist_container(avl_dbase, adl_node, iter.cur);
    1332             : 
    1333       10160 :             if (avdb->adl_datid == dbid)
    1334             :             {
    1335        4702 :                 found = true;
    1336             : 
    1337             :                 /*
    1338             :                  * add autovacuum_naptime seconds to the current time, and use
    1339             :                  * that as the new "next_worker" field for this database.
    1340             :                  */
    1341        4702 :                 avdb->adl_next_worker =
    1342        4702 :                     TimestampTzPlusMilliseconds(now, autovacuum_naptime * 1000);
    1343             : 
    1344        4702 :                 dlist_move_head(&DatabaseList, iter.cur);
    1345        4702 :                 break;
    1346             :             }
    1347             :         }
    1348             : 
    1349             :         /*
    1350             :          * If the database was not present in the database list, we rebuild
    1351             :          * the list.  It's possible that the database does not get into the
    1352             :          * list anyway, for example if it's a database that doesn't have a
    1353             :          * pgstat entry, but this is not a problem because we don't want to
    1354             :          * schedule workers regularly into those in any case.
    1355             :          */
    1356        4730 :         if (!found)
    1357          28 :             rebuild_database_list(dbid);
    1358             :     }
    1359        4740 : }
    1360             : 
    1361             : /*
    1362             :  * Called from postmaster to signal a failure to fork a process to become
    1363             :  * worker.  The postmaster should kill(SIGUSR2) the launcher shortly
    1364             :  * after calling this function.
    1365             :  */
    1366             : void
    1367           0 : AutoVacWorkerFailed(void)
    1368             : {
    1369           0 :     AutoVacuumShmem->av_signal[AutoVacForkFailed] = true;
    1370           0 : }
    1371             : 
    1372             : /* SIGUSR2: a worker is up and running, or just finished, or failed to fork */
    1373             : static void
    1374        9446 : avl_sigusr2_handler(SIGNAL_ARGS)
    1375             : {
    1376        9446 :     got_SIGUSR2 = true;
    1377        9446 :     SetLatch(MyLatch);
    1378        9446 : }
    1379             : 
    1380             : 
    1381             : /********************************************************************
    1382             :  *                    AUTOVACUUM WORKER CODE
    1383             :  ********************************************************************/
    1384             : 
    1385             : /*
    1386             :  * Main entry point for autovacuum worker processes.
    1387             :  */
    1388             : void
    1389        4732 : AutoVacWorkerMain(const void *startup_data, size_t startup_data_len)
    1390             : {
    1391             :     sigjmp_buf  local_sigjmp_buf;
    1392             :     Oid         dbid;
    1393             : 
    1394             :     Assert(startup_data_len == 0);
    1395             : 
    1396             :     /* Release postmaster's working memory context */
    1397        4732 :     if (PostmasterContext)
    1398             :     {
    1399        4732 :         MemoryContextDelete(PostmasterContext);
    1400        4732 :         PostmasterContext = NULL;
    1401             :     }
    1402             : 
    1403        4732 :     MyBackendType = B_AUTOVAC_WORKER;
    1404        4732 :     init_ps_display(NULL);
    1405             : 
    1406             :     Assert(GetProcessingMode() == InitProcessing);
    1407             : 
    1408             :     /*
    1409             :      * Set up signal handlers.  We operate on databases much like a regular
    1410             :      * backend, so we use the same signal handling.  See equivalent code in
    1411             :      * tcop/postgres.c.
    1412             :      */
    1413        4732 :     pqsignal(SIGHUP, SignalHandlerForConfigReload);
    1414             : 
    1415             :     /*
    1416             :      * SIGINT is used to signal canceling the current table's vacuum; SIGTERM
    1417             :      * means abort and exit cleanly, and SIGQUIT means abandon ship.
    1418             :      */
    1419        4732 :     pqsignal(SIGINT, StatementCancelHandler);
    1420        4732 :     pqsignal(SIGTERM, die);
    1421             :     /* SIGQUIT handler was already set up by InitPostmasterChild */
    1422             : 
    1423        4732 :     InitializeTimeouts();       /* establishes SIGALRM handler */
    1424             : 
    1425        4732 :     pqsignal(SIGPIPE, SIG_IGN);
    1426        4732 :     pqsignal(SIGUSR1, procsignal_sigusr1_handler);
    1427        4732 :     pqsignal(SIGUSR2, SIG_IGN);
    1428        4732 :     pqsignal(SIGFPE, FloatExceptionHandler);
    1429        4732 :     pqsignal(SIGCHLD, SIG_DFL);
    1430             : 
    1431             :     /*
    1432             :      * Create a per-backend PGPROC struct in shared memory.  We must do this
    1433             :      * before we can use LWLocks or access any shared memory.
    1434             :      */
    1435        4732 :     InitProcess();
    1436             : 
    1437             :     /* Early initialization */
    1438        4732 :     BaseInit();
    1439             : 
    1440             :     /*
    1441             :      * If an exception is encountered, processing resumes here.
    1442             :      *
    1443             :      * Unlike most auxiliary processes, we don't attempt to continue
    1444             :      * processing after an error; we just clean up and exit.  The autovac
    1445             :      * launcher is responsible for spawning another worker later.
    1446             :      *
    1447             :      * Note that we use sigsetjmp(..., 1), so that the prevailing signal mask
    1448             :      * (to wit, BlockSig) will be restored when longjmp'ing to here.  Thus,
    1449             :      * signals other than SIGQUIT will be blocked until we exit.  It might
    1450             :      * seem that this policy makes the HOLD_INTERRUPTS() call redundant, but
    1451             :      * it is not since InterruptPending might be set already.
    1452             :      */
    1453        4732 :     if (sigsetjmp(local_sigjmp_buf, 1) != 0)
    1454             :     {
    1455             :         /* since not using PG_TRY, must reset error stack by hand */
    1456           0 :         error_context_stack = NULL;
    1457             : 
    1458             :         /* Prevents interrupts while cleaning up */
    1459           0 :         HOLD_INTERRUPTS();
    1460             : 
    1461             :         /* Report the error to the server log */
    1462           0 :         EmitErrorReport();
    1463             : 
    1464             :         /*
    1465             :          * We can now go away.  Note that because we called InitProcess, a
    1466             :          * callback was registered to do ProcKill, which will clean up
    1467             :          * necessary state.
    1468             :          */
    1469           0 :         proc_exit(0);
    1470             :     }
    1471             : 
    1472             :     /* We can now handle ereport(ERROR) */
    1473        4732 :     PG_exception_stack = &local_sigjmp_buf;
    1474             : 
    1475        4732 :     sigprocmask(SIG_SETMASK, &UnBlockSig, NULL);
    1476             : 
    1477             :     /*
    1478             :      * Set always-secure search path, so malicious users can't redirect user
    1479             :      * code (e.g. pg_index.indexprs).  (That code runs in a
    1480             :      * SECURITY_RESTRICTED_OPERATION sandbox, so malicious users could not
    1481             :      * take control of the entire autovacuum worker in any case.)
    1482             :      */
    1483        4732 :     SetConfigOption("search_path", "", PGC_SUSET, PGC_S_OVERRIDE);
    1484             : 
    1485             :     /*
    1486             :      * Force zero_damaged_pages OFF in the autovac process, even if it is set
    1487             :      * in postgresql.conf.  We don't really want such a dangerous option being
    1488             :      * applied non-interactively.
    1489             :      */
    1490        4732 :     SetConfigOption("zero_damaged_pages", "false", PGC_SUSET, PGC_S_OVERRIDE);
    1491             : 
    1492             :     /*
    1493             :      * Force settable timeouts off to avoid letting these settings prevent
    1494             :      * regular maintenance from being executed.
    1495             :      */
    1496        4732 :     SetConfigOption("statement_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
    1497        4732 :     SetConfigOption("transaction_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
    1498        4732 :     SetConfigOption("lock_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
    1499        4732 :     SetConfigOption("idle_in_transaction_session_timeout", "0",
    1500             :                     PGC_SUSET, PGC_S_OVERRIDE);
    1501             : 
    1502             :     /*
    1503             :      * Force default_transaction_isolation to READ COMMITTED.  We don't want
    1504             :      * to pay the overhead of serializable mode, nor add any risk of causing
    1505             :      * deadlocks or delaying other transactions.
    1506             :      */
    1507        4732 :     SetConfigOption("default_transaction_isolation", "read committed",
    1508             :                     PGC_SUSET, PGC_S_OVERRIDE);
    1509             : 
    1510             :     /*
    1511             :      * Force synchronous replication off to allow regular maintenance even if
    1512             :      * we are waiting for standbys to connect. This is important to ensure we
    1513             :      * aren't blocked from performing anti-wraparound tasks.
    1514             :      */
    1515        4732 :     if (synchronous_commit > SYNCHRONOUS_COMMIT_LOCAL_FLUSH)
    1516        4732 :         SetConfigOption("synchronous_commit", "local",
    1517             :                         PGC_SUSET, PGC_S_OVERRIDE);
    1518             : 
    1519             :     /*
    1520             :      * Even when system is configured to use a different fetch consistency,
    1521             :      * for autovac we always want fresh stats.
    1522             :      */
    1523        4732 :     SetConfigOption("stats_fetch_consistency", "none", PGC_SUSET, PGC_S_OVERRIDE);
    1524             : 
    1525             :     /*
    1526             :      * Get the info about the database we're going to work on.
    1527             :      */
    1528        4732 :     LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    1529             : 
    1530             :     /*
    1531             :      * beware of startingWorker being INVALID; this should normally not
    1532             :      * happen, but if a worker fails after forking and before this, the
    1533             :      * launcher might have decided to remove it from the queue and start
    1534             :      * again.
    1535             :      */
    1536        4732 :     if (AutoVacuumShmem->av_startingWorker != NULL)
    1537             :     {
    1538        4732 :         MyWorkerInfo = AutoVacuumShmem->av_startingWorker;
    1539        4732 :         dbid = MyWorkerInfo->wi_dboid;
    1540        4732 :         MyWorkerInfo->wi_proc = MyProc;
    1541             : 
    1542             :         /* insert into the running list */
    1543        4732 :         dlist_push_head(&AutoVacuumShmem->av_runningWorkers,
    1544        4732 :                         &MyWorkerInfo->wi_links);
    1545             : 
    1546             :         /*
    1547             :          * remove from the "starting" pointer, so that the launcher can start
    1548             :          * a new worker if required
    1549             :          */
    1550        4732 :         AutoVacuumShmem->av_startingWorker = NULL;
    1551        4732 :         LWLockRelease(AutovacuumLock);
    1552             : 
    1553        4732 :         on_shmem_exit(FreeWorkerInfo, 0);
    1554             : 
    1555             :         /* wake up the launcher */
    1556        4732 :         if (AutoVacuumShmem->av_launcherpid != 0)
    1557        4732 :             kill(AutoVacuumShmem->av_launcherpid, SIGUSR2);
    1558             :     }
    1559             :     else
    1560             :     {
    1561             :         /* no worker entry for me, go away */
    1562           0 :         elog(WARNING, "autovacuum worker started without a worker entry");
    1563           0 :         dbid = InvalidOid;
    1564           0 :         LWLockRelease(AutovacuumLock);
    1565             :     }
    1566             : 
    1567        4732 :     if (OidIsValid(dbid))
    1568             :     {
    1569             :         char        dbname[NAMEDATALEN];
    1570             : 
    1571             :         /*
    1572             :          * Report autovac startup to the cumulative stats system.  We
    1573             :          * deliberately do this before InitPostgres, so that the
    1574             :          * last_autovac_time will get updated even if the connection attempt
    1575             :          * fails.  This is to prevent autovac from getting "stuck" repeatedly
    1576             :          * selecting an unopenable database, rather than making any progress
    1577             :          * on stuff it can connect to.
    1578             :          */
    1579        4732 :         pgstat_report_autovac(dbid);
    1580             : 
    1581             :         /*
    1582             :          * Connect to the selected database, specifying no particular user,
    1583             :          * and ignoring datallowconn.  Collect the database's name for
    1584             :          * display.
    1585             :          *
    1586             :          * Note: if we have selected a just-deleted database (due to using
    1587             :          * stale stats info), we'll fail and exit here.
    1588             :          */
    1589        4732 :         InitPostgres(NULL, dbid, NULL, InvalidOid,
    1590             :                      INIT_PG_OVERRIDE_ALLOW_CONNS,
    1591             :                      dbname);
    1592        4732 :         SetProcessingMode(NormalProcessing);
    1593        4732 :         set_ps_display(dbname);
    1594        4732 :         ereport(DEBUG1,
    1595             :                 (errmsg_internal("autovacuum: processing database \"%s\"", dbname)));
    1596             : 
    1597        4732 :         if (PostAuthDelay)
    1598           0 :             pg_usleep(PostAuthDelay * 1000000L);
    1599             : 
    1600             :         /* And do an appropriate amount of work */
    1601        4732 :         recentXid = ReadNextTransactionId();
    1602        4732 :         recentMulti = ReadNextMultiXactId();
    1603        4732 :         do_autovacuum();
    1604             :     }
    1605             : 
    1606             :     /*
    1607             :      * The launcher will be notified of my death in ProcKill, *if* we managed
    1608             :      * to get a worker slot at all
    1609             :      */
    1610             : 
    1611             :     /* All done, go away */
    1612        4730 :     proc_exit(0);
    1613             : }
    1614             : 
    1615             : /*
    1616             :  * Return a WorkerInfo to the free list
    1617             :  */
    1618             : static void
    1619        4732 : FreeWorkerInfo(int code, Datum arg)
    1620             : {
    1621        4732 :     if (MyWorkerInfo != NULL)
    1622             :     {
    1623        4732 :         LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    1624             : 
    1625             :         /*
    1626             :          * Wake the launcher up so that he can launch a new worker immediately
    1627             :          * if required.  We only save the launcher's PID in local memory here;
    1628             :          * the actual signal will be sent when the PGPROC is recycled.  Note
    1629             :          * that we always do this, so that the launcher can rebalance the cost
    1630             :          * limit setting of the remaining workers.
    1631             :          *
    1632             :          * We somewhat ignore the risk that the launcher changes its PID
    1633             :          * between us reading it and the actual kill; we expect ProcKill to be
    1634             :          * called shortly after us, and we assume that PIDs are not reused too
    1635             :          * quickly after a process exits.
    1636             :          */
    1637        4732 :         AutovacuumLauncherPid = AutoVacuumShmem->av_launcherpid;
    1638             : 
    1639        4732 :         dlist_delete(&MyWorkerInfo->wi_links);
    1640        4732 :         MyWorkerInfo->wi_dboid = InvalidOid;
    1641        4732 :         MyWorkerInfo->wi_tableoid = InvalidOid;
    1642        4732 :         MyWorkerInfo->wi_sharedrel = false;
    1643        4732 :         MyWorkerInfo->wi_proc = NULL;
    1644        4732 :         MyWorkerInfo->wi_launchtime = 0;
    1645        4732 :         pg_atomic_clear_flag(&MyWorkerInfo->wi_dobalance);
    1646        4732 :         dclist_push_head(&AutoVacuumShmem->av_freeWorkers,
    1647        4732 :                          &MyWorkerInfo->wi_links);
    1648             :         /* not mine anymore */
    1649        4732 :         MyWorkerInfo = NULL;
    1650             : 
    1651             :         /*
    1652             :          * now that we're inactive, cause a rebalancing of the surviving
    1653             :          * workers
    1654             :          */
    1655        4732 :         AutoVacuumShmem->av_signal[AutoVacRebalance] = true;
    1656        4732 :         LWLockRelease(AutovacuumLock);
    1657             :     }
    1658        4732 : }
    1659             : 
    1660             : /*
    1661             :  * Update vacuum cost-based delay-related parameters for autovacuum workers and
    1662             :  * backends executing VACUUM or ANALYZE using the value of relevant GUCs and
    1663             :  * global state. This must be called during setup for vacuum and after every
    1664             :  * config reload to ensure up-to-date values.
    1665             :  */
    1666             : void
    1667      537944 : VacuumUpdateCosts(void)
    1668             : {
    1669      537944 :     if (MyWorkerInfo)
    1670             :     {
    1671      524280 :         if (av_storage_param_cost_delay >= 0)
    1672           0 :             vacuum_cost_delay = av_storage_param_cost_delay;
    1673      524280 :         else if (autovacuum_vac_cost_delay >= 0)
    1674      524280 :             vacuum_cost_delay = autovacuum_vac_cost_delay;
    1675             :         else
    1676             :             /* fall back to VacuumCostDelay */
    1677           0 :             vacuum_cost_delay = VacuumCostDelay;
    1678             : 
    1679      524280 :         AutoVacuumUpdateCostLimit();
    1680             :     }
    1681             :     else
    1682             :     {
    1683             :         /* Must be explicit VACUUM or ANALYZE */
    1684       13664 :         vacuum_cost_delay = VacuumCostDelay;
    1685       13664 :         vacuum_cost_limit = VacuumCostLimit;
    1686             :     }
    1687             : 
    1688             :     /*
    1689             :      * If configuration changes are allowed to impact VacuumCostActive, make
    1690             :      * sure it is updated.
    1691             :      */
    1692      537944 :     if (VacuumFailsafeActive)
    1693             :         Assert(!VacuumCostActive);
    1694      537944 :     else if (vacuum_cost_delay > 0)
    1695      524280 :         VacuumCostActive = true;
    1696             :     else
    1697             :     {
    1698       13664 :         VacuumCostActive = false;
    1699       13664 :         VacuumCostBalance = 0;
    1700             :     }
    1701             : 
    1702             :     /*
    1703             :      * Since the cost logging requires a lock, avoid rendering the log message
    1704             :      * in case we are using a message level where the log wouldn't be emitted.
    1705             :      */
    1706      537944 :     if (MyWorkerInfo && message_level_is_interesting(DEBUG2))
    1707             :     {
    1708             :         Oid         dboid,
    1709             :                     tableoid;
    1710             : 
    1711             :         Assert(!LWLockHeldByMe(AutovacuumLock));
    1712             : 
    1713           0 :         LWLockAcquire(AutovacuumLock, LW_SHARED);
    1714           0 :         dboid = MyWorkerInfo->wi_dboid;
    1715           0 :         tableoid = MyWorkerInfo->wi_tableoid;
    1716           0 :         LWLockRelease(AutovacuumLock);
    1717             : 
    1718           0 :         elog(DEBUG2,
    1719             :              "Autovacuum VacuumUpdateCosts(db=%u, rel=%u, dobalance=%s, cost_limit=%d, cost_delay=%g active=%s failsafe=%s)",
    1720             :              dboid, tableoid, pg_atomic_unlocked_test_flag(&MyWorkerInfo->wi_dobalance) ? "no" : "yes",
    1721             :              vacuum_cost_limit, vacuum_cost_delay,
    1722             :              vacuum_cost_delay > 0 ? "yes" : "no",
    1723             :              VacuumFailsafeActive ? "yes" : "no");
    1724             :     }
    1725      537944 : }
    1726             : 
    1727             : /*
    1728             :  * Update vacuum_cost_limit with the correct value for an autovacuum worker,
    1729             :  * given the value of other relevant cost limit parameters and the number of
    1730             :  * workers across which the limit must be balanced. Autovacuum workers must
    1731             :  * call this regularly in case av_nworkersForBalance has been updated by
    1732             :  * another worker or by the autovacuum launcher. They must also call it after a
    1733             :  * config reload.
    1734             :  */
    1735             : void
    1736      535824 : AutoVacuumUpdateCostLimit(void)
    1737             : {
    1738      535824 :     if (!MyWorkerInfo)
    1739           0 :         return;
    1740             : 
    1741             :     /*
    1742             :      * note: in cost_limit, zero also means use value from elsewhere, because
    1743             :      * zero is not a valid value.
    1744             :      */
    1745             : 
    1746      535824 :     if (av_storage_param_cost_limit > 0)
    1747           0 :         vacuum_cost_limit = av_storage_param_cost_limit;
    1748             :     else
    1749             :     {
    1750             :         int         nworkers_for_balance;
    1751             : 
    1752      535824 :         if (autovacuum_vac_cost_limit > 0)
    1753           0 :             vacuum_cost_limit = autovacuum_vac_cost_limit;
    1754             :         else
    1755      535824 :             vacuum_cost_limit = VacuumCostLimit;
    1756             : 
    1757             :         /* Only balance limit if no cost-related storage parameters specified */
    1758      535824 :         if (pg_atomic_unlocked_test_flag(&MyWorkerInfo->wi_dobalance))
    1759           0 :             return;
    1760             : 
    1761             :         Assert(vacuum_cost_limit > 0);
    1762             : 
    1763      535824 :         nworkers_for_balance = pg_atomic_read_u32(&AutoVacuumShmem->av_nworkersForBalance);
    1764             : 
    1765             :         /* There is at least 1 autovac worker (this worker) */
    1766      535824 :         if (nworkers_for_balance <= 0)
    1767           0 :             elog(ERROR, "nworkers_for_balance must be > 0");
    1768             : 
    1769      535824 :         vacuum_cost_limit = Max(vacuum_cost_limit / nworkers_for_balance, 1);
    1770             :     }
    1771             : }
    1772             : 
    1773             : /*
    1774             :  * autovac_recalculate_workers_for_balance
    1775             :  *      Recalculate the number of workers to consider, given cost-related
    1776             :  *      storage parameters and the current number of active workers.
    1777             :  *
    1778             :  * Caller must hold the AutovacuumLock in at least shared mode to access
    1779             :  * worker->wi_proc.
    1780             :  */
    1781             : static void
    1782      266858 : autovac_recalculate_workers_for_balance(void)
    1783             : {
    1784             :     dlist_iter  iter;
    1785             :     int         orig_nworkers_for_balance;
    1786      266858 :     int         nworkers_for_balance = 0;
    1787             : 
    1788             :     Assert(LWLockHeldByMe(AutovacuumLock));
    1789             : 
    1790      266858 :     orig_nworkers_for_balance =
    1791      266858 :         pg_atomic_read_u32(&AutoVacuumShmem->av_nworkersForBalance);
    1792             : 
    1793      827904 :     dlist_foreach(iter, &AutoVacuumShmem->av_runningWorkers)
    1794             :     {
    1795      561046 :         WorkerInfo  worker = dlist_container(WorkerInfoData, wi_links, iter.cur);
    1796             : 
    1797     1122092 :         if (worker->wi_proc == NULL ||
    1798      561046 :             pg_atomic_unlocked_test_flag(&worker->wi_dobalance))
    1799       12144 :             continue;
    1800             : 
    1801      548902 :         nworkers_for_balance++;
    1802             :     }
    1803             : 
    1804      266858 :     if (nworkers_for_balance != orig_nworkers_for_balance)
    1805        5110 :         pg_atomic_write_u32(&AutoVacuumShmem->av_nworkersForBalance,
    1806             :                             nworkers_for_balance);
    1807      266858 : }
    1808             : 
    1809             : /*
    1810             :  * get_database_list
    1811             :  *      Return a list of all databases found in pg_database.
    1812             :  *
    1813             :  * The list and associated data is allocated in the caller's memory context,
    1814             :  * which is in charge of ensuring that it's properly cleaned up afterwards.
    1815             :  *
    1816             :  * Note: this is the only function in which the autovacuum launcher uses a
    1817             :  * transaction.  Although we aren't attached to any particular database and
    1818             :  * therefore can't access most catalogs, we do have enough infrastructure
    1819             :  * to do a seqscan on pg_database.
    1820             :  */
    1821             : static List *
    1822        5840 : get_database_list(void)
    1823             : {
    1824        5840 :     List       *dblist = NIL;
    1825             :     Relation    rel;
    1826             :     TableScanDesc scan;
    1827             :     HeapTuple   tup;
    1828             :     MemoryContext resultcxt;
    1829             : 
    1830             :     /* This is the context that we will allocate our output data in */
    1831        5840 :     resultcxt = CurrentMemoryContext;
    1832             : 
    1833             :     /*
    1834             :      * Start a transaction so we can access pg_database.
    1835             :      */
    1836        5840 :     StartTransactionCommand();
    1837             : 
    1838        5840 :     rel = table_open(DatabaseRelationId, AccessShareLock);
    1839        5840 :     scan = table_beginscan_catalog(rel, 0, NULL);
    1840             : 
    1841       23860 :     while (HeapTupleIsValid(tup = heap_getnext(scan, ForwardScanDirection)))
    1842             :     {
    1843       18020 :         Form_pg_database pgdatabase = (Form_pg_database) GETSTRUCT(tup);
    1844             :         avw_dbase  *avdb;
    1845             :         MemoryContext oldcxt;
    1846             : 
    1847             :         /*
    1848             :          * If database has partially been dropped, we can't, nor need to,
    1849             :          * vacuum it.
    1850             :          */
    1851       18020 :         if (database_is_invalid_form(pgdatabase))
    1852             :         {
    1853          12 :             elog(DEBUG2,
    1854             :                  "autovacuum: skipping invalid database \"%s\"",
    1855             :                  NameStr(pgdatabase->datname));
    1856          12 :             continue;
    1857             :         }
    1858             : 
    1859             :         /*
    1860             :          * Allocate our results in the caller's context, not the
    1861             :          * transaction's. We do this inside the loop, and restore the original
    1862             :          * context at the end, so that leaky things like heap_getnext() are
    1863             :          * not called in a potentially long-lived context.
    1864             :          */
    1865       18008 :         oldcxt = MemoryContextSwitchTo(resultcxt);
    1866             : 
    1867       18008 :         avdb = (avw_dbase *) palloc(sizeof(avw_dbase));
    1868             : 
    1869       18008 :         avdb->adw_datid = pgdatabase->oid;
    1870       18008 :         avdb->adw_name = pstrdup(NameStr(pgdatabase->datname));
    1871       18008 :         avdb->adw_frozenxid = pgdatabase->datfrozenxid;
    1872       18008 :         avdb->adw_minmulti = pgdatabase->datminmxid;
    1873             :         /* this gets set later: */
    1874       18008 :         avdb->adw_entry = NULL;
    1875             : 
    1876       18008 :         dblist = lappend(dblist, avdb);
    1877       18008 :         MemoryContextSwitchTo(oldcxt);
    1878             :     }
    1879             : 
    1880        5840 :     table_endscan(scan);
    1881        5840 :     table_close(rel, AccessShareLock);
    1882             : 
    1883        5840 :     CommitTransactionCommand();
    1884             : 
    1885             :     /* Be sure to restore caller's memory context */
    1886        5840 :     MemoryContextSwitchTo(resultcxt);
    1887             : 
    1888        5840 :     return dblist;
    1889             : }
    1890             : 
    1891             : /*
    1892             :  * Process a database table-by-table
    1893             :  *
    1894             :  * Note that CHECK_FOR_INTERRUPTS is supposed to be used in certain spots in
    1895             :  * order not to ignore shutdown commands for too long.
    1896             :  */
    1897             : static void
    1898        4732 : do_autovacuum(void)
    1899             : {
    1900             :     Relation    classRel;
    1901             :     HeapTuple   tuple;
    1902             :     TableScanDesc relScan;
    1903             :     Form_pg_database dbForm;
    1904        4732 :     List       *table_oids = NIL;
    1905        4732 :     List       *orphan_oids = NIL;
    1906             :     HASHCTL     ctl;
    1907             :     HTAB       *table_toast_map;
    1908             :     ListCell   *volatile cell;
    1909             :     BufferAccessStrategy bstrategy;
    1910             :     ScanKeyData key;
    1911             :     TupleDesc   pg_class_desc;
    1912             :     int         effective_multixact_freeze_max_age;
    1913        4732 :     bool        did_vacuum = false;
    1914        4732 :     bool        found_concurrent_worker = false;
    1915             :     int         i;
    1916             : 
    1917             :     /*
    1918             :      * StartTransactionCommand and CommitTransactionCommand will automatically
    1919             :      * switch to other contexts.  We need this one to keep the list of
    1920             :      * relations to vacuum/analyze across transactions.
    1921             :      */
    1922        4732 :     AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,
    1923             :                                           "Autovacuum worker",
    1924             :                                           ALLOCSET_DEFAULT_SIZES);
    1925        4732 :     MemoryContextSwitchTo(AutovacMemCxt);
    1926             : 
    1927             :     /* Start a transaction so our commands have one to play into. */
    1928        4732 :     StartTransactionCommand();
    1929             : 
    1930             :     /*
    1931             :      * This injection point is put in a transaction block to work with a wait
    1932             :      * that uses a condition variable.
    1933             :      */
    1934        4732 :     INJECTION_POINT("autovacuum-worker-start", NULL);
    1935             : 
    1936             :     /*
    1937             :      * Compute the multixact age for which freezing is urgent.  This is
    1938             :      * normally autovacuum_multixact_freeze_max_age, but may be less if we are
    1939             :      * short of multixact member space.
    1940             :      */
    1941        4730 :     effective_multixact_freeze_max_age = MultiXactMemberFreezeThreshold();
    1942             : 
    1943             :     /*
    1944             :      * Find the pg_database entry and select the default freeze ages. We use
    1945             :      * zero in template and nonconnectable databases, else the system-wide
    1946             :      * default.
    1947             :      */
    1948        4730 :     tuple = SearchSysCache1(DATABASEOID, ObjectIdGetDatum(MyDatabaseId));
    1949        4730 :     if (!HeapTupleIsValid(tuple))
    1950           0 :         elog(ERROR, "cache lookup failed for database %u", MyDatabaseId);
    1951        4730 :     dbForm = (Form_pg_database) GETSTRUCT(tuple);
    1952             : 
    1953        4730 :     if (dbForm->datistemplate || !dbForm->datallowconn)
    1954             :     {
    1955        1740 :         default_freeze_min_age = 0;
    1956        1740 :         default_freeze_table_age = 0;
    1957        1740 :         default_multixact_freeze_min_age = 0;
    1958        1740 :         default_multixact_freeze_table_age = 0;
    1959             :     }
    1960             :     else
    1961             :     {
    1962        2990 :         default_freeze_min_age = vacuum_freeze_min_age;
    1963        2990 :         default_freeze_table_age = vacuum_freeze_table_age;
    1964        2990 :         default_multixact_freeze_min_age = vacuum_multixact_freeze_min_age;
    1965        2990 :         default_multixact_freeze_table_age = vacuum_multixact_freeze_table_age;
    1966             :     }
    1967             : 
    1968        4730 :     ReleaseSysCache(tuple);
    1969             : 
    1970             :     /* StartTransactionCommand changed elsewhere */
    1971        4730 :     MemoryContextSwitchTo(AutovacMemCxt);
    1972             : 
    1973        4730 :     classRel = table_open(RelationRelationId, AccessShareLock);
    1974             : 
    1975             :     /* create a copy so we can use it after closing pg_class */
    1976        4730 :     pg_class_desc = CreateTupleDescCopy(RelationGetDescr(classRel));
    1977             : 
    1978             :     /* create hash table for toast <-> main relid mapping */
    1979        4730 :     ctl.keysize = sizeof(Oid);
    1980        4730 :     ctl.entrysize = sizeof(av_relation);
    1981             : 
    1982        4730 :     table_toast_map = hash_create("TOAST to main relid map",
    1983             :                                   100,
    1984             :                                   &ctl,
    1985             :                                   HASH_ELEM | HASH_BLOBS);
    1986             : 
    1987             :     /*
    1988             :      * Scan pg_class to determine which tables to vacuum.
    1989             :      *
    1990             :      * We do this in two passes: on the first one we collect the list of plain
    1991             :      * relations and materialized views, and on the second one we collect
    1992             :      * TOAST tables. The reason for doing the second pass is that during it we
    1993             :      * want to use the main relation's pg_class.reloptions entry if the TOAST
    1994             :      * table does not have any, and we cannot obtain it unless we know
    1995             :      * beforehand what's the main table OID.
    1996             :      *
    1997             :      * We need to check TOAST tables separately because in cases with short,
    1998             :      * wide tables there might be proportionally much more activity in the
    1999             :      * TOAST table than in its parent.
    2000             :      */
    2001        4730 :     relScan = table_beginscan_catalog(classRel, 0, NULL);
    2002             : 
    2003             :     /*
    2004             :      * On the first pass, we collect main tables to vacuum, and also the main
    2005             :      * table relid to TOAST relid mapping.
    2006             :      */
    2007     2000074 :     while ((tuple = heap_getnext(relScan, ForwardScanDirection)) != NULL)
    2008             :     {
    2009     1995344 :         Form_pg_class classForm = (Form_pg_class) GETSTRUCT(tuple);
    2010             :         PgStat_StatTabEntry *tabentry;
    2011             :         AutoVacOpts *relopts;
    2012             :         Oid         relid;
    2013             :         bool        dovacuum;
    2014             :         bool        doanalyze;
    2015             :         bool        wraparound;
    2016             : 
    2017     1995344 :         if (classForm->relkind != RELKIND_RELATION &&
    2018     1664842 :             classForm->relkind != RELKIND_MATVIEW)
    2019     1664746 :             continue;
    2020             : 
    2021      330616 :         relid = classForm->oid;
    2022             : 
    2023             :         /*
    2024             :          * Check if it is a temp table (presumably, of some other backend's).
    2025             :          * We cannot safely process other backends' temp tables.
    2026             :          */
    2027      330616 :         if (classForm->relpersistence == RELPERSISTENCE_TEMP)
    2028             :         {
    2029             :             /*
    2030             :              * We just ignore it if the owning backend is still active and
    2031             :              * using the temporary schema.  Also, for safety, ignore it if the
    2032             :              * namespace doesn't exist or isn't a temp namespace after all.
    2033             :              */
    2034          18 :             if (checkTempNamespaceStatus(classForm->relnamespace) == TEMP_NAMESPACE_IDLE)
    2035             :             {
    2036             :                 /*
    2037             :                  * The table seems to be orphaned -- although it might be that
    2038             :                  * the owning backend has already deleted it and exited; our
    2039             :                  * pg_class scan snapshot is not necessarily up-to-date
    2040             :                  * anymore, so we could be looking at a committed-dead entry.
    2041             :                  * Remember it so we can try to delete it later.
    2042             :                  */
    2043           0 :                 orphan_oids = lappend_oid(orphan_oids, relid);
    2044             :             }
    2045          18 :             continue;
    2046             :         }
    2047             : 
    2048             :         /* Fetch reloptions and the pgstat entry for this table */
    2049      330598 :         relopts = extract_autovac_opts(tuple, pg_class_desc);
    2050      330598 :         tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
    2051             :                                                   relid);
    2052             : 
    2053             :         /* Check if it needs vacuum or analyze */
    2054      330598 :         relation_needs_vacanalyze(relid, relopts, classForm, tabentry,
    2055             :                                   effective_multixact_freeze_max_age,
    2056             :                                   &dovacuum, &doanalyze, &wraparound);
    2057             : 
    2058             :         /* Relations that need work are added to table_oids */
    2059      330598 :         if (dovacuum || doanalyze)
    2060      166860 :             table_oids = lappend_oid(table_oids, relid);
    2061             : 
    2062             :         /*
    2063             :          * Remember TOAST associations for the second pass.  Note: we must do
    2064             :          * this whether or not the table is going to be vacuumed, because we
    2065             :          * don't automatically vacuum toast tables along the parent table.
    2066             :          */
    2067      330598 :         if (OidIsValid(classForm->reltoastrelid))
    2068             :         {
    2069             :             av_relation *hentry;
    2070             :             bool        found;
    2071             : 
    2072      380872 :             hentry = hash_search(table_toast_map,
    2073      190436 :                                  &classForm->reltoastrelid,
    2074             :                                  HASH_ENTER, &found);
    2075             : 
    2076      190436 :             if (!found)
    2077             :             {
    2078             :                 /* hash_search already filled in the key */
    2079      190436 :                 hentry->ar_relid = relid;
    2080      190436 :                 hentry->ar_hasrelopts = false;
    2081      190436 :                 if (relopts != NULL)
    2082             :                 {
    2083        4266 :                     hentry->ar_hasrelopts = true;
    2084        4266 :                     memcpy(&hentry->ar_reloptions, relopts,
    2085             :                            sizeof(AutoVacOpts));
    2086             :                 }
    2087             :             }
    2088             :         }
    2089             : 
    2090             :         /* Release stuff to avoid per-relation leakage */
    2091      330598 :         if (relopts)
    2092        4340 :             pfree(relopts);
    2093      330598 :         if (tabentry)
    2094      325632 :             pfree(tabentry);
    2095             :     }
    2096             : 
    2097        4730 :     table_endscan(relScan);
    2098             : 
    2099             :     /* second pass: check TOAST tables */
    2100        4730 :     ScanKeyInit(&key,
    2101             :                 Anum_pg_class_relkind,
    2102             :                 BTEqualStrategyNumber, F_CHAREQ,
    2103             :                 CharGetDatum(RELKIND_TOASTVALUE));
    2104             : 
    2105        4730 :     relScan = table_beginscan_catalog(classRel, 1, &key);
    2106      195168 :     while ((tuple = heap_getnext(relScan, ForwardScanDirection)) != NULL)
    2107             :     {
    2108      190438 :         Form_pg_class classForm = (Form_pg_class) GETSTRUCT(tuple);
    2109             :         PgStat_StatTabEntry *tabentry;
    2110             :         Oid         relid;
    2111             :         AutoVacOpts *relopts;
    2112      190438 :         bool        free_relopts = false;
    2113             :         bool        dovacuum;
    2114             :         bool        doanalyze;
    2115             :         bool        wraparound;
    2116             : 
    2117             :         /*
    2118             :          * We cannot safely process other backends' temp tables, so skip 'em.
    2119             :          */
    2120      190438 :         if (classForm->relpersistence == RELPERSISTENCE_TEMP)
    2121           2 :             continue;
    2122             : 
    2123      190436 :         relid = classForm->oid;
    2124             : 
    2125             :         /*
    2126             :          * fetch reloptions -- if this toast table does not have them, try the
    2127             :          * main rel
    2128             :          */
    2129      190436 :         relopts = extract_autovac_opts(tuple, pg_class_desc);
    2130      190436 :         if (relopts)
    2131           2 :             free_relopts = true;
    2132             :         else
    2133             :         {
    2134             :             av_relation *hentry;
    2135             :             bool        found;
    2136             : 
    2137      190434 :             hentry = hash_search(table_toast_map, &relid, HASH_FIND, &found);
    2138      190434 :             if (found && hentry->ar_hasrelopts)
    2139        4264 :                 relopts = &hentry->ar_reloptions;
    2140             :         }
    2141             : 
    2142             :         /* Fetch the pgstat entry for this table */
    2143      190436 :         tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
    2144             :                                                   relid);
    2145             : 
    2146      190436 :         relation_needs_vacanalyze(relid, relopts, classForm, tabentry,
    2147             :                                   effective_multixact_freeze_max_age,
    2148             :                                   &dovacuum, &doanalyze, &wraparound);
    2149             : 
    2150             :         /* ignore analyze for toast tables */
    2151      190436 :         if (dovacuum)
    2152       96484 :             table_oids = lappend_oid(table_oids, relid);
    2153             : 
    2154             :         /* Release stuff to avoid leakage */
    2155      190436 :         if (free_relopts)
    2156           2 :             pfree(relopts);
    2157      190436 :         if (tabentry)
    2158      186856 :             pfree(tabentry);
    2159             :     }
    2160             : 
    2161        4730 :     table_endscan(relScan);
    2162        4730 :     table_close(classRel, AccessShareLock);
    2163             : 
    2164             :     /*
    2165             :      * Recheck orphan temporary tables, and if they still seem orphaned, drop
    2166             :      * them.  We'll eat a transaction per dropped table, which might seem
    2167             :      * excessive, but we should only need to do anything as a result of a
    2168             :      * previous backend crash, so this should not happen often enough to
    2169             :      * justify "optimizing".  Using separate transactions ensures that we
    2170             :      * don't bloat the lock table if there are many temp tables to be dropped,
    2171             :      * and it ensures that we don't lose work if a deletion attempt fails.
    2172             :      */
    2173        4730 :     foreach(cell, orphan_oids)
    2174             :     {
    2175           0 :         Oid         relid = lfirst_oid(cell);
    2176             :         Form_pg_class classForm;
    2177             :         ObjectAddress object;
    2178             : 
    2179             :         /*
    2180             :          * Check for user-requested abort.
    2181             :          */
    2182           0 :         CHECK_FOR_INTERRUPTS();
    2183             : 
    2184             :         /*
    2185             :          * Try to lock the table.  If we can't get the lock immediately,
    2186             :          * somebody else is using (or dropping) the table, so it's not our
    2187             :          * concern anymore.  Having the lock prevents race conditions below.
    2188             :          */
    2189           0 :         if (!ConditionalLockRelationOid(relid, AccessExclusiveLock))
    2190           0 :             continue;
    2191             : 
    2192             :         /*
    2193             :          * Re-fetch the pg_class tuple and re-check whether it still seems to
    2194             :          * be an orphaned temp table.  If it's not there or no longer the same
    2195             :          * relation, ignore it.
    2196             :          */
    2197           0 :         tuple = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relid));
    2198           0 :         if (!HeapTupleIsValid(tuple))
    2199             :         {
    2200             :             /* be sure to drop useless lock so we don't bloat lock table */
    2201           0 :             UnlockRelationOid(relid, AccessExclusiveLock);
    2202           0 :             continue;
    2203             :         }
    2204           0 :         classForm = (Form_pg_class) GETSTRUCT(tuple);
    2205             : 
    2206             :         /*
    2207             :          * Make all the same tests made in the loop above.  In event of OID
    2208             :          * counter wraparound, the pg_class entry we have now might be
    2209             :          * completely unrelated to the one we saw before.
    2210             :          */
    2211           0 :         if (!((classForm->relkind == RELKIND_RELATION ||
    2212           0 :                classForm->relkind == RELKIND_MATVIEW) &&
    2213           0 :               classForm->relpersistence == RELPERSISTENCE_TEMP))
    2214             :         {
    2215           0 :             UnlockRelationOid(relid, AccessExclusiveLock);
    2216           0 :             continue;
    2217             :         }
    2218             : 
    2219           0 :         if (checkTempNamespaceStatus(classForm->relnamespace) != TEMP_NAMESPACE_IDLE)
    2220             :         {
    2221           0 :             UnlockRelationOid(relid, AccessExclusiveLock);
    2222           0 :             continue;
    2223             :         }
    2224             : 
    2225             :         /*
    2226             :          * Try to lock the temp namespace, too.  Even though we have lock on
    2227             :          * the table itself, there's a risk of deadlock against an incoming
    2228             :          * backend trying to clean out the temp namespace, in case this table
    2229             :          * has dependencies (such as sequences) that the backend's
    2230             :          * performDeletion call might visit in a different order.  If we can
    2231             :          * get AccessShareLock on the namespace, that's sufficient to ensure
    2232             :          * we're not running concurrently with RemoveTempRelations.  If we
    2233             :          * can't, back off and let RemoveTempRelations do its thing.
    2234             :          */
    2235           0 :         if (!ConditionalLockDatabaseObject(NamespaceRelationId,
    2236             :                                            classForm->relnamespace, 0,
    2237             :                                            AccessShareLock))
    2238             :         {
    2239           0 :             UnlockRelationOid(relid, AccessExclusiveLock);
    2240           0 :             continue;
    2241             :         }
    2242             : 
    2243             :         /* OK, let's delete it */
    2244           0 :         ereport(LOG,
    2245             :                 (errmsg("autovacuum: dropping orphan temp table \"%s.%s.%s\"",
    2246             :                         get_database_name(MyDatabaseId),
    2247             :                         get_namespace_name(classForm->relnamespace),
    2248             :                         NameStr(classForm->relname))));
    2249             : 
    2250             :         /*
    2251             :          * Deletion might involve TOAST table access, so ensure we have a
    2252             :          * valid snapshot.
    2253             :          */
    2254           0 :         PushActiveSnapshot(GetTransactionSnapshot());
    2255             : 
    2256           0 :         object.classId = RelationRelationId;
    2257           0 :         object.objectId = relid;
    2258           0 :         object.objectSubId = 0;
    2259           0 :         performDeletion(&object, DROP_CASCADE,
    2260             :                         PERFORM_DELETION_INTERNAL |
    2261             :                         PERFORM_DELETION_QUIETLY |
    2262             :                         PERFORM_DELETION_SKIP_EXTENSIONS);
    2263             : 
    2264             :         /*
    2265             :          * To commit the deletion, end current transaction and start a new
    2266             :          * one.  Note this also releases the locks we took.
    2267             :          */
    2268           0 :         PopActiveSnapshot();
    2269           0 :         CommitTransactionCommand();
    2270           0 :         StartTransactionCommand();
    2271             : 
    2272             :         /* StartTransactionCommand changed current memory context */
    2273           0 :         MemoryContextSwitchTo(AutovacMemCxt);
    2274             :     }
    2275             : 
    2276             :     /*
    2277             :      * Optionally, create a buffer access strategy object for VACUUM to use.
    2278             :      * We use the same BufferAccessStrategy object for all tables VACUUMed by
    2279             :      * this worker to prevent autovacuum from blowing out shared buffers.
    2280             :      *
    2281             :      * VacuumBufferUsageLimit being set to 0 results in
    2282             :      * GetAccessStrategyWithSize returning NULL, effectively meaning we can
    2283             :      * use up to all of shared buffers.
    2284             :      *
    2285             :      * If we later enter failsafe mode on any of the tables being vacuumed, we
    2286             :      * will cease use of the BufferAccessStrategy only for that table.
    2287             :      *
    2288             :      * XXX should we consider adding code to adjust the size of this if
    2289             :      * VacuumBufferUsageLimit changes?
    2290             :      */
    2291        4730 :     bstrategy = GetAccessStrategyWithSize(BAS_VACUUM, VacuumBufferUsageLimit);
    2292             : 
    2293             :     /*
    2294             :      * create a memory context to act as fake PortalContext, so that the
    2295             :      * contexts created in the vacuum code are cleaned up for each table.
    2296             :      */
    2297        4730 :     PortalContext = AllocSetContextCreate(AutovacMemCxt,
    2298             :                                           "Autovacuum Portal",
    2299             :                                           ALLOCSET_DEFAULT_SIZES);
    2300             : 
    2301             :     /*
    2302             :      * Perform operations on collected tables.
    2303             :      */
    2304      268074 :     foreach(cell, table_oids)
    2305             :     {
    2306      263344 :         Oid         relid = lfirst_oid(cell);
    2307             :         HeapTuple   classTup;
    2308             :         autovac_table *tab;
    2309             :         bool        isshared;
    2310             :         bool        skipit;
    2311             :         dlist_iter  iter;
    2312             : 
    2313      263344 :         CHECK_FOR_INTERRUPTS();
    2314             : 
    2315             :         /*
    2316             :          * Check for config changes before processing each collected table.
    2317             :          */
    2318      263344 :         if (ConfigReloadPending)
    2319             :         {
    2320           0 :             ConfigReloadPending = false;
    2321           0 :             ProcessConfigFile(PGC_SIGHUP);
    2322             : 
    2323             :             /*
    2324             :              * You might be tempted to bail out if we see autovacuum is now
    2325             :              * disabled.  Must resist that temptation -- this might be a
    2326             :              * for-wraparound emergency worker, in which case that would be
    2327             :              * entirely inappropriate.
    2328             :              */
    2329             :         }
    2330             : 
    2331             :         /*
    2332             :          * Find out whether the table is shared or not.  (It's slightly
    2333             :          * annoying to fetch the syscache entry just for this, but in typical
    2334             :          * cases it adds little cost because table_recheck_autovac would
    2335             :          * refetch the entry anyway.  We could buy that back by copying the
    2336             :          * tuple here and passing it to table_recheck_autovac, but that
    2337             :          * increases the odds of that function working with stale data.)
    2338             :          */
    2339      263344 :         classTup = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
    2340      263344 :         if (!HeapTupleIsValid(classTup))
    2341        1204 :             continue;           /* somebody deleted the rel, forget it */
    2342      263344 :         isshared = ((Form_pg_class) GETSTRUCT(classTup))->relisshared;
    2343      263344 :         ReleaseSysCache(classTup);
    2344             : 
    2345             :         /*
    2346             :          * Hold schedule lock from here until we've claimed the table.  We
    2347             :          * also need the AutovacuumLock to walk the worker array, but that one
    2348             :          * can just be a shared lock.
    2349             :          */
    2350      263344 :         LWLockAcquire(AutovacuumScheduleLock, LW_EXCLUSIVE);
    2351      263344 :         LWLockAcquire(AutovacuumLock, LW_SHARED);
    2352             : 
    2353             :         /*
    2354             :          * Check whether the table is being vacuumed concurrently by another
    2355             :          * worker.
    2356             :          */
    2357      263344 :         skipit = false;
    2358      822784 :         dlist_foreach(iter, &AutoVacuumShmem->av_runningWorkers)
    2359             :         {
    2360      560644 :             WorkerInfo  worker = dlist_container(WorkerInfoData, wi_links, iter.cur);
    2361             : 
    2362             :             /* ignore myself */
    2363      560644 :             if (worker == MyWorkerInfo)
    2364      262786 :                 continue;
    2365             : 
    2366             :             /* ignore workers in other databases (unless table is shared) */
    2367      297858 :             if (!worker->wi_sharedrel && worker->wi_dboid != MyDatabaseId)
    2368        1344 :                 continue;
    2369             : 
    2370      296514 :             if (worker->wi_tableoid == relid)
    2371             :             {
    2372        1204 :                 skipit = true;
    2373        1204 :                 found_concurrent_worker = true;
    2374        1204 :                 break;
    2375             :             }
    2376             :         }
    2377      263344 :         LWLockRelease(AutovacuumLock);
    2378      263344 :         if (skipit)
    2379             :         {
    2380        1204 :             LWLockRelease(AutovacuumScheduleLock);
    2381        1204 :             continue;
    2382             :         }
    2383             : 
    2384             :         /*
    2385             :          * Store the table's OID in shared memory before releasing the
    2386             :          * schedule lock, so that other workers don't try to vacuum it
    2387             :          * concurrently.  (We claim it here so as not to hold
    2388             :          * AutovacuumScheduleLock while rechecking the stats.)
    2389             :          */
    2390      262140 :         MyWorkerInfo->wi_tableoid = relid;
    2391      262140 :         MyWorkerInfo->wi_sharedrel = isshared;
    2392      262140 :         LWLockRelease(AutovacuumScheduleLock);
    2393             : 
    2394             :         /*
    2395             :          * Check whether pgstat data still says we need to vacuum this table.
    2396             :          * It could have changed if something else processed the table while
    2397             :          * we weren't looking. This doesn't entirely close the race condition,
    2398             :          * but it is very small.
    2399             :          */
    2400      262140 :         MemoryContextSwitchTo(AutovacMemCxt);
    2401      262140 :         tab = table_recheck_autovac(relid, table_toast_map, pg_class_desc,
    2402             :                                     effective_multixact_freeze_max_age);
    2403      262140 :         if (tab == NULL)
    2404             :         {
    2405             :             /* someone else vacuumed the table, or it went away */
    2406           0 :             LWLockAcquire(AutovacuumScheduleLock, LW_EXCLUSIVE);
    2407           0 :             MyWorkerInfo->wi_tableoid = InvalidOid;
    2408           0 :             MyWorkerInfo->wi_sharedrel = false;
    2409           0 :             LWLockRelease(AutovacuumScheduleLock);
    2410           0 :             continue;
    2411             :         }
    2412             : 
    2413             :         /*
    2414             :          * Save the cost-related storage parameter values in global variables
    2415             :          * for reference when updating vacuum_cost_delay and vacuum_cost_limit
    2416             :          * during vacuuming this table.
    2417             :          */
    2418      262140 :         av_storage_param_cost_delay = tab->at_storage_param_vac_cost_delay;
    2419      262140 :         av_storage_param_cost_limit = tab->at_storage_param_vac_cost_limit;
    2420             : 
    2421             :         /*
    2422             :          * We only expect this worker to ever set the flag, so don't bother
    2423             :          * checking the return value. We shouldn't have to retry.
    2424             :          */
    2425      262140 :         if (tab->at_dobalance)
    2426      262140 :             pg_atomic_test_set_flag(&MyWorkerInfo->wi_dobalance);
    2427             :         else
    2428           0 :             pg_atomic_clear_flag(&MyWorkerInfo->wi_dobalance);
    2429             : 
    2430      262140 :         LWLockAcquire(AutovacuumLock, LW_SHARED);
    2431      262140 :         autovac_recalculate_workers_for_balance();
    2432      262140 :         LWLockRelease(AutovacuumLock);
    2433             : 
    2434             :         /*
    2435             :          * We wait until this point to update cost delay and cost limit
    2436             :          * values, even though we reloaded the configuration file above, so
    2437             :          * that we can take into account the cost-related storage parameters.
    2438             :          */
    2439      262140 :         VacuumUpdateCosts();
    2440             : 
    2441             : 
    2442             :         /* clean up memory before each iteration */
    2443      262140 :         MemoryContextReset(PortalContext);
    2444             : 
    2445             :         /*
    2446             :          * Save the relation name for a possible error message, to avoid a
    2447             :          * catalog lookup in case of an error.  If any of these return NULL,
    2448             :          * then the relation has been dropped since last we checked; skip it.
    2449             :          * Note: they must live in a long-lived memory context because we call
    2450             :          * vacuum and analyze in different transactions.
    2451             :          */
    2452             : 
    2453      262140 :         tab->at_relname = get_rel_name(tab->at_relid);
    2454      262140 :         tab->at_nspname = get_namespace_name(get_rel_namespace(tab->at_relid));
    2455      262140 :         tab->at_datname = get_database_name(MyDatabaseId);
    2456      262140 :         if (!tab->at_relname || !tab->at_nspname || !tab->at_datname)
    2457           0 :             goto deleted;
    2458             : 
    2459             :         /*
    2460             :          * We will abort vacuuming the current table if something errors out,
    2461             :          * and continue with the next one in schedule; in particular, this
    2462             :          * happens if we are interrupted with SIGINT.
    2463             :          */
    2464      262140 :         PG_TRY();
    2465             :         {
    2466             :             /* Use PortalContext for any per-table allocations */
    2467      262140 :             MemoryContextSwitchTo(PortalContext);
    2468             : 
    2469             :             /* have at it */
    2470      262140 :             autovacuum_do_vac_analyze(tab, bstrategy);
    2471             : 
    2472             :             /*
    2473             :              * Clear a possible query-cancel signal, to avoid a late reaction
    2474             :              * to an automatically-sent signal because of vacuuming the
    2475             :              * current table (we're done with it, so it would make no sense to
    2476             :              * cancel at this point.)
    2477             :              */
    2478      262140 :             QueryCancelPending = false;
    2479             :         }
    2480           0 :         PG_CATCH();
    2481             :         {
    2482             :             /*
    2483             :              * Abort the transaction, start a new one, and proceed with the
    2484             :              * next table in our list.
    2485             :              */
    2486           0 :             HOLD_INTERRUPTS();
    2487           0 :             if (tab->at_params.options & VACOPT_VACUUM)
    2488           0 :                 errcontext("automatic vacuum of table \"%s.%s.%s\"",
    2489             :                            tab->at_datname, tab->at_nspname, tab->at_relname);
    2490             :             else
    2491           0 :                 errcontext("automatic analyze of table \"%s.%s.%s\"",
    2492             :                            tab->at_datname, tab->at_nspname, tab->at_relname);
    2493           0 :             EmitErrorReport();
    2494             : 
    2495             :             /* this resets ProcGlobal->statusFlags[i] too */
    2496           0 :             AbortOutOfAnyTransaction();
    2497           0 :             FlushErrorState();
    2498           0 :             MemoryContextReset(PortalContext);
    2499             : 
    2500             :             /* restart our transaction for the following operations */
    2501           0 :             StartTransactionCommand();
    2502           0 :             RESUME_INTERRUPTS();
    2503             :         }
    2504      262140 :         PG_END_TRY();
    2505             : 
    2506             :         /* Make sure we're back in AutovacMemCxt */
    2507      262140 :         MemoryContextSwitchTo(AutovacMemCxt);
    2508             : 
    2509      262140 :         did_vacuum = true;
    2510             : 
    2511             :         /* ProcGlobal->statusFlags[i] are reset at the next end of xact */
    2512             : 
    2513             :         /* be tidy */
    2514      262140 : deleted:
    2515      262140 :         if (tab->at_datname != NULL)
    2516      262140 :             pfree(tab->at_datname);
    2517      262140 :         if (tab->at_nspname != NULL)
    2518      262140 :             pfree(tab->at_nspname);
    2519      262140 :         if (tab->at_relname != NULL)
    2520      262140 :             pfree(tab->at_relname);
    2521      262140 :         pfree(tab);
    2522             : 
    2523             :         /*
    2524             :          * Remove my info from shared memory.  We set wi_dobalance on the
    2525             :          * assumption that we are more likely than not to vacuum a table with
    2526             :          * no cost-related storage parameters next, so we want to claim our
    2527             :          * share of I/O as soon as possible to avoid thrashing the global
    2528             :          * balance.
    2529             :          */
    2530      262140 :         LWLockAcquire(AutovacuumScheduleLock, LW_EXCLUSIVE);
    2531      262140 :         MyWorkerInfo->wi_tableoid = InvalidOid;
    2532      262140 :         MyWorkerInfo->wi_sharedrel = false;
    2533      262140 :         LWLockRelease(AutovacuumScheduleLock);
    2534      262140 :         pg_atomic_test_set_flag(&MyWorkerInfo->wi_dobalance);
    2535             :     }
    2536             : 
    2537        4730 :     list_free(table_oids);
    2538             : 
    2539             :     /*
    2540             :      * Perform additional work items, as requested by backends.
    2541             :      */
    2542        4730 :     LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    2543     1215610 :     for (i = 0; i < NUM_WORKITEMS; i++)
    2544             :     {
    2545     1210880 :         AutoVacuumWorkItem *workitem = &AutoVacuumShmem->av_workItems[i];
    2546             : 
    2547     1210880 :         if (!workitem->avw_used)
    2548     1210874 :             continue;
    2549           6 :         if (workitem->avw_active)
    2550           0 :             continue;
    2551           6 :         if (workitem->avw_database != MyDatabaseId)
    2552           0 :             continue;
    2553             : 
    2554             :         /* claim this one, and release lock while performing it */
    2555           6 :         workitem->avw_active = true;
    2556           6 :         LWLockRelease(AutovacuumLock);
    2557             : 
    2558           6 :         perform_work_item(workitem);
    2559             : 
    2560             :         /*
    2561             :          * Check for config changes before acquiring lock for further jobs.
    2562             :          */
    2563           6 :         CHECK_FOR_INTERRUPTS();
    2564           6 :         if (ConfigReloadPending)
    2565             :         {
    2566           0 :             ConfigReloadPending = false;
    2567           0 :             ProcessConfigFile(PGC_SIGHUP);
    2568           0 :             VacuumUpdateCosts();
    2569             :         }
    2570             : 
    2571           6 :         LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    2572             : 
    2573             :         /* and mark it done */
    2574           6 :         workitem->avw_active = false;
    2575           6 :         workitem->avw_used = false;
    2576             :     }
    2577        4730 :     LWLockRelease(AutovacuumLock);
    2578             : 
    2579             :     /*
    2580             :      * We leak table_toast_map here (among other things), but since we're
    2581             :      * going away soon, it's not a problem normally.  But when using Valgrind,
    2582             :      * release some stuff to reduce complaints about leaked storage.
    2583             :      */
    2584             : #ifdef USE_VALGRIND
    2585             :     hash_destroy(table_toast_map);
    2586             :     FreeTupleDesc(pg_class_desc);
    2587             :     if (bstrategy)
    2588             :         pfree(bstrategy);
    2589             : #endif
    2590             : 
    2591             :     /* Run the rest in xact context, mainly to avoid Valgrind leak warnings */
    2592        4730 :     MemoryContextSwitchTo(TopTransactionContext);
    2593             : 
    2594             :     /*
    2595             :      * Update pg_database.datfrozenxid, and truncate pg_xact if possible. We
    2596             :      * only need to do this once, not after each table.
    2597             :      *
    2598             :      * Even if we didn't vacuum anything, it may still be important to do
    2599             :      * this, because one indirect effect of vac_update_datfrozenxid() is to
    2600             :      * update TransamVariables->xidVacLimit.  That might need to be done even
    2601             :      * if we haven't vacuumed anything, because relations with older
    2602             :      * relfrozenxid values or other databases with older datfrozenxid values
    2603             :      * might have been dropped, allowing xidVacLimit to advance.
    2604             :      *
    2605             :      * However, it's also important not to do this blindly in all cases,
    2606             :      * because when autovacuum=off this will restart the autovacuum launcher.
    2607             :      * If we're not careful, an infinite loop can result, where workers find
    2608             :      * no work to do and restart the launcher, which starts another worker in
    2609             :      * the same database that finds no work to do.  To prevent that, we skip
    2610             :      * this if (1) we found no work to do and (2) we skipped at least one
    2611             :      * table due to concurrent autovacuum activity.  In that case, the other
    2612             :      * worker has already done it, or will do so when it finishes.
    2613             :      */
    2614        4730 :     if (did_vacuum || !found_concurrent_worker)
    2615        4730 :         vac_update_datfrozenxid();
    2616             : 
    2617             :     /* Finally close out the last transaction. */
    2618        4730 :     CommitTransactionCommand();
    2619        4730 : }
    2620             : 
    2621             : /*
    2622             :  * Execute a previously registered work item.
    2623             :  */
    2624             : static void
    2625           6 : perform_work_item(AutoVacuumWorkItem *workitem)
    2626             : {
    2627           6 :     char       *cur_datname = NULL;
    2628           6 :     char       *cur_nspname = NULL;
    2629           6 :     char       *cur_relname = NULL;
    2630             : 
    2631             :     /*
    2632             :      * Note we do not store table info in MyWorkerInfo, since this is not
    2633             :      * vacuuming proper.
    2634             :      */
    2635             : 
    2636             :     /*
    2637             :      * Save the relation name for a possible error message, to avoid a catalog
    2638             :      * lookup in case of an error.  If any of these return NULL, then the
    2639             :      * relation has been dropped since last we checked; skip it.
    2640             :      */
    2641             :     Assert(CurrentMemoryContext == AutovacMemCxt);
    2642             : 
    2643           6 :     cur_relname = get_rel_name(workitem->avw_relation);
    2644           6 :     cur_nspname = get_namespace_name(get_rel_namespace(workitem->avw_relation));
    2645           6 :     cur_datname = get_database_name(MyDatabaseId);
    2646           6 :     if (!cur_relname || !cur_nspname || !cur_datname)
    2647           0 :         goto deleted2;
    2648             : 
    2649           6 :     autovac_report_workitem(workitem, cur_nspname, cur_relname);
    2650             : 
    2651             :     /* clean up memory before each work item */
    2652           6 :     MemoryContextReset(PortalContext);
    2653             : 
    2654             :     /*
    2655             :      * We will abort the current work item if something errors out, and
    2656             :      * continue with the next one; in particular, this happens if we are
    2657             :      * interrupted with SIGINT.  Note that this means that the work item list
    2658             :      * can be lossy.
    2659             :      */
    2660           6 :     PG_TRY();
    2661             :     {
    2662             :         /* Use PortalContext for any per-work-item allocations */
    2663           6 :         MemoryContextSwitchTo(PortalContext);
    2664             : 
    2665             :         /*
    2666             :          * Have at it.  Functions called here are responsible for any required
    2667             :          * user switch and sandbox.
    2668             :          */
    2669           6 :         switch (workitem->avw_type)
    2670             :         {
    2671           6 :             case AVW_BRINSummarizeRange:
    2672           6 :                 DirectFunctionCall2(brin_summarize_range,
    2673             :                                     ObjectIdGetDatum(workitem->avw_relation),
    2674             :                                     Int64GetDatum((int64) workitem->avw_blockNumber));
    2675           6 :                 break;
    2676           0 :             default:
    2677           0 :                 elog(WARNING, "unrecognized work item found: type %d",
    2678             :                      workitem->avw_type);
    2679           0 :                 break;
    2680             :         }
    2681             : 
    2682             :         /*
    2683             :          * Clear a possible query-cancel signal, to avoid a late reaction to
    2684             :          * an automatically-sent signal because of vacuuming the current table
    2685             :          * (we're done with it, so it would make no sense to cancel at this
    2686             :          * point.)
    2687             :          */
    2688           6 :         QueryCancelPending = false;
    2689             :     }
    2690           0 :     PG_CATCH();
    2691             :     {
    2692             :         /*
    2693             :          * Abort the transaction, start a new one, and proceed with the next
    2694             :          * table in our list.
    2695             :          */
    2696           0 :         HOLD_INTERRUPTS();
    2697           0 :         errcontext("processing work entry for relation \"%s.%s.%s\"",
    2698             :                    cur_datname, cur_nspname, cur_relname);
    2699           0 :         EmitErrorReport();
    2700             : 
    2701             :         /* this resets ProcGlobal->statusFlags[i] too */
    2702           0 :         AbortOutOfAnyTransaction();
    2703           0 :         FlushErrorState();
    2704           0 :         MemoryContextReset(PortalContext);
    2705             : 
    2706             :         /* restart our transaction for the following operations */
    2707           0 :         StartTransactionCommand();
    2708           0 :         RESUME_INTERRUPTS();
    2709             :     }
    2710           6 :     PG_END_TRY();
    2711             : 
    2712             :     /* Make sure we're back in AutovacMemCxt */
    2713           6 :     MemoryContextSwitchTo(AutovacMemCxt);
    2714             : 
    2715             :     /* We intentionally do not set did_vacuum here */
    2716             : 
    2717             :     /* be tidy */
    2718           6 : deleted2:
    2719           6 :     if (cur_datname)
    2720           6 :         pfree(cur_datname);
    2721           6 :     if (cur_nspname)
    2722           6 :         pfree(cur_nspname);
    2723           6 :     if (cur_relname)
    2724           6 :         pfree(cur_relname);
    2725           6 : }
    2726             : 
    2727             : /*
    2728             :  * extract_autovac_opts
    2729             :  *
    2730             :  * Given a relation's pg_class tuple, return a palloc'd copy of the
    2731             :  * AutoVacOpts portion of reloptions, if set; otherwise, return NULL.
    2732             :  *
    2733             :  * Note: callers do not have a relation lock on the table at this point,
    2734             :  * so the table could have been dropped, and its catalog rows gone, after
    2735             :  * we acquired the pg_class row.  If pg_class had a TOAST table, this would
    2736             :  * be a risk; fortunately, it doesn't.
    2737             :  */
    2738             : static AutoVacOpts *
    2739      783174 : extract_autovac_opts(HeapTuple tup, TupleDesc pg_class_desc)
    2740             : {
    2741             :     bytea      *relopts;
    2742             :     AutoVacOpts *av;
    2743             : 
    2744             :     Assert(((Form_pg_class) GETSTRUCT(tup))->relkind == RELKIND_RELATION ||
    2745             :            ((Form_pg_class) GETSTRUCT(tup))->relkind == RELKIND_MATVIEW ||
    2746             :            ((Form_pg_class) GETSTRUCT(tup))->relkind == RELKIND_TOASTVALUE);
    2747             : 
    2748      783174 :     relopts = extractRelOptions(tup, pg_class_desc, NULL);
    2749      783174 :     if (relopts == NULL)
    2750      775448 :         return NULL;
    2751             : 
    2752        7726 :     av = palloc(sizeof(AutoVacOpts));
    2753        7726 :     memcpy(av, &(((StdRdOptions *) relopts)->autovacuum), sizeof(AutoVacOpts));
    2754        7726 :     pfree(relopts);
    2755             : 
    2756        7726 :     return av;
    2757             : }
    2758             : 
    2759             : 
    2760             : /*
    2761             :  * table_recheck_autovac
    2762             :  *
    2763             :  * Recheck whether a table still needs vacuum or analyze.  Return value is a
    2764             :  * valid autovac_table pointer if it does, NULL otherwise.
    2765             :  *
    2766             :  * Note that the returned autovac_table does not have the name fields set.
    2767             :  */
    2768             : static autovac_table *
    2769      262140 : table_recheck_autovac(Oid relid, HTAB *table_toast_map,
    2770             :                       TupleDesc pg_class_desc,
    2771             :                       int effective_multixact_freeze_max_age)
    2772             : {
    2773             :     Form_pg_class classForm;
    2774             :     HeapTuple   classTup;
    2775             :     bool        dovacuum;
    2776             :     bool        doanalyze;
    2777      262140 :     autovac_table *tab = NULL;
    2778             :     bool        wraparound;
    2779             :     AutoVacOpts *avopts;
    2780      262140 :     bool        free_avopts = false;
    2781             : 
    2782             :     /* fetch the relation's relcache entry */
    2783      262140 :     classTup = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relid));
    2784      262140 :     if (!HeapTupleIsValid(classTup))
    2785           0 :         return NULL;
    2786      262140 :     classForm = (Form_pg_class) GETSTRUCT(classTup);
    2787             : 
    2788             :     /*
    2789             :      * Get the applicable reloptions.  If it is a TOAST table, try to get the
    2790             :      * main table reloptions if the toast table itself doesn't have.
    2791             :      */
    2792      262140 :     avopts = extract_autovac_opts(classTup, pg_class_desc);
    2793      262140 :     if (avopts)
    2794        3384 :         free_avopts = true;
    2795      258756 :     else if (classForm->relkind == RELKIND_TOASTVALUE &&
    2796             :              table_toast_map != NULL)
    2797             :     {
    2798             :         av_relation *hentry;
    2799             :         bool        found;
    2800             : 
    2801       96070 :         hentry = hash_search(table_toast_map, &relid, HASH_FIND, &found);
    2802       96070 :         if (found && hentry->ar_hasrelopts)
    2803        3370 :             avopts = &hentry->ar_reloptions;
    2804             :     }
    2805             : 
    2806      262140 :     recheck_relation_needs_vacanalyze(relid, avopts, classForm,
    2807             :                                       effective_multixact_freeze_max_age,
    2808             :                                       &dovacuum, &doanalyze, &wraparound);
    2809             : 
    2810             :     /* OK, it needs something done */
    2811      262140 :     if (doanalyze || dovacuum)
    2812             :     {
    2813             :         int         freeze_min_age;
    2814             :         int         freeze_table_age;
    2815             :         int         multixact_freeze_min_age;
    2816             :         int         multixact_freeze_table_age;
    2817             :         int         log_min_duration;
    2818             : 
    2819             :         /*
    2820             :          * Calculate the vacuum cost parameters and the freeze ages.  If there
    2821             :          * are options set in pg_class.reloptions, use them; in the case of a
    2822             :          * toast table, try the main table too.  Otherwise use the GUC
    2823             :          * defaults, autovacuum's own first and plain vacuum second.
    2824             :          */
    2825             : 
    2826             :         /* -1 in autovac setting means use log_autovacuum_min_duration */
    2827        6754 :         log_min_duration = (avopts && avopts->log_min_duration >= 0)
    2828             :             ? avopts->log_min_duration
    2829      268894 :             : Log_autovacuum_min_duration;
    2830             : 
    2831             :         /* these do not have autovacuum-specific settings */
    2832        6754 :         freeze_min_age = (avopts && avopts->freeze_min_age >= 0)
    2833             :             ? avopts->freeze_min_age
    2834      268894 :             : default_freeze_min_age;
    2835             : 
    2836        6754 :         freeze_table_age = (avopts && avopts->freeze_table_age >= 0)
    2837             :             ? avopts->freeze_table_age
    2838      268894 :             : default_freeze_table_age;
    2839             : 
    2840      268894 :         multixact_freeze_min_age = (avopts &&
    2841        6754 :                                     avopts->multixact_freeze_min_age >= 0)
    2842             :             ? avopts->multixact_freeze_min_age
    2843      268894 :             : default_multixact_freeze_min_age;
    2844             : 
    2845      268894 :         multixact_freeze_table_age = (avopts &&
    2846        6754 :                                       avopts->multixact_freeze_table_age >= 0)
    2847             :             ? avopts->multixact_freeze_table_age
    2848      268894 :             : default_multixact_freeze_table_age;
    2849             : 
    2850      262140 :         tab = palloc(sizeof(autovac_table));
    2851      262140 :         tab->at_relid = relid;
    2852      262140 :         tab->at_sharedrel = classForm->relisshared;
    2853             : 
    2854             :         /*
    2855             :          * Select VACUUM options.  Note we don't say VACOPT_PROCESS_TOAST, so
    2856             :          * that vacuum() skips toast relations.  Also note we tell vacuum() to
    2857             :          * skip vac_update_datfrozenxid(); we'll do that separately.
    2858             :          */
    2859      262140 :         tab->at_params.options =
    2860      262140 :             (dovacuum ? (VACOPT_VACUUM |
    2861             :                          VACOPT_PROCESS_MAIN |
    2862      262140 :                          VACOPT_SKIP_DATABASE_STATS) : 0) |
    2863      262140 :             (doanalyze ? VACOPT_ANALYZE : 0) |
    2864      262140 :             (!wraparound ? VACOPT_SKIP_LOCKED : 0);
    2865             : 
    2866             :         /*
    2867             :          * index_cleanup and truncate are unspecified at first in autovacuum.
    2868             :          * They will be filled in with usable values using their reloptions
    2869             :          * (or reloption defaults) later.
    2870             :          */
    2871      262140 :         tab->at_params.index_cleanup = VACOPTVALUE_UNSPECIFIED;
    2872      262140 :         tab->at_params.truncate = VACOPTVALUE_UNSPECIFIED;
    2873             :         /* As of now, we don't support parallel vacuum for autovacuum */
    2874      262140 :         tab->at_params.nworkers = -1;
    2875      262140 :         tab->at_params.freeze_min_age = freeze_min_age;
    2876      262140 :         tab->at_params.freeze_table_age = freeze_table_age;
    2877      262140 :         tab->at_params.multixact_freeze_min_age = multixact_freeze_min_age;
    2878      262140 :         tab->at_params.multixact_freeze_table_age = multixact_freeze_table_age;
    2879      262140 :         tab->at_params.is_wraparound = wraparound;
    2880      262140 :         tab->at_params.log_min_duration = log_min_duration;
    2881      262140 :         tab->at_params.toast_parent = InvalidOid;
    2882             : 
    2883             :         /*
    2884             :          * Later, in vacuum_rel(), we check reloptions for any
    2885             :          * vacuum_max_eager_freeze_failure_rate override.
    2886             :          */
    2887      262140 :         tab->at_params.max_eager_freeze_failure_rate = vacuum_max_eager_freeze_failure_rate;
    2888      262140 :         tab->at_storage_param_vac_cost_limit = avopts ?
    2889      262140 :             avopts->vacuum_cost_limit : 0;
    2890      262140 :         tab->at_storage_param_vac_cost_delay = avopts ?
    2891      262140 :             avopts->vacuum_cost_delay : -1;
    2892      262140 :         tab->at_relname = NULL;
    2893      262140 :         tab->at_nspname = NULL;
    2894      262140 :         tab->at_datname = NULL;
    2895             : 
    2896             :         /*
    2897             :          * If any of the cost delay parameters has been set individually for
    2898             :          * this table, disable the balancing algorithm.
    2899             :          */
    2900      262140 :         tab->at_dobalance =
    2901      268894 :             !(avopts && (avopts->vacuum_cost_limit > 0 ||
    2902        6754 :                          avopts->vacuum_cost_delay >= 0));
    2903             :     }
    2904             : 
    2905      262140 :     if (free_avopts)
    2906        3384 :         pfree(avopts);
    2907      262140 :     heap_freetuple(classTup);
    2908      262140 :     return tab;
    2909             : }
    2910             : 
    2911             : /*
    2912             :  * recheck_relation_needs_vacanalyze
    2913             :  *
    2914             :  * Subroutine for table_recheck_autovac.
    2915             :  *
    2916             :  * Fetch the pgstat of a relation and recheck whether a relation
    2917             :  * needs to be vacuumed or analyzed.
    2918             :  */
    2919             : static void
    2920      262140 : recheck_relation_needs_vacanalyze(Oid relid,
    2921             :                                   AutoVacOpts *avopts,
    2922             :                                   Form_pg_class classForm,
    2923             :                                   int effective_multixact_freeze_max_age,
    2924             :                                   bool *dovacuum,
    2925             :                                   bool *doanalyze,
    2926             :                                   bool *wraparound)
    2927             : {
    2928             :     PgStat_StatTabEntry *tabentry;
    2929             : 
    2930             :     /* fetch the pgstat table entry */
    2931      262140 :     tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
    2932             :                                               relid);
    2933             : 
    2934      262140 :     relation_needs_vacanalyze(relid, avopts, classForm, tabentry,
    2935             :                               effective_multixact_freeze_max_age,
    2936             :                               dovacuum, doanalyze, wraparound);
    2937             : 
    2938             :     /* Release tabentry to avoid leakage */
    2939      262140 :     if (tabentry)
    2940      261220 :         pfree(tabentry);
    2941             : 
    2942             :     /* ignore ANALYZE for toast tables */
    2943      262140 :     if (classForm->relkind == RELKIND_TOASTVALUE)
    2944       96070 :         *doanalyze = false;
    2945      262140 : }
    2946             : 
    2947             : /*
    2948             :  * relation_needs_vacanalyze
    2949             :  *
    2950             :  * Check whether a relation needs to be vacuumed or analyzed; return each into
    2951             :  * "dovacuum" and "doanalyze", respectively.  Also return whether the vacuum is
    2952             :  * being forced because of Xid or multixact wraparound.
    2953             :  *
    2954             :  * relopts is a pointer to the AutoVacOpts options (either for itself in the
    2955             :  * case of a plain table, or for either itself or its parent table in the case
    2956             :  * of a TOAST table), NULL if none; tabentry is the pgstats entry, which can be
    2957             :  * NULL.
    2958             :  *
    2959             :  * A table needs to be vacuumed if the number of dead tuples exceeds a
    2960             :  * threshold.  This threshold is calculated as
    2961             :  *
    2962             :  * threshold = vac_base_thresh + vac_scale_factor * reltuples
    2963             :  * if (threshold > vac_max_thresh)
    2964             :  *     threshold = vac_max_thresh;
    2965             :  *
    2966             :  * For analyze, the analysis done is that the number of tuples inserted,
    2967             :  * deleted and updated since the last analyze exceeds a threshold calculated
    2968             :  * in the same fashion as above.  Note that the cumulative stats system stores
    2969             :  * the number of tuples (both live and dead) that there were as of the last
    2970             :  * analyze.  This is asymmetric to the VACUUM case.
    2971             :  *
    2972             :  * We also force vacuum if the table's relfrozenxid is more than freeze_max_age
    2973             :  * transactions back, and if its relminmxid is more than
    2974             :  * multixact_freeze_max_age multixacts back.
    2975             :  *
    2976             :  * A table whose autovacuum_enabled option is false is
    2977             :  * automatically skipped (unless we have to vacuum it due to freeze_max_age).
    2978             :  * Thus autovacuum can be disabled for specific tables. Also, when the cumulative
    2979             :  * stats system does not have data about a table, it will be skipped.
    2980             :  *
    2981             :  * A table whose vac_base_thresh value is < 0 takes the base value from the
    2982             :  * autovacuum_vacuum_threshold GUC variable.  Similarly, a vac_scale_factor
    2983             :  * value < 0 is substituted with the value of
    2984             :  * autovacuum_vacuum_scale_factor GUC variable.  Ditto for analyze.
    2985             :  */
    2986             : static void
    2987      783174 : relation_needs_vacanalyze(Oid relid,
    2988             :                           AutoVacOpts *relopts,
    2989             :                           Form_pg_class classForm,
    2990             :                           PgStat_StatTabEntry *tabentry,
    2991             :                           int effective_multixact_freeze_max_age,
    2992             :  /* output params below */
    2993             :                           bool *dovacuum,
    2994             :                           bool *doanalyze,
    2995             :                           bool *wraparound)
    2996             : {
    2997             :     bool        force_vacuum;
    2998             :     bool        av_enabled;
    2999             : 
    3000             :     /* constants from reloptions or GUC variables */
    3001             :     int         vac_base_thresh,
    3002             :                 vac_max_thresh,
    3003             :                 vac_ins_base_thresh,
    3004             :                 anl_base_thresh;
    3005             :     float4      vac_scale_factor,
    3006             :                 vac_ins_scale_factor,
    3007             :                 anl_scale_factor;
    3008             : 
    3009             :     /* thresholds calculated from above constants */
    3010             :     float4      vacthresh,
    3011             :                 vacinsthresh,
    3012             :                 anlthresh;
    3013             : 
    3014             :     /* number of vacuum (resp. analyze) tuples at this time */
    3015             :     float4      vactuples,
    3016             :                 instuples,
    3017             :                 anltuples;
    3018             : 
    3019             :     /* freeze parameters */
    3020             :     int         freeze_max_age;
    3021             :     int         multixact_freeze_max_age;
    3022             :     TransactionId xidForceLimit;
    3023             :     TransactionId relfrozenxid;
    3024             :     MultiXactId multiForceLimit;
    3025             : 
    3026             :     Assert(classForm != NULL);
    3027             :     Assert(OidIsValid(relid));
    3028             : 
    3029             :     /*
    3030             :      * Determine vacuum/analyze equation parameters.  We have two possible
    3031             :      * sources: the passed reloptions (which could be a main table or a toast
    3032             :      * table), or the autovacuum GUC variables.
    3033             :      */
    3034             : 
    3035             :     /* -1 in autovac setting means use plain vacuum_scale_factor */
    3036       15360 :     vac_scale_factor = (relopts && relopts->vacuum_scale_factor >= 0)
    3037           0 :         ? relopts->vacuum_scale_factor
    3038      798534 :         : autovacuum_vac_scale;
    3039             : 
    3040       15360 :     vac_base_thresh = (relopts && relopts->vacuum_threshold >= 0)
    3041             :         ? relopts->vacuum_threshold
    3042      798534 :         : autovacuum_vac_thresh;
    3043             : 
    3044             :     /* -1 is used to disable max threshold */
    3045       15360 :     vac_max_thresh = (relopts && relopts->vacuum_max_threshold >= -1)
    3046             :         ? relopts->vacuum_max_threshold
    3047      798534 :         : autovacuum_vac_max_thresh;
    3048             : 
    3049       15360 :     vac_ins_scale_factor = (relopts && relopts->vacuum_ins_scale_factor >= 0)
    3050           0 :         ? relopts->vacuum_ins_scale_factor
    3051      798534 :         : autovacuum_vac_ins_scale;
    3052             : 
    3053             :     /* -1 is used to disable insert vacuums */
    3054       15360 :     vac_ins_base_thresh = (relopts && relopts->vacuum_ins_threshold >= -1)
    3055             :         ? relopts->vacuum_ins_threshold
    3056      798534 :         : autovacuum_vac_ins_thresh;
    3057             : 
    3058       15360 :     anl_scale_factor = (relopts && relopts->analyze_scale_factor >= 0)
    3059           0 :         ? relopts->analyze_scale_factor
    3060      798534 :         : autovacuum_anl_scale;
    3061             : 
    3062       15360 :     anl_base_thresh = (relopts && relopts->analyze_threshold >= 0)
    3063             :         ? relopts->analyze_threshold
    3064      798534 :         : autovacuum_anl_thresh;
    3065             : 
    3066       15360 :     freeze_max_age = (relopts && relopts->freeze_max_age >= 0)
    3067           0 :         ? Min(relopts->freeze_max_age, autovacuum_freeze_max_age)
    3068      798534 :         : autovacuum_freeze_max_age;
    3069             : 
    3070       15360 :     multixact_freeze_max_age = (relopts && relopts->multixact_freeze_max_age >= 0)
    3071           0 :         ? Min(relopts->multixact_freeze_max_age, effective_multixact_freeze_max_age)
    3072      798534 :         : effective_multixact_freeze_max_age;
    3073             : 
    3074      783174 :     av_enabled = (relopts ? relopts->enabled : true);
    3075             : 
    3076             :     /* Force vacuum if table is at risk of wraparound */
    3077      783174 :     xidForceLimit = recentXid - freeze_max_age;
    3078      783174 :     if (xidForceLimit < FirstNormalTransactionId)
    3079           0 :         xidForceLimit -= FirstNormalTransactionId;
    3080      783174 :     relfrozenxid = classForm->relfrozenxid;
    3081     1566348 :     force_vacuum = (TransactionIdIsNormal(relfrozenxid) &&
    3082      783174 :                     TransactionIdPrecedes(relfrozenxid, xidForceLimit));
    3083      783174 :     if (!force_vacuum)
    3084             :     {
    3085      259122 :         MultiXactId relminmxid = classForm->relminmxid;
    3086             : 
    3087      259122 :         multiForceLimit = recentMulti - multixact_freeze_max_age;
    3088      259122 :         if (multiForceLimit < FirstMultiXactId)
    3089           0 :             multiForceLimit -= FirstMultiXactId;
    3090      518244 :         force_vacuum = MultiXactIdIsValid(relminmxid) &&
    3091      259122 :             MultiXactIdPrecedes(relminmxid, multiForceLimit);
    3092             :     }
    3093      783174 :     *wraparound = force_vacuum;
    3094             : 
    3095             :     /* User disabled it in pg_class.reloptions?  (But ignore if at risk) */
    3096      783174 :     if (!av_enabled && !force_vacuum)
    3097             :     {
    3098        1788 :         *doanalyze = false;
    3099        1788 :         *dovacuum = false;
    3100        1788 :         return;
    3101             :     }
    3102             : 
    3103             :     /*
    3104             :      * If we found stats for the table, and autovacuum is currently enabled,
    3105             :      * make a threshold-based decision whether to vacuum and/or analyze.  If
    3106             :      * autovacuum is currently disabled, we must be here for anti-wraparound
    3107             :      * vacuuming only, so don't vacuum (or analyze) anything that's not being
    3108             :      * forced.
    3109             :      */
    3110      781386 :     if (PointerIsValid(tabentry) && AutoVacuumingActive())
    3111      771920 :     {
    3112      771920 :         float4      pcnt_unfrozen = 1;
    3113      771920 :         float4      reltuples = classForm->reltuples;
    3114      771920 :         int32       relpages = classForm->relpages;
    3115      771920 :         int32       relallfrozen = classForm->relallfrozen;
    3116             : 
    3117      771920 :         vactuples = tabentry->dead_tuples;
    3118      771920 :         instuples = tabentry->ins_since_vacuum;
    3119      771920 :         anltuples = tabentry->mod_since_analyze;
    3120             : 
    3121             :         /* If the table hasn't yet been vacuumed, take reltuples as zero */
    3122      771920 :         if (reltuples < 0)
    3123        3000 :             reltuples = 0;
    3124             : 
    3125             :         /*
    3126             :          * If we have data for relallfrozen, calculate the unfrozen percentage
    3127             :          * of the table to modify insert scale factor. This helps us decide
    3128             :          * whether or not to vacuum an insert-heavy table based on the number
    3129             :          * of inserts to the more "active" part of the table.
    3130             :          */
    3131      771920 :         if (relpages > 0 && relallfrozen > 0)
    3132             :         {
    3133             :             /*
    3134             :              * It could be the stats were updated manually and relallfrozen >
    3135             :              * relpages. Clamp relallfrozen to relpages to avoid nonsensical
    3136             :              * calculations.
    3137             :              */
    3138      299658 :             relallfrozen = Min(relallfrozen, relpages);
    3139      299658 :             pcnt_unfrozen = 1 - ((float4) relallfrozen / relpages);
    3140             :         }
    3141             : 
    3142      771920 :         vacthresh = (float4) vac_base_thresh + vac_scale_factor * reltuples;
    3143      771920 :         if (vac_max_thresh >= 0 && vacthresh > (float4) vac_max_thresh)
    3144           0 :             vacthresh = (float4) vac_max_thresh;
    3145             : 
    3146      771920 :         vacinsthresh = (float4) vac_ins_base_thresh +
    3147      771920 :             vac_ins_scale_factor * reltuples * pcnt_unfrozen;
    3148      771920 :         anlthresh = (float4) anl_base_thresh + anl_scale_factor * reltuples;
    3149             : 
    3150             :         /*
    3151             :          * Note that we don't need to take special consideration for stat
    3152             :          * reset, because if that happens, the last vacuum and analyze counts
    3153             :          * will be reset too.
    3154             :          */
    3155      771920 :         if (vac_ins_base_thresh >= 0)
    3156      771920 :             elog(DEBUG3, "%s: vac: %.0f (threshold %.0f), ins: %.0f (threshold %.0f), anl: %.0f (threshold %.0f)",
    3157             :                  NameStr(classForm->relname),
    3158             :                  vactuples, vacthresh, instuples, vacinsthresh, anltuples, anlthresh);
    3159             :         else
    3160           0 :             elog(DEBUG3, "%s: vac: %.0f (threshold %.0f), ins: (disabled), anl: %.0f (threshold %.0f)",
    3161             :                  NameStr(classForm->relname),
    3162             :                  vactuples, vacthresh, anltuples, anlthresh);
    3163             : 
    3164             :         /* Determine if this table needs vacuum or analyze. */
    3165     1021550 :         *dovacuum = force_vacuum || (vactuples > vacthresh) ||
    3166      249630 :             (vac_ins_base_thresh >= 0 && instuples > vacinsthresh);
    3167      771920 :         *doanalyze = (anltuples > anlthresh);
    3168             :     }
    3169             :     else
    3170             :     {
    3171             :         /*
    3172             :          * Skip a table not found in stat hash, unless we have to force vacuum
    3173             :          * for anti-wrap purposes.  If it's not acted upon, there's no need to
    3174             :          * vacuum it.
    3175             :          */
    3176        9466 :         *dovacuum = force_vacuum;
    3177        9466 :         *doanalyze = false;
    3178             :     }
    3179             : 
    3180             :     /* ANALYZE refuses to work with pg_statistic */
    3181      781386 :     if (relid == StatisticRelationId)
    3182        7132 :         *doanalyze = false;
    3183             : }
    3184             : 
    3185             : /*
    3186             :  * autovacuum_do_vac_analyze
    3187             :  *      Vacuum and/or analyze the specified table
    3188             :  *
    3189             :  * We expect the caller to have switched into a memory context that won't
    3190             :  * disappear at transaction commit.
    3191             :  */
    3192             : static void
    3193      262140 : autovacuum_do_vac_analyze(autovac_table *tab, BufferAccessStrategy bstrategy)
    3194             : {
    3195             :     RangeVar   *rangevar;
    3196             :     VacuumRelation *rel;
    3197             :     List       *rel_list;
    3198             :     MemoryContext vac_context;
    3199             :     MemoryContext old_context;
    3200             : 
    3201             :     /* Let pgstat know what we're doing */
    3202      262140 :     autovac_report_activity(tab);
    3203             : 
    3204             :     /* Create a context that vacuum() can use as cross-transaction storage */
    3205      262140 :     vac_context = AllocSetContextCreate(CurrentMemoryContext,
    3206             :                                         "Vacuum",
    3207             :                                         ALLOCSET_DEFAULT_SIZES);
    3208             : 
    3209             :     /* Set up one VacuumRelation target, identified by OID, for vacuum() */
    3210      262140 :     old_context = MemoryContextSwitchTo(vac_context);
    3211      262140 :     rangevar = makeRangeVar(tab->at_nspname, tab->at_relname, -1);
    3212      262140 :     rel = makeVacuumRelation(rangevar, tab->at_relid, NIL);
    3213      262140 :     rel_list = list_make1(rel);
    3214      262140 :     MemoryContextSwitchTo(old_context);
    3215             : 
    3216      262140 :     vacuum(rel_list, tab->at_params, bstrategy, vac_context, true);
    3217             : 
    3218      262140 :     MemoryContextDelete(vac_context);
    3219      262140 : }
    3220             : 
    3221             : /*
    3222             :  * autovac_report_activity
    3223             :  *      Report to pgstat what autovacuum is doing
    3224             :  *
    3225             :  * We send a SQL string corresponding to what the user would see if the
    3226             :  * equivalent command was to be issued manually.
    3227             :  *
    3228             :  * Note we assume that we are going to report the next command as soon as we're
    3229             :  * done with the current one, and exit right after the last one, so we don't
    3230             :  * bother to report "<IDLE>" or some such.
    3231             :  */
    3232             : static void
    3233      262140 : autovac_report_activity(autovac_table *tab)
    3234             : {
    3235             : #define MAX_AUTOVAC_ACTIV_LEN (NAMEDATALEN * 2 + 56)
    3236             :     char        activity[MAX_AUTOVAC_ACTIV_LEN];
    3237             :     int         len;
    3238             : 
    3239             :     /* Report the command and possible options */
    3240      262140 :     if (tab->at_params.options & VACOPT_VACUUM)
    3241      261784 :         snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
    3242             :                  "autovacuum: VACUUM%s",
    3243      261784 :                  tab->at_params.options & VACOPT_ANALYZE ? " ANALYZE" : "");
    3244             :     else
    3245         356 :         snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
    3246             :                  "autovacuum: ANALYZE");
    3247             : 
    3248             :     /*
    3249             :      * Report the qualified name of the relation.
    3250             :      */
    3251      262140 :     len = strlen(activity);
    3252             : 
    3253      262140 :     snprintf(activity + len, MAX_AUTOVAC_ACTIV_LEN - len,
    3254             :              " %s.%s%s", tab->at_nspname, tab->at_relname,
    3255      262140 :              tab->at_params.is_wraparound ? " (to prevent wraparound)" : "");
    3256             : 
    3257             :     /* Set statement_timestamp() to current time for pg_stat_activity */
    3258      262140 :     SetCurrentStatementStartTimestamp();
    3259             : 
    3260      262140 :     pgstat_report_activity(STATE_RUNNING, activity);
    3261      262140 : }
    3262             : 
    3263             : /*
    3264             :  * autovac_report_workitem
    3265             :  *      Report to pgstat that autovacuum is processing a work item
    3266             :  */
    3267             : static void
    3268           6 : autovac_report_workitem(AutoVacuumWorkItem *workitem,
    3269             :                         const char *nspname, const char *relname)
    3270             : {
    3271             :     char        activity[MAX_AUTOVAC_ACTIV_LEN + 12 + 2];
    3272             :     char        blk[12 + 2];
    3273             :     int         len;
    3274             : 
    3275           6 :     switch (workitem->avw_type)
    3276             :     {
    3277           6 :         case AVW_BRINSummarizeRange:
    3278           6 :             snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
    3279             :                      "autovacuum: BRIN summarize");
    3280           6 :             break;
    3281             :     }
    3282             : 
    3283             :     /*
    3284             :      * Report the qualified name of the relation, and the block number if any
    3285             :      */
    3286           6 :     len = strlen(activity);
    3287             : 
    3288           6 :     if (BlockNumberIsValid(workitem->avw_blockNumber))
    3289           6 :         snprintf(blk, sizeof(blk), " %u", workitem->avw_blockNumber);
    3290             :     else
    3291           0 :         blk[0] = '\0';
    3292             : 
    3293           6 :     snprintf(activity + len, MAX_AUTOVAC_ACTIV_LEN - len,
    3294             :              " %s.%s%s", nspname, relname, blk);
    3295             : 
    3296             :     /* Set statement_timestamp() to current time for pg_stat_activity */
    3297           6 :     SetCurrentStatementStartTimestamp();
    3298             : 
    3299           6 :     pgstat_report_activity(STATE_RUNNING, activity);
    3300           6 : }
    3301             : 
    3302             : /*
    3303             :  * AutoVacuumingActive
    3304             :  *      Check GUC vars and report whether the autovacuum process should be
    3305             :  *      running.
    3306             :  */
    3307             : bool
    3308      846450 : AutoVacuumingActive(void)
    3309             : {
    3310      846450 :     if (!autovacuum_start_daemon || !pgstat_track_counts)
    3311        9804 :         return false;
    3312      836646 :     return true;
    3313             : }
    3314             : 
    3315             : /*
    3316             :  * Request one work item to the next autovacuum run processing our database.
    3317             :  * Return false if the request can't be recorded.
    3318             :  */
    3319             : bool
    3320           6 : AutoVacuumRequestWork(AutoVacuumWorkItemType type, Oid relationId,
    3321             :                       BlockNumber blkno)
    3322             : {
    3323             :     int         i;
    3324           6 :     bool        result = false;
    3325             : 
    3326           6 :     LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    3327             : 
    3328             :     /*
    3329             :      * Locate an unused work item and fill it with the given data.
    3330             :      */
    3331          12 :     for (i = 0; i < NUM_WORKITEMS; i++)
    3332             :     {
    3333          12 :         AutoVacuumWorkItem *workitem = &AutoVacuumShmem->av_workItems[i];
    3334             : 
    3335          12 :         if (workitem->avw_used)
    3336           6 :             continue;
    3337             : 
    3338           6 :         workitem->avw_used = true;
    3339           6 :         workitem->avw_active = false;
    3340           6 :         workitem->avw_type = type;
    3341           6 :         workitem->avw_database = MyDatabaseId;
    3342           6 :         workitem->avw_relation = relationId;
    3343           6 :         workitem->avw_blockNumber = blkno;
    3344           6 :         result = true;
    3345             : 
    3346             :         /* done */
    3347           6 :         break;
    3348             :     }
    3349             : 
    3350           6 :     LWLockRelease(AutovacuumLock);
    3351             : 
    3352           6 :     return result;
    3353             : }
    3354             : 
    3355             : /*
    3356             :  * autovac_init
    3357             :  *      This is called at postmaster initialization.
    3358             :  *
    3359             :  * All we do here is annoy the user if he got it wrong.
    3360             :  */
    3361             : void
    3362        1704 : autovac_init(void)
    3363             : {
    3364        1704 :     if (!autovacuum_start_daemon)
    3365         242 :         return;
    3366        1462 :     else if (!pgstat_track_counts)
    3367           0 :         ereport(WARNING,
    3368             :                 (errmsg("autovacuum not started because of misconfiguration"),
    3369             :                  errhint("Enable the \"track_counts\" option.")));
    3370             :     else
    3371        1462 :         check_av_worker_gucs();
    3372             : }
    3373             : 
    3374             : /*
    3375             :  * AutoVacuumShmemSize
    3376             :  *      Compute space needed for autovacuum-related shared memory
    3377             :  */
    3378             : Size
    3379        6156 : AutoVacuumShmemSize(void)
    3380             : {
    3381             :     Size        size;
    3382             : 
    3383             :     /*
    3384             :      * Need the fixed struct and the array of WorkerInfoData.
    3385             :      */
    3386        6156 :     size = sizeof(AutoVacuumShmemStruct);
    3387        6156 :     size = MAXALIGN(size);
    3388        6156 :     size = add_size(size, mul_size(autovacuum_worker_slots,
    3389             :                                    sizeof(WorkerInfoData)));
    3390        6156 :     return size;
    3391             : }
    3392             : 
    3393             : /*
    3394             :  * AutoVacuumShmemInit
    3395             :  *      Allocate and initialize autovacuum-related shared memory
    3396             :  */
    3397             : void
    3398        2152 : AutoVacuumShmemInit(void)
    3399             : {
    3400             :     bool        found;
    3401             : 
    3402        2152 :     AutoVacuumShmem = (AutoVacuumShmemStruct *)
    3403        2152 :         ShmemInitStruct("AutoVacuum Data",
    3404             :                         AutoVacuumShmemSize(),
    3405             :                         &found);
    3406             : 
    3407        2152 :     if (!IsUnderPostmaster)
    3408             :     {
    3409             :         WorkerInfo  worker;
    3410             :         int         i;
    3411             : 
    3412             :         Assert(!found);
    3413             : 
    3414        2152 :         AutoVacuumShmem->av_launcherpid = 0;
    3415        2152 :         dclist_init(&AutoVacuumShmem->av_freeWorkers);
    3416        2152 :         dlist_init(&AutoVacuumShmem->av_runningWorkers);
    3417        2152 :         AutoVacuumShmem->av_startingWorker = NULL;
    3418        2152 :         memset(AutoVacuumShmem->av_workItems, 0,
    3419             :                sizeof(AutoVacuumWorkItem) * NUM_WORKITEMS);
    3420             : 
    3421        2152 :         worker = (WorkerInfo) ((char *) AutoVacuumShmem +
    3422             :                                MAXALIGN(sizeof(AutoVacuumShmemStruct)));
    3423             : 
    3424             :         /* initialize the WorkerInfo free list */
    3425       25612 :         for (i = 0; i < autovacuum_worker_slots; i++)
    3426             :         {
    3427       23460 :             dclist_push_head(&AutoVacuumShmem->av_freeWorkers,
    3428       23460 :                              &worker[i].wi_links);
    3429       23460 :             pg_atomic_init_flag(&worker[i].wi_dobalance);
    3430             :         }
    3431             : 
    3432        2152 :         pg_atomic_init_u32(&AutoVacuumShmem->av_nworkersForBalance, 0);
    3433             : 
    3434             :     }
    3435             :     else
    3436             :         Assert(found);
    3437        2152 : }
    3438             : 
    3439             : /*
    3440             :  * GUC check_hook for autovacuum_work_mem
    3441             :  */
    3442             : bool
    3443        2232 : check_autovacuum_work_mem(int *newval, void **extra, GucSource source)
    3444             : {
    3445             :     /*
    3446             :      * -1 indicates fallback.
    3447             :      *
    3448             :      * If we haven't yet changed the boot_val default of -1, just let it be.
    3449             :      * Autovacuum will look to maintenance_work_mem instead.
    3450             :      */
    3451        2232 :     if (*newval == -1)
    3452        2228 :         return true;
    3453             : 
    3454             :     /*
    3455             :      * We clamp manually-set values to at least 64kB.  Since
    3456             :      * maintenance_work_mem is always set to at least this value, do the same
    3457             :      * here.
    3458             :      */
    3459           4 :     if (*newval < 64)
    3460           4 :         *newval = 64;
    3461             : 
    3462           4 :     return true;
    3463             : }
    3464             : 
    3465             : /*
    3466             :  * Returns whether there is a free autovacuum worker slot available.
    3467             :  */
    3468             : static bool
    3469       37210 : av_worker_available(void)
    3470             : {
    3471             :     int         free_slots;
    3472             :     int         reserved_slots;
    3473             : 
    3474       37210 :     free_slots = dclist_count(&AutoVacuumShmem->av_freeWorkers);
    3475             : 
    3476       37210 :     reserved_slots = autovacuum_worker_slots - autovacuum_max_workers;
    3477       37210 :     reserved_slots = Max(0, reserved_slots);
    3478             : 
    3479       37210 :     return free_slots > reserved_slots;
    3480             : }
    3481             : 
    3482             : /*
    3483             :  * Emits a WARNING if autovacuum_worker_slots < autovacuum_max_workers.
    3484             :  */
    3485             : static void
    3486        1462 : check_av_worker_gucs(void)
    3487             : {
    3488        1462 :     if (autovacuum_worker_slots < autovacuum_max_workers)
    3489           0 :         ereport(WARNING,
    3490             :                 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
    3491             :                  errmsg("\"autovacuum_max_workers\" (%d) should be less than or equal to \"autovacuum_worker_slots\" (%d)",
    3492             :                         autovacuum_max_workers, autovacuum_worker_slots),
    3493             :                  errdetail("The server will only start up to \"autovacuum_worker_slots\" (%d) autovacuum workers at a given time.",
    3494             :                            autovacuum_worker_slots)));
    3495        1462 : }

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