LCOV - code coverage report
Current view: top level - src/backend/postmaster - autovacuum.c (source / functions) Hit Total Coverage
Test: PostgreSQL 17devel Lines: 760 953 79.7 %
Date: 2023-12-05 09:10:49 Functions: 34 35 97.1 %
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) 1996-2023, 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 "commands/dbcommands.h"
      80             : #include "commands/vacuum.h"
      81             : #include "lib/ilist.h"
      82             : #include "libpq/pqsignal.h"
      83             : #include "miscadmin.h"
      84             : #include "nodes/makefuncs.h"
      85             : #include "pgstat.h"
      86             : #include "postmaster/autovacuum.h"
      87             : #include "postmaster/fork_process.h"
      88             : #include "postmaster/interrupt.h"
      89             : #include "postmaster/postmaster.h"
      90             : #include "storage/bufmgr.h"
      91             : #include "storage/ipc.h"
      92             : #include "storage/latch.h"
      93             : #include "storage/lmgr.h"
      94             : #include "storage/pmsignal.h"
      95             : #include "storage/proc.h"
      96             : #include "storage/procsignal.h"
      97             : #include "storage/sinvaladt.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/lsyscache.h"
     104             : #include "utils/memutils.h"
     105             : #include "utils/ps_status.h"
     106             : #include "utils/rel.h"
     107             : #include "utils/snapmgr.h"
     108             : #include "utils/syscache.h"
     109             : #include "utils/timeout.h"
     110             : #include "utils/timestamp.h"
     111             : 
     112             : 
     113             : /*
     114             :  * GUC parameters
     115             :  */
     116             : bool        autovacuum_start_daemon = false;
     117             : int         autovacuum_max_workers;
     118             : int         autovacuum_work_mem = -1;
     119             : int         autovacuum_naptime;
     120             : int         autovacuum_vac_thresh;
     121             : double      autovacuum_vac_scale;
     122             : int         autovacuum_vac_ins_thresh;
     123             : double      autovacuum_vac_ins_scale;
     124             : int         autovacuum_anl_thresh;
     125             : double      autovacuum_anl_scale;
     126             : int         autovacuum_freeze_max_age;
     127             : int         autovacuum_multixact_freeze_max_age;
     128             : 
     129             : double      autovacuum_vac_cost_delay;
     130             : int         autovacuum_vac_cost_limit;
     131             : 
     132             : int         Log_autovacuum_min_duration = 600000;
     133             : 
     134             : /* the minimum allowed time between two awakenings of the launcher */
     135             : #define MIN_AUTOVAC_SLEEPTIME 100.0 /* milliseconds */
     136             : #define MAX_AUTOVAC_SLEEPTIME 300   /* seconds */
     137             : 
     138             : /* Flags to tell if we are in an autovacuum process */
     139             : static bool am_autovacuum_launcher = false;
     140             : static bool am_autovacuum_worker = false;
     141             : 
     142             : /*
     143             :  * Variables to save the cost-related storage parameters for the current
     144             :  * relation being vacuumed by this autovacuum worker. Using these, we can
     145             :  * ensure we don't overwrite the values of vacuum_cost_delay and
     146             :  * vacuum_cost_limit after reloading the configuration file. They are
     147             :  * initialized to "invalid" values to indicate that no cost-related storage
     148             :  * parameters were specified and will be set in do_autovacuum() after checking
     149             :  * the storage parameters in table_recheck_autovac().
     150             :  */
     151             : static double av_storage_param_cost_delay = -1;
     152             : static int  av_storage_param_cost_limit = -1;
     153             : 
     154             : /* Flags set by signal handlers */
     155             : static volatile sig_atomic_t got_SIGUSR2 = false;
     156             : 
     157             : /* Comparison points for determining whether freeze_max_age is exceeded */
     158             : static TransactionId recentXid;
     159             : static MultiXactId recentMulti;
     160             : 
     161             : /* Default freeze ages to use for autovacuum (varies by database) */
     162             : static int  default_freeze_min_age;
     163             : static int  default_freeze_table_age;
     164             : static int  default_multixact_freeze_min_age;
     165             : static int  default_multixact_freeze_table_age;
     166             : 
     167             : /* Memory context for long-lived data */
     168             : static MemoryContext AutovacMemCxt;
     169             : 
     170             : /* struct to keep track of databases in launcher */
     171             : typedef struct avl_dbase
     172             : {
     173             :     Oid         adl_datid;      /* hash key -- must be first */
     174             :     TimestampTz adl_next_worker;
     175             :     int         adl_score;
     176             :     dlist_node  adl_node;
     177             : } avl_dbase;
     178             : 
     179             : /* struct to keep track of databases in worker */
     180             : typedef struct avw_dbase
     181             : {
     182             :     Oid         adw_datid;
     183             :     char       *adw_name;
     184             :     TransactionId adw_frozenxid;
     185             :     MultiXactId adw_minmulti;
     186             :     PgStat_StatDBEntry *adw_entry;
     187             : } avw_dbase;
     188             : 
     189             : /* struct to keep track of tables to vacuum and/or analyze, in 1st pass */
     190             : typedef struct av_relation
     191             : {
     192             :     Oid         ar_toastrelid;  /* hash key - must be first */
     193             :     Oid         ar_relid;
     194             :     bool        ar_hasrelopts;
     195             :     AutoVacOpts ar_reloptions;  /* copy of AutoVacOpts from the main table's
     196             :                                  * reloptions, or NULL if none */
     197             : } av_relation;
     198             : 
     199             : /* struct to keep track of tables to vacuum and/or analyze, after rechecking */
     200             : typedef struct autovac_table
     201             : {
     202             :     Oid         at_relid;
     203             :     VacuumParams at_params;
     204             :     double      at_storage_param_vac_cost_delay;
     205             :     int         at_storage_param_vac_cost_limit;
     206             :     bool        at_dobalance;
     207             :     bool        at_sharedrel;
     208             :     char       *at_relname;
     209             :     char       *at_nspname;
     210             :     char       *at_datname;
     211             : } autovac_table;
     212             : 
     213             : /*-------------
     214             :  * This struct holds information about a single worker's whereabouts.  We keep
     215             :  * an array of these in shared memory, sized according to
     216             :  * autovacuum_max_workers.
     217             :  *
     218             :  * wi_links     entry into free list or running list
     219             :  * wi_dboid     OID of the database this worker is supposed to work on
     220             :  * wi_tableoid  OID of the table currently being vacuumed, if any
     221             :  * wi_sharedrel flag indicating whether table is marked relisshared
     222             :  * wi_proc      pointer to PGPROC of the running worker, NULL if not started
     223             :  * wi_launchtime Time at which this worker was launched
     224             :  * wi_dobalance Whether this worker should be included in balance calculations
     225             :  *
     226             :  * All fields are protected by AutovacuumLock, except for wi_tableoid and
     227             :  * wi_sharedrel which are protected by AutovacuumScheduleLock (note these
     228             :  * two fields are read-only for everyone except that worker itself).
     229             :  *-------------
     230             :  */
     231             : typedef struct WorkerInfoData
     232             : {
     233             :     dlist_node  wi_links;
     234             :     Oid         wi_dboid;
     235             :     Oid         wi_tableoid;
     236             :     PGPROC     *wi_proc;
     237             :     TimestampTz wi_launchtime;
     238             :     pg_atomic_flag wi_dobalance;
     239             :     bool        wi_sharedrel;
     240             : } WorkerInfoData;
     241             : 
     242             : typedef struct WorkerInfoData *WorkerInfo;
     243             : 
     244             : /*
     245             :  * Possible signals received by the launcher from remote processes.  These are
     246             :  * stored atomically in shared memory so that other processes can set them
     247             :  * without locking.
     248             :  */
     249             : typedef enum
     250             : {
     251             :     AutoVacForkFailed,          /* failed trying to start a worker */
     252             :     AutoVacRebalance,           /* rebalance the cost limits */
     253             :     AutoVacNumSignals,          /* must be last */
     254             : }           AutoVacuumSignal;
     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             :     dlist_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             : /* Pointer to my own WorkerInfo, valid on each worker */
     313             : static WorkerInfo MyWorkerInfo = NULL;
     314             : 
     315             : /* PID of launcher, valid only in worker while shutting down */
     316             : int         AutovacuumLauncherPid = 0;
     317             : 
     318             : #ifdef EXEC_BACKEND
     319             : static pid_t avlauncher_forkexec(void);
     320             : static pid_t avworker_forkexec(void);
     321             : #endif
     322             : NON_EXEC_STATIC void AutoVacWorkerMain(int argc, char *argv[]) pg_attribute_noreturn();
     323             : NON_EXEC_STATIC void AutoVacLauncherMain(int argc, char *argv[]) pg_attribute_noreturn();
     324             : 
     325             : static Oid  do_start_worker(void);
     326             : static void HandleAutoVacLauncherInterrupts(void);
     327             : static void AutoVacLauncherShutdown(void) pg_attribute_noreturn();
     328             : static void launcher_determine_sleep(bool canlaunch, bool recursing,
     329             :                                      struct timeval *nap);
     330             : static void launch_worker(TimestampTz now);
     331             : static List *get_database_list(void);
     332             : static void rebuild_database_list(Oid newdb);
     333             : static int  db_comparator(const void *a, const void *b);
     334             : static void autovac_recalculate_workers_for_balance(void);
     335             : 
     336             : static void do_autovacuum(void);
     337             : static void FreeWorkerInfo(int code, Datum arg);
     338             : 
     339             : static autovac_table *table_recheck_autovac(Oid relid, HTAB *table_toast_map,
     340             :                                             TupleDesc pg_class_desc,
     341             :                                             int effective_multixact_freeze_max_age);
     342             : static void recheck_relation_needs_vacanalyze(Oid relid, AutoVacOpts *avopts,
     343             :                                               Form_pg_class classForm,
     344             :                                               int effective_multixact_freeze_max_age,
     345             :                                               bool *dovacuum, bool *doanalyze, bool *wraparound);
     346             : static void relation_needs_vacanalyze(Oid relid, AutoVacOpts *relopts,
     347             :                                       Form_pg_class classForm,
     348             :                                       PgStat_StatTabEntry *tabentry,
     349             :                                       int effective_multixact_freeze_max_age,
     350             :                                       bool *dovacuum, bool *doanalyze, bool *wraparound);
     351             : 
     352             : static void autovacuum_do_vac_analyze(autovac_table *tab,
     353             :                                       BufferAccessStrategy bstrategy);
     354             : static AutoVacOpts *extract_autovac_opts(HeapTuple tup,
     355             :                                          TupleDesc pg_class_desc);
     356             : static void perform_work_item(AutoVacuumWorkItem *workitem);
     357             : static void autovac_report_activity(autovac_table *tab);
     358             : static void autovac_report_workitem(AutoVacuumWorkItem *workitem,
     359             :                                     const char *nspname, const char *relname);
     360             : static void avl_sigusr2_handler(SIGNAL_ARGS);
     361             : 
     362             : 
     363             : 
     364             : /********************************************************************
     365             :  *                    AUTOVACUUM LAUNCHER CODE
     366             :  ********************************************************************/
     367             : 
     368             : #ifdef EXEC_BACKEND
     369             : /*
     370             :  * forkexec routine for the autovacuum launcher process.
     371             :  *
     372             :  * Format up the arglist, then fork and exec.
     373             :  */
     374             : static pid_t
     375             : avlauncher_forkexec(void)
     376             : {
     377             :     char       *av[10];
     378             :     int         ac = 0;
     379             : 
     380             :     av[ac++] = "postgres";
     381             :     av[ac++] = "--forkavlauncher";
     382             :     av[ac++] = NULL;            /* filled in by postmaster_forkexec */
     383             :     av[ac] = NULL;
     384             : 
     385             :     Assert(ac < lengthof(av));
     386             : 
     387             :     return postmaster_forkexec(ac, av);
     388             : }
     389             : #endif
     390             : 
     391             : /*
     392             :  * Main entry point for autovacuum launcher process, to be called from the
     393             :  * postmaster.
     394             :  */
     395             : int
     396        1004 : StartAutoVacLauncher(void)
     397             : {
     398             :     pid_t       AutoVacPID;
     399             : 
     400             : #ifdef EXEC_BACKEND
     401             :     switch ((AutoVacPID = avlauncher_forkexec()))
     402             : #else
     403        1004 :     switch ((AutoVacPID = fork_process()))
     404             : #endif
     405             :     {
     406           0 :         case -1:
     407           0 :             ereport(LOG,
     408             :                     (errmsg("could not fork autovacuum launcher process: %m")));
     409           0 :             return 0;
     410             : 
     411             : #ifndef EXEC_BACKEND
     412         614 :         case 0:
     413             :             /* in postmaster child ... */
     414         614 :             InitPostmasterChild();
     415             : 
     416             :             /* Close the postmaster's sockets */
     417         614 :             ClosePostmasterPorts(false);
     418             : 
     419         614 :             AutoVacLauncherMain(0, NULL);
     420             :             break;
     421             : #endif
     422        1004 :         default:
     423        1004 :             return (int) AutoVacPID;
     424             :     }
     425             : 
     426             :     /* shouldn't get here */
     427             :     return 0;
     428             : }
     429             : 
     430             : /*
     431             :  * Main loop for the autovacuum launcher process.
     432             :  */
     433             : NON_EXEC_STATIC void
     434         614 : AutoVacLauncherMain(int argc, char *argv[])
     435             : {
     436             :     sigjmp_buf  local_sigjmp_buf;
     437             : 
     438         614 :     am_autovacuum_launcher = true;
     439             : 
     440         614 :     MyBackendType = B_AUTOVAC_LAUNCHER;
     441         614 :     init_ps_display(NULL);
     442             : 
     443         614 :     ereport(DEBUG1,
     444             :             (errmsg_internal("autovacuum launcher started")));
     445             : 
     446         614 :     if (PostAuthDelay)
     447           0 :         pg_usleep(PostAuthDelay * 1000000L);
     448             : 
     449         614 :     SetProcessingMode(InitProcessing);
     450             : 
     451             :     /*
     452             :      * Set up signal handlers.  We operate on databases much like a regular
     453             :      * backend, so we use the same signal handling.  See equivalent code in
     454             :      * tcop/postgres.c.
     455             :      */
     456         614 :     pqsignal(SIGHUP, SignalHandlerForConfigReload);
     457         614 :     pqsignal(SIGINT, StatementCancelHandler);
     458         614 :     pqsignal(SIGTERM, SignalHandlerForShutdownRequest);
     459             :     /* SIGQUIT handler was already set up by InitPostmasterChild */
     460             : 
     461         614 :     InitializeTimeouts();       /* establishes SIGALRM handler */
     462             : 
     463         614 :     pqsignal(SIGPIPE, SIG_IGN);
     464         614 :     pqsignal(SIGUSR1, procsignal_sigusr1_handler);
     465         614 :     pqsignal(SIGUSR2, avl_sigusr2_handler);
     466         614 :     pqsignal(SIGFPE, FloatExceptionHandler);
     467         614 :     pqsignal(SIGCHLD, SIG_DFL);
     468             : 
     469             :     /*
     470             :      * Create a per-backend PGPROC struct in shared memory.  We must do this
     471             :      * before we can use LWLocks or access any shared memory.
     472             :      */
     473         614 :     InitProcess();
     474             : 
     475             :     /* Early initialization */
     476         614 :     BaseInit();
     477             : 
     478         614 :     InitPostgres(NULL, InvalidOid, NULL, InvalidOid, 0, NULL);
     479             : 
     480         614 :     SetProcessingMode(NormalProcessing);
     481             : 
     482             :     /*
     483             :      * Create a memory context that we will do all our work in.  We do this so
     484             :      * that we can reset the context during error recovery and thereby avoid
     485             :      * possible memory leaks.
     486             :      */
     487         614 :     AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,
     488             :                                           "Autovacuum Launcher",
     489             :                                           ALLOCSET_DEFAULT_SIZES);
     490         614 :     MemoryContextSwitchTo(AutovacMemCxt);
     491             : 
     492             :     /*
     493             :      * If an exception is encountered, processing resumes here.
     494             :      *
     495             :      * This code is a stripped down version of PostgresMain error recovery.
     496             :      *
     497             :      * Note that we use sigsetjmp(..., 1), so that the prevailing signal mask
     498             :      * (to wit, BlockSig) will be restored when longjmp'ing to here.  Thus,
     499             :      * signals other than SIGQUIT will be blocked until we complete error
     500             :      * recovery.  It might seem that this policy makes the HOLD_INTERRUPTS()
     501             :      * call redundant, but it is not since InterruptPending might be set
     502             :      * already.
     503             :      */
     504         614 :     if (sigsetjmp(local_sigjmp_buf, 1) != 0)
     505             :     {
     506             :         /* since not using PG_TRY, must reset error stack by hand */
     507           0 :         error_context_stack = NULL;
     508             : 
     509             :         /* Prevents interrupts while cleaning up */
     510           0 :         HOLD_INTERRUPTS();
     511             : 
     512             :         /* Forget any pending QueryCancel or timeout request */
     513           0 :         disable_all_timeouts(false);
     514           0 :         QueryCancelPending = false; /* second to avoid race condition */
     515             : 
     516             :         /* Report the error to the server log */
     517           0 :         EmitErrorReport();
     518             : 
     519             :         /* Abort the current transaction in order to recover */
     520           0 :         AbortCurrentTransaction();
     521             : 
     522             :         /*
     523             :          * Release any other resources, for the case where we were not in a
     524             :          * transaction.
     525             :          */
     526           0 :         LWLockReleaseAll();
     527           0 :         pgstat_report_wait_end();
     528           0 :         UnlockBuffers();
     529             :         /* this is probably dead code, but let's be safe: */
     530           0 :         if (AuxProcessResourceOwner)
     531           0 :             ReleaseAuxProcessResources(false);
     532           0 :         AtEOXact_Buffers(false);
     533           0 :         AtEOXact_SMgr();
     534           0 :         AtEOXact_Files(false);
     535           0 :         AtEOXact_HashTables(false);
     536             : 
     537             :         /*
     538             :          * Now return to normal top-level context and clear ErrorContext for
     539             :          * next time.
     540             :          */
     541           0 :         MemoryContextSwitchTo(AutovacMemCxt);
     542           0 :         FlushErrorState();
     543             : 
     544             :         /* Flush any leaked data in the top-level context */
     545           0 :         MemoryContextReset(AutovacMemCxt);
     546             : 
     547             :         /* don't leave dangling pointers to freed memory */
     548           0 :         DatabaseListCxt = NULL;
     549           0 :         dlist_init(&DatabaseList);
     550             : 
     551             :         /* Now we can allow interrupts again */
     552           0 :         RESUME_INTERRUPTS();
     553             : 
     554             :         /* if in shutdown mode, no need for anything further; just go away */
     555           0 :         if (ShutdownRequestPending)
     556           0 :             AutoVacLauncherShutdown();
     557             : 
     558             :         /*
     559             :          * Sleep at least 1 second after any error.  We don't want to be
     560             :          * filling the error logs as fast as we can.
     561             :          */
     562           0 :         pg_usleep(1000000L);
     563             :     }
     564             : 
     565             :     /* We can now handle ereport(ERROR) */
     566         614 :     PG_exception_stack = &local_sigjmp_buf;
     567             : 
     568             :     /* must unblock signals before calling rebuild_database_list */
     569         614 :     sigprocmask(SIG_SETMASK, &UnBlockSig, NULL);
     570             : 
     571             :     /*
     572             :      * Set always-secure search path.  Launcher doesn't connect to a database,
     573             :      * so this has no effect.
     574             :      */
     575         614 :     SetConfigOption("search_path", "", PGC_SUSET, PGC_S_OVERRIDE);
     576             : 
     577             :     /*
     578             :      * Force zero_damaged_pages OFF in the autovac process, even if it is set
     579             :      * in postgresql.conf.  We don't really want such a dangerous option being
     580             :      * applied non-interactively.
     581             :      */
     582         614 :     SetConfigOption("zero_damaged_pages", "false", PGC_SUSET, PGC_S_OVERRIDE);
     583             : 
     584             :     /*
     585             :      * Force settable timeouts off to avoid letting these settings prevent
     586             :      * regular maintenance from being executed.
     587             :      */
     588         614 :     SetConfigOption("statement_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
     589         614 :     SetConfigOption("lock_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
     590         614 :     SetConfigOption("idle_in_transaction_session_timeout", "0",
     591             :                     PGC_SUSET, PGC_S_OVERRIDE);
     592             : 
     593             :     /*
     594             :      * Force default_transaction_isolation to READ COMMITTED.  We don't want
     595             :      * to pay the overhead of serializable mode, nor add any risk of causing
     596             :      * deadlocks or delaying other transactions.
     597             :      */
     598         614 :     SetConfigOption("default_transaction_isolation", "read committed",
     599             :                     PGC_SUSET, PGC_S_OVERRIDE);
     600             : 
     601             :     /*
     602             :      * Even when system is configured to use a different fetch consistency,
     603             :      * for autovac we always want fresh stats.
     604             :      */
     605         614 :     SetConfigOption("stats_fetch_consistency", "none", PGC_SUSET, PGC_S_OVERRIDE);
     606             : 
     607             :     /*
     608             :      * In emergency mode, just start a worker (unless shutdown was requested)
     609             :      * and go away.
     610             :      */
     611         614 :     if (!AutoVacuumingActive())
     612             :     {
     613           0 :         if (!ShutdownRequestPending)
     614           0 :             do_start_worker();
     615           0 :         proc_exit(0);           /* done */
     616             :     }
     617             : 
     618         614 :     AutoVacuumShmem->av_launcherpid = MyProcPid;
     619             : 
     620             :     /*
     621             :      * Create the initial database list.  The invariant we want this list to
     622             :      * keep is that it's ordered by decreasing next_time.  As soon as an entry
     623             :      * is updated to a higher time, it will be moved to the front (which is
     624             :      * correct because the only operation is to add autovacuum_naptime to the
     625             :      * entry, and time always increases).
     626             :      */
     627         614 :     rebuild_database_list(InvalidOid);
     628             : 
     629             :     /* loop until shutdown request */
     630        3214 :     while (!ShutdownRequestPending)
     631             :     {
     632             :         struct timeval nap;
     633        3214 :         TimestampTz current_time = 0;
     634             :         bool        can_launch;
     635             : 
     636             :         /*
     637             :          * This loop is a bit different from the normal use of WaitLatch,
     638             :          * because we'd like to sleep before the first launch of a child
     639             :          * process.  So it's WaitLatch, then ResetLatch, then check for
     640             :          * wakening conditions.
     641             :          */
     642             : 
     643        3214 :         launcher_determine_sleep(!dlist_is_empty(&AutoVacuumShmem->av_freeWorkers),
     644        3214 :                                  false, &nap);
     645             : 
     646             :         /*
     647             :          * Wait until naptime expires or we get some type of signal (all the
     648             :          * signal handlers will wake us by calling SetLatch).
     649             :          */
     650        3214 :         (void) WaitLatch(MyLatch,
     651             :                          WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
     652        3214 :                          (nap.tv_sec * 1000L) + (nap.tv_usec / 1000L),
     653             :                          WAIT_EVENT_AUTOVACUUM_MAIN);
     654             : 
     655        3208 :         ResetLatch(MyLatch);
     656             : 
     657        3208 :         HandleAutoVacLauncherInterrupts();
     658             : 
     659             :         /*
     660             :          * a worker finished, or postmaster signaled failure to start a worker
     661             :          */
     662        2600 :         if (got_SIGUSR2)
     663             :         {
     664          32 :             got_SIGUSR2 = false;
     665             : 
     666             :             /* rebalance cost limits, if needed */
     667          32 :             if (AutoVacuumShmem->av_signal[AutoVacRebalance])
     668             :             {
     669          16 :                 LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
     670          16 :                 AutoVacuumShmem->av_signal[AutoVacRebalance] = false;
     671          16 :                 autovac_recalculate_workers_for_balance();
     672          16 :                 LWLockRelease(AutovacuumLock);
     673             :             }
     674             : 
     675          32 :             if (AutoVacuumShmem->av_signal[AutoVacForkFailed])
     676             :             {
     677             :                 /*
     678             :                  * If the postmaster failed to start a new worker, we sleep
     679             :                  * for a little while and resend the signal.  The new worker's
     680             :                  * state is still in memory, so this is sufficient.  After
     681             :                  * that, we restart the main loop.
     682             :                  *
     683             :                  * XXX should we put a limit to the number of times we retry?
     684             :                  * I don't think it makes much sense, because a future start
     685             :                  * of a worker will continue to fail in the same way.
     686             :                  */
     687           0 :                 AutoVacuumShmem->av_signal[AutoVacForkFailed] = false;
     688           0 :                 pg_usleep(1000000L);    /* 1s */
     689           0 :                 SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER);
     690           0 :                 continue;
     691             :             }
     692             :         }
     693             : 
     694             :         /*
     695             :          * There are some conditions that we need to check before trying to
     696             :          * start a worker.  First, we need to make sure that there is a worker
     697             :          * slot available.  Second, we need to make sure that no other worker
     698             :          * failed while starting up.
     699             :          */
     700             : 
     701        2600 :         current_time = GetCurrentTimestamp();
     702        2600 :         LWLockAcquire(AutovacuumLock, LW_SHARED);
     703             : 
     704        2600 :         can_launch = !dlist_is_empty(&AutoVacuumShmem->av_freeWorkers);
     705             : 
     706        2600 :         if (AutoVacuumShmem->av_startingWorker != NULL)
     707             :         {
     708             :             int         waittime;
     709           0 :             WorkerInfo  worker = AutoVacuumShmem->av_startingWorker;
     710             : 
     711             :             /*
     712             :              * We can't launch another worker when another one is still
     713             :              * starting up (or failed while doing so), so just sleep for a bit
     714             :              * more; that worker will wake us up again as soon as it's ready.
     715             :              * We will only wait autovacuum_naptime seconds (up to a maximum
     716             :              * of 60 seconds) for this to happen however.  Note that failure
     717             :              * to connect to a particular database is not a problem here,
     718             :              * because the worker removes itself from the startingWorker
     719             :              * pointer before trying to connect.  Problems detected by the
     720             :              * postmaster (like fork() failure) are also reported and handled
     721             :              * differently.  The only problems that may cause this code to
     722             :              * fire are errors in the earlier sections of AutoVacWorkerMain,
     723             :              * before the worker removes the WorkerInfo from the
     724             :              * startingWorker pointer.
     725             :              */
     726           0 :             waittime = Min(autovacuum_naptime, 60) * 1000;
     727           0 :             if (TimestampDifferenceExceeds(worker->wi_launchtime, current_time,
     728             :                                            waittime))
     729             :             {
     730           0 :                 LWLockRelease(AutovacuumLock);
     731           0 :                 LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
     732             : 
     733             :                 /*
     734             :                  * No other process can put a worker in starting mode, so if
     735             :                  * startingWorker is still INVALID after exchanging our lock,
     736             :                  * we assume it's the same one we saw above (so we don't
     737             :                  * recheck the launch time).
     738             :                  */
     739           0 :                 if (AutoVacuumShmem->av_startingWorker != NULL)
     740             :                 {
     741           0 :                     worker = AutoVacuumShmem->av_startingWorker;
     742           0 :                     worker->wi_dboid = InvalidOid;
     743           0 :                     worker->wi_tableoid = InvalidOid;
     744           0 :                     worker->wi_sharedrel = false;
     745           0 :                     worker->wi_proc = NULL;
     746           0 :                     worker->wi_launchtime = 0;
     747           0 :                     dlist_push_head(&AutoVacuumShmem->av_freeWorkers,
     748             :                                     &worker->wi_links);
     749           0 :                     AutoVacuumShmem->av_startingWorker = NULL;
     750           0 :                     ereport(WARNING,
     751             :                             errmsg("autovacuum worker took too long to start; canceled"));
     752             :                 }
     753             :             }
     754             :             else
     755           0 :                 can_launch = false;
     756             :         }
     757        2600 :         LWLockRelease(AutovacuumLock);  /* either shared or exclusive */
     758             : 
     759             :         /* if we can't do anything, just go back to sleep */
     760        2600 :         if (!can_launch)
     761           0 :             continue;
     762             : 
     763             :         /* We're OK to start a new worker */
     764             : 
     765        2600 :         if (dlist_is_empty(&DatabaseList))
     766             :         {
     767             :             /*
     768             :              * Special case when the list is empty: start a worker right away.
     769             :              * This covers the initial case, when no database is in pgstats
     770             :              * (thus the list is empty).  Note that the constraints in
     771             :              * launcher_determine_sleep keep us from starting workers too
     772             :              * quickly (at most once every autovacuum_naptime when the list is
     773             :              * empty).
     774             :              */
     775          60 :             launch_worker(current_time);
     776             :         }
     777             :         else
     778             :         {
     779             :             /*
     780             :              * because rebuild_database_list constructs a list with most
     781             :              * distant adl_next_worker first, we obtain our database from the
     782             :              * tail of the list.
     783             :              */
     784             :             avl_dbase  *avdb;
     785             : 
     786        2540 :             avdb = dlist_tail_element(avl_dbase, adl_node, &DatabaseList);
     787             : 
     788             :             /*
     789             :              * launch a worker if next_worker is right now or it is in the
     790             :              * past
     791             :              */
     792        2540 :             if (TimestampDifferenceExceeds(avdb->adl_next_worker,
     793             :                                            current_time, 0))
     794          16 :                 launch_worker(current_time);
     795             :         }
     796             :     }
     797             : 
     798           0 :     AutoVacLauncherShutdown();
     799             : }
     800             : 
     801             : /*
     802             :  * Process any new interrupts.
     803             :  */
     804             : static void
     805        3208 : HandleAutoVacLauncherInterrupts(void)
     806             : {
     807             :     /* the normal shutdown case */
     808        3208 :     if (ShutdownRequestPending)
     809         608 :         AutoVacLauncherShutdown();
     810             : 
     811        2600 :     if (ConfigReloadPending)
     812             :     {
     813          52 :         ConfigReloadPending = false;
     814          52 :         ProcessConfigFile(PGC_SIGHUP);
     815             : 
     816             :         /* shutdown requested in config file? */
     817          52 :         if (!AutoVacuumingActive())
     818           0 :             AutoVacLauncherShutdown();
     819             : 
     820             :         /* rebuild the list in case the naptime changed */
     821          52 :         rebuild_database_list(InvalidOid);
     822             :     }
     823             : 
     824             :     /* Process barrier events */
     825        2600 :     if (ProcSignalBarrierPending)
     826          42 :         ProcessProcSignalBarrier();
     827             : 
     828             :     /* Perform logging of memory contexts of this process */
     829        2600 :     if (LogMemoryContextPending)
     830           0 :         ProcessLogMemoryContextInterrupt();
     831             : 
     832             :     /* Process sinval catchup interrupts that happened while sleeping */
     833        2600 :     ProcessCatchupInterrupt();
     834        2600 : }
     835             : 
     836             : /*
     837             :  * Perform a normal exit from the autovac launcher.
     838             :  */
     839             : static void
     840         608 : AutoVacLauncherShutdown(void)
     841             : {
     842         608 :     ereport(DEBUG1,
     843             :             (errmsg_internal("autovacuum launcher shutting down")));
     844         608 :     AutoVacuumShmem->av_launcherpid = 0;
     845             : 
     846         608 :     proc_exit(0);               /* done */
     847             : }
     848             : 
     849             : /*
     850             :  * Determine the time to sleep, based on the database list.
     851             :  *
     852             :  * The "canlaunch" parameter indicates whether we can start a worker right now,
     853             :  * for example due to the workers being all busy.  If this is false, we will
     854             :  * cause a long sleep, which will be interrupted when a worker exits.
     855             :  */
     856             : static void
     857        3214 : launcher_determine_sleep(bool canlaunch, bool recursing, struct timeval *nap)
     858             : {
     859             :     /*
     860             :      * We sleep until the next scheduled vacuum.  We trust that when the
     861             :      * database list was built, care was taken so that no entries have times
     862             :      * in the past; if the first entry has too close a next_worker value, or a
     863             :      * time in the past, we will sleep a small nominal time.
     864             :      */
     865        3214 :     if (!canlaunch)
     866             :     {
     867           0 :         nap->tv_sec = autovacuum_naptime;
     868           0 :         nap->tv_usec = 0;
     869             :     }
     870        3214 :     else if (!dlist_is_empty(&DatabaseList))
     871             :     {
     872        3094 :         TimestampTz current_time = GetCurrentTimestamp();
     873             :         TimestampTz next_wakeup;
     874             :         avl_dbase  *avdb;
     875             :         long        secs;
     876             :         int         usecs;
     877             : 
     878        3094 :         avdb = dlist_tail_element(avl_dbase, adl_node, &DatabaseList);
     879             : 
     880        3094 :         next_wakeup = avdb->adl_next_worker;
     881        3094 :         TimestampDifference(current_time, next_wakeup, &secs, &usecs);
     882             : 
     883        3094 :         nap->tv_sec = secs;
     884        3094 :         nap->tv_usec = usecs;
     885             :     }
     886             :     else
     887             :     {
     888             :         /* list is empty, sleep for whole autovacuum_naptime seconds  */
     889         120 :         nap->tv_sec = autovacuum_naptime;
     890         120 :         nap->tv_usec = 0;
     891             :     }
     892             : 
     893             :     /*
     894             :      * If the result is exactly zero, it means a database had an entry with
     895             :      * time in the past.  Rebuild the list so that the databases are evenly
     896             :      * distributed again, and recalculate the time to sleep.  This can happen
     897             :      * if there are more tables needing vacuum than workers, and they all take
     898             :      * longer to vacuum than autovacuum_naptime.
     899             :      *
     900             :      * We only recurse once.  rebuild_database_list should always return times
     901             :      * in the future, but it seems best not to trust too much on that.
     902             :      */
     903        3214 :     if (nap->tv_sec == 0 && nap->tv_usec == 0 && !recursing)
     904             :     {
     905           0 :         rebuild_database_list(InvalidOid);
     906           0 :         launcher_determine_sleep(canlaunch, true, nap);
     907           0 :         return;
     908             :     }
     909             : 
     910             :     /* The smallest time we'll allow the launcher to sleep. */
     911        3214 :     if (nap->tv_sec <= 0 && nap->tv_usec <= MIN_AUTOVAC_SLEEPTIME * 1000)
     912             :     {
     913           6 :         nap->tv_sec = 0;
     914           6 :         nap->tv_usec = MIN_AUTOVAC_SLEEPTIME * 1000;
     915             :     }
     916             : 
     917             :     /*
     918             :      * If the sleep time is too large, clamp it to an arbitrary maximum (plus
     919             :      * any fractional seconds, for simplicity).  This avoids an essentially
     920             :      * infinite sleep in strange cases like the system clock going backwards a
     921             :      * few years.
     922             :      */
     923        3214 :     if (nap->tv_sec > MAX_AUTOVAC_SLEEPTIME)
     924          22 :         nap->tv_sec = MAX_AUTOVAC_SLEEPTIME;
     925             : }
     926             : 
     927             : /*
     928             :  * Build an updated DatabaseList.  It must only contain databases that appear
     929             :  * in pgstats, and must be sorted by next_worker from highest to lowest,
     930             :  * distributed regularly across the next autovacuum_naptime interval.
     931             :  *
     932             :  * Receives the Oid of the database that made this list be generated (we call
     933             :  * this the "new" database, because when the database was already present on
     934             :  * the list, we expect that this function is not called at all).  The
     935             :  * preexisting list, if any, will be used to preserve the order of the
     936             :  * databases in the autovacuum_naptime period.  The new database is put at the
     937             :  * end of the interval.  The actual values are not saved, which should not be
     938             :  * much of a problem.
     939             :  */
     940             : static void
     941         674 : rebuild_database_list(Oid newdb)
     942             : {
     943             :     List       *dblist;
     944             :     ListCell   *cell;
     945             :     MemoryContext newcxt;
     946             :     MemoryContext oldcxt;
     947             :     MemoryContext tmpcxt;
     948             :     HASHCTL     hctl;
     949             :     int         score;
     950             :     int         nelems;
     951             :     HTAB       *dbhash;
     952             :     dlist_iter  iter;
     953             : 
     954         674 :     newcxt = AllocSetContextCreate(AutovacMemCxt,
     955             :                                    "Autovacuum database list",
     956             :                                    ALLOCSET_DEFAULT_SIZES);
     957         674 :     tmpcxt = AllocSetContextCreate(newcxt,
     958             :                                    "Autovacuum database list (tmp)",
     959             :                                    ALLOCSET_DEFAULT_SIZES);
     960         674 :     oldcxt = MemoryContextSwitchTo(tmpcxt);
     961             : 
     962             :     /*
     963             :      * Implementing this is not as simple as it sounds, because we need to put
     964             :      * the new database at the end of the list; next the databases that were
     965             :      * already on the list, and finally (at the tail of the list) all the
     966             :      * other databases that are not on the existing list.
     967             :      *
     968             :      * To do this, we build an empty hash table of scored databases.  We will
     969             :      * start with the lowest score (zero) for the new database, then
     970             :      * increasing scores for the databases in the existing list, in order, and
     971             :      * lastly increasing scores for all databases gotten via
     972             :      * get_database_list() that are not already on the hash.
     973             :      *
     974             :      * Then we will put all the hash elements into an array, sort the array by
     975             :      * score, and finally put the array elements into the new doubly linked
     976             :      * list.
     977             :      */
     978         674 :     hctl.keysize = sizeof(Oid);
     979         674 :     hctl.entrysize = sizeof(avl_dbase);
     980         674 :     hctl.hcxt = tmpcxt;
     981         674 :     dbhash = hash_create("autovacuum db hash", 20, &hctl, /* magic number here
     982             :                                                              * FIXME */
     983             :                          HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
     984             : 
     985             :     /* start by inserting the new database */
     986         674 :     score = 0;
     987         674 :     if (OidIsValid(newdb))
     988             :     {
     989             :         avl_dbase  *db;
     990             :         PgStat_StatDBEntry *entry;
     991             : 
     992             :         /* only consider this database if it has a pgstat entry */
     993           8 :         entry = pgstat_fetch_stat_dbentry(newdb);
     994           8 :         if (entry != NULL)
     995             :         {
     996             :             /* we assume it isn't found because the hash was just created */
     997           8 :             db = hash_search(dbhash, &newdb, HASH_ENTER, NULL);
     998             : 
     999             :             /* hash_search already filled in the key */
    1000           8 :             db->adl_score = score++;
    1001             :             /* next_worker is filled in later */
    1002             :         }
    1003             :     }
    1004             : 
    1005             :     /* Now insert the databases from the existing list */
    1006         760 :     dlist_foreach(iter, &DatabaseList)
    1007             :     {
    1008          86 :         avl_dbase  *avdb = dlist_container(avl_dbase, adl_node, iter.cur);
    1009             :         avl_dbase  *db;
    1010             :         bool        found;
    1011             :         PgStat_StatDBEntry *entry;
    1012             : 
    1013             :         /*
    1014             :          * skip databases with no stat entries -- in particular, this gets rid
    1015             :          * of dropped databases
    1016             :          */
    1017          86 :         entry = pgstat_fetch_stat_dbentry(avdb->adl_datid);
    1018          86 :         if (entry == NULL)
    1019           0 :             continue;
    1020             : 
    1021          86 :         db = hash_search(dbhash, &(avdb->adl_datid), HASH_ENTER, &found);
    1022             : 
    1023          86 :         if (!found)
    1024             :         {
    1025             :             /* hash_search already filled in the key */
    1026          86 :             db->adl_score = score++;
    1027             :             /* next_worker is filled in later */
    1028             :         }
    1029             :     }
    1030             : 
    1031             :     /* finally, insert all qualifying databases not previously inserted */
    1032         674 :     dblist = get_database_list();
    1033        2990 :     foreach(cell, dblist)
    1034             :     {
    1035        2316 :         avw_dbase  *avdb = lfirst(cell);
    1036             :         avl_dbase  *db;
    1037             :         bool        found;
    1038             :         PgStat_StatDBEntry *entry;
    1039             : 
    1040             :         /* only consider databases with a pgstat entry */
    1041        2316 :         entry = pgstat_fetch_stat_dbentry(avdb->adw_datid);
    1042        2316 :         if (entry == NULL)
    1043        1436 :             continue;
    1044             : 
    1045         880 :         db = hash_search(dbhash, &(avdb->adw_datid), HASH_ENTER, &found);
    1046             :         /* only update the score if the database was not already on the hash */
    1047         880 :         if (!found)
    1048             :         {
    1049             :             /* hash_search already filled in the key */
    1050         786 :             db->adl_score = score++;
    1051             :             /* next_worker is filled in later */
    1052             :         }
    1053             :     }
    1054         674 :     nelems = score;
    1055             : 
    1056             :     /* from here on, the allocated memory belongs to the new list */
    1057         674 :     MemoryContextSwitchTo(newcxt);
    1058         674 :     dlist_init(&DatabaseList);
    1059             : 
    1060         674 :     if (nelems > 0)
    1061             :     {
    1062             :         TimestampTz current_time;
    1063             :         int         millis_increment;
    1064             :         avl_dbase  *dbary;
    1065             :         avl_dbase  *db;
    1066             :         HASH_SEQ_STATUS seq;
    1067             :         int         i;
    1068             : 
    1069             :         /* put all the hash elements into an array */
    1070         614 :         dbary = palloc(nelems * sizeof(avl_dbase));
    1071             : 
    1072         614 :         i = 0;
    1073         614 :         hash_seq_init(&seq, dbhash);
    1074        1494 :         while ((db = hash_seq_search(&seq)) != NULL)
    1075         880 :             memcpy(&(dbary[i++]), db, sizeof(avl_dbase));
    1076             : 
    1077             :         /* sort the array */
    1078         614 :         qsort(dbary, nelems, sizeof(avl_dbase), db_comparator);
    1079             : 
    1080             :         /*
    1081             :          * Determine the time interval between databases in the schedule. If
    1082             :          * we see that the configured naptime would take us to sleep times
    1083             :          * lower than our min sleep time (which launcher_determine_sleep is
    1084             :          * coded not to allow), silently use a larger naptime (but don't touch
    1085             :          * the GUC variable).
    1086             :          */
    1087         614 :         millis_increment = 1000.0 * autovacuum_naptime / nelems;
    1088         614 :         if (millis_increment <= MIN_AUTOVAC_SLEEPTIME)
    1089           0 :             millis_increment = MIN_AUTOVAC_SLEEPTIME * 1.1;
    1090             : 
    1091         614 :         current_time = GetCurrentTimestamp();
    1092             : 
    1093             :         /*
    1094             :          * move the elements from the array into the dlist, setting the
    1095             :          * next_worker while walking the array
    1096             :          */
    1097        1494 :         for (i = 0; i < nelems; i++)
    1098             :         {
    1099         880 :             db = &(dbary[i]);
    1100             : 
    1101         880 :             current_time = TimestampTzPlusMilliseconds(current_time,
    1102             :                                                        millis_increment);
    1103         880 :             db->adl_next_worker = current_time;
    1104             : 
    1105             :             /* later elements should go closer to the head of the list */
    1106         880 :             dlist_push_head(&DatabaseList, &db->adl_node);
    1107             :         }
    1108             :     }
    1109             : 
    1110             :     /* all done, clean up memory */
    1111         674 :     if (DatabaseListCxt != NULL)
    1112          60 :         MemoryContextDelete(DatabaseListCxt);
    1113         674 :     MemoryContextDelete(tmpcxt);
    1114         674 :     DatabaseListCxt = newcxt;
    1115         674 :     MemoryContextSwitchTo(oldcxt);
    1116         674 : }
    1117             : 
    1118             : /* qsort comparator for avl_dbase, using adl_score */
    1119             : static int
    1120         362 : db_comparator(const void *a, const void *b)
    1121             : {
    1122         362 :     if (((const avl_dbase *) a)->adl_score == ((const avl_dbase *) b)->adl_score)
    1123           0 :         return 0;
    1124             :     else
    1125         362 :         return (((const avl_dbase *) a)->adl_score < ((const avl_dbase *) b)->adl_score) ? 1 : -1;
    1126             : }
    1127             : 
    1128             : /*
    1129             :  * do_start_worker
    1130             :  *
    1131             :  * Bare-bones procedure for starting an autovacuum worker from the launcher.
    1132             :  * It determines what database to work on, sets up shared memory stuff and
    1133             :  * signals postmaster to start the worker.  It fails gracefully if invoked when
    1134             :  * autovacuum_workers are already active.
    1135             :  *
    1136             :  * Return value is the OID of the database that the worker is going to process,
    1137             :  * or InvalidOid if no worker was actually started.
    1138             :  */
    1139             : static Oid
    1140          76 : do_start_worker(void)
    1141             : {
    1142             :     List       *dblist;
    1143             :     ListCell   *cell;
    1144             :     TransactionId xidForceLimit;
    1145             :     MultiXactId multiForceLimit;
    1146             :     bool        for_xid_wrap;
    1147             :     bool        for_multi_wrap;
    1148             :     avw_dbase  *avdb;
    1149             :     TimestampTz current_time;
    1150          76 :     bool        skipit = false;
    1151          76 :     Oid         retval = InvalidOid;
    1152             :     MemoryContext tmpcxt,
    1153             :                 oldcxt;
    1154             : 
    1155             :     /* return quickly when there are no free workers */
    1156          76 :     LWLockAcquire(AutovacuumLock, LW_SHARED);
    1157          76 :     if (dlist_is_empty(&AutoVacuumShmem->av_freeWorkers))
    1158             :     {
    1159           0 :         LWLockRelease(AutovacuumLock);
    1160           0 :         return InvalidOid;
    1161             :     }
    1162          76 :     LWLockRelease(AutovacuumLock);
    1163             : 
    1164             :     /*
    1165             :      * Create and switch to a temporary context to avoid leaking the memory
    1166             :      * allocated for the database list.
    1167             :      */
    1168          76 :     tmpcxt = AllocSetContextCreate(CurrentMemoryContext,
    1169             :                                    "Autovacuum start worker (tmp)",
    1170             :                                    ALLOCSET_DEFAULT_SIZES);
    1171          76 :     oldcxt = MemoryContextSwitchTo(tmpcxt);
    1172             : 
    1173             :     /* Get a list of databases */
    1174          76 :     dblist = get_database_list();
    1175             : 
    1176             :     /*
    1177             :      * Determine the oldest datfrozenxid/relfrozenxid that we will allow to
    1178             :      * pass without forcing a vacuum.  (This limit can be tightened for
    1179             :      * particular tables, but not loosened.)
    1180             :      */
    1181          76 :     recentXid = ReadNextTransactionId();
    1182          76 :     xidForceLimit = recentXid - autovacuum_freeze_max_age;
    1183             :     /* ensure it's a "normal" XID, else TransactionIdPrecedes misbehaves */
    1184             :     /* this can cause the limit to go backwards by 3, but that's OK */
    1185          76 :     if (xidForceLimit < FirstNormalTransactionId)
    1186           0 :         xidForceLimit -= FirstNormalTransactionId;
    1187             : 
    1188             :     /* Also determine the oldest datminmxid we will consider. */
    1189          76 :     recentMulti = ReadNextMultiXactId();
    1190          76 :     multiForceLimit = recentMulti - MultiXactMemberFreezeThreshold();
    1191          76 :     if (multiForceLimit < FirstMultiXactId)
    1192           0 :         multiForceLimit -= FirstMultiXactId;
    1193             : 
    1194             :     /*
    1195             :      * Choose a database to connect to.  We pick the database that was least
    1196             :      * recently auto-vacuumed, or one that needs vacuuming to prevent Xid
    1197             :      * wraparound-related data loss.  If any db at risk of Xid wraparound is
    1198             :      * found, we pick the one with oldest datfrozenxid, independently of
    1199             :      * autovacuum times; similarly we pick the one with the oldest datminmxid
    1200             :      * if any is in MultiXactId wraparound.  Note that those in Xid wraparound
    1201             :      * danger are given more priority than those in multi wraparound danger.
    1202             :      *
    1203             :      * Note that a database with no stats entry is not considered, except for
    1204             :      * Xid wraparound purposes.  The theory is that if no one has ever
    1205             :      * connected to it since the stats were last initialized, it doesn't need
    1206             :      * vacuuming.
    1207             :      *
    1208             :      * XXX This could be improved if we had more info about whether it needs
    1209             :      * vacuuming before connecting to it.  Perhaps look through the pgstats
    1210             :      * data for the database's tables?  One idea is to keep track of the
    1211             :      * number of new and dead tuples per database in pgstats.  However it
    1212             :      * isn't clear how to construct a metric that measures that and not cause
    1213             :      * starvation for less busy databases.
    1214             :      */
    1215          76 :     avdb = NULL;
    1216          76 :     for_xid_wrap = false;
    1217          76 :     for_multi_wrap = false;
    1218          76 :     current_time = GetCurrentTimestamp();
    1219         342 :     foreach(cell, dblist)
    1220             :     {
    1221         266 :         avw_dbase  *tmp = lfirst(cell);
    1222             :         dlist_iter  iter;
    1223             : 
    1224             :         /* Check to see if this one is at risk of wraparound */
    1225         266 :         if (TransactionIdPrecedes(tmp->adw_frozenxid, xidForceLimit))
    1226             :         {
    1227           0 :             if (avdb == NULL ||
    1228           0 :                 TransactionIdPrecedes(tmp->adw_frozenxid,
    1229             :                                       avdb->adw_frozenxid))
    1230           0 :                 avdb = tmp;
    1231           0 :             for_xid_wrap = true;
    1232         236 :             continue;
    1233             :         }
    1234         266 :         else if (for_xid_wrap)
    1235           0 :             continue;           /* ignore not-at-risk DBs */
    1236         266 :         else if (MultiXactIdPrecedes(tmp->adw_minmulti, multiForceLimit))
    1237             :         {
    1238           0 :             if (avdb == NULL ||
    1239           0 :                 MultiXactIdPrecedes(tmp->adw_minmulti, avdb->adw_minmulti))
    1240           0 :                 avdb = tmp;
    1241           0 :             for_multi_wrap = true;
    1242           0 :             continue;
    1243             :         }
    1244         266 :         else if (for_multi_wrap)
    1245           0 :             continue;           /* ignore not-at-risk DBs */
    1246             : 
    1247             :         /* Find pgstat entry if any */
    1248         266 :         tmp->adw_entry = pgstat_fetch_stat_dbentry(tmp->adw_datid);
    1249             : 
    1250             :         /*
    1251             :          * Skip a database with no pgstat entry; it means it hasn't seen any
    1252             :          * activity.
    1253             :          */
    1254         266 :         if (!tmp->adw_entry)
    1255         220 :             continue;
    1256             : 
    1257             :         /*
    1258             :          * Also, skip a database that appears on the database list as having
    1259             :          * been processed recently (less than autovacuum_naptime seconds ago).
    1260             :          * We do this so that we don't select a database which we just
    1261             :          * selected, but that pgstat hasn't gotten around to updating the last
    1262             :          * autovacuum time yet.
    1263             :          */
    1264          46 :         skipit = false;
    1265             : 
    1266          84 :         dlist_reverse_foreach(iter, &DatabaseList)
    1267             :         {
    1268          70 :             avl_dbase  *dbp = dlist_container(avl_dbase, adl_node, iter.cur);
    1269             : 
    1270          70 :             if (dbp->adl_datid == tmp->adw_datid)
    1271             :             {
    1272             :                 /*
    1273             :                  * Skip this database if its next_worker value falls between
    1274             :                  * the current time and the current time plus naptime.
    1275             :                  */
    1276          32 :                 if (!TimestampDifferenceExceeds(dbp->adl_next_worker,
    1277          16 :                                                 current_time, 0) &&
    1278          16 :                     !TimestampDifferenceExceeds(current_time,
    1279             :                                                 dbp->adl_next_worker,
    1280             :                                                 autovacuum_naptime * 1000))
    1281          16 :                     skipit = true;
    1282             : 
    1283          32 :                 break;
    1284             :             }
    1285             :         }
    1286          46 :         if (skipit)
    1287          16 :             continue;
    1288             : 
    1289             :         /*
    1290             :          * Remember the db with oldest autovac time.  (If we are here, both
    1291             :          * tmp->entry and db->entry must be non-null.)
    1292             :          */
    1293          30 :         if (avdb == NULL ||
    1294          14 :             tmp->adw_entry->last_autovac_time < avdb->adw_entry->last_autovac_time)
    1295          16 :             avdb = tmp;
    1296             :     }
    1297             : 
    1298             :     /* Found a database -- process it */
    1299          76 :     if (avdb != NULL)
    1300             :     {
    1301             :         WorkerInfo  worker;
    1302             :         dlist_node *wptr;
    1303             : 
    1304          16 :         LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    1305             : 
    1306             :         /*
    1307             :          * Get a worker entry from the freelist.  We checked above, so there
    1308             :          * really should be a free slot.
    1309             :          */
    1310          16 :         wptr = dlist_pop_head_node(&AutoVacuumShmem->av_freeWorkers);
    1311             : 
    1312          16 :         worker = dlist_container(WorkerInfoData, wi_links, wptr);
    1313          16 :         worker->wi_dboid = avdb->adw_datid;
    1314          16 :         worker->wi_proc = NULL;
    1315          16 :         worker->wi_launchtime = GetCurrentTimestamp();
    1316             : 
    1317          16 :         AutoVacuumShmem->av_startingWorker = worker;
    1318             : 
    1319          16 :         LWLockRelease(AutovacuumLock);
    1320             : 
    1321          16 :         SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER);
    1322             : 
    1323          16 :         retval = avdb->adw_datid;
    1324             :     }
    1325          60 :     else if (skipit)
    1326             :     {
    1327             :         /*
    1328             :          * If we skipped all databases on the list, rebuild it, because it
    1329             :          * probably contains a dropped database.
    1330             :          */
    1331           0 :         rebuild_database_list(InvalidOid);
    1332             :     }
    1333             : 
    1334          76 :     MemoryContextSwitchTo(oldcxt);
    1335          76 :     MemoryContextDelete(tmpcxt);
    1336             : 
    1337          76 :     return retval;
    1338             : }
    1339             : 
    1340             : /*
    1341             :  * launch_worker
    1342             :  *
    1343             :  * Wrapper for starting a worker from the launcher.  Besides actually starting
    1344             :  * it, update the database list to reflect the next time that another one will
    1345             :  * need to be started on the selected database.  The actual database choice is
    1346             :  * left to do_start_worker.
    1347             :  *
    1348             :  * This routine is also expected to insert an entry into the database list if
    1349             :  * the selected database was previously absent from the list.
    1350             :  */
    1351             : static void
    1352          76 : launch_worker(TimestampTz now)
    1353             : {
    1354             :     Oid         dbid;
    1355             :     dlist_iter  iter;
    1356             : 
    1357          76 :     dbid = do_start_worker();
    1358          76 :     if (OidIsValid(dbid))
    1359             :     {
    1360          16 :         bool        found = false;
    1361             : 
    1362             :         /*
    1363             :          * Walk the database list and update the corresponding entry.  If the
    1364             :          * database is not on the list, we'll recreate the list.
    1365             :          */
    1366          40 :         dlist_foreach(iter, &DatabaseList)
    1367             :         {
    1368          32 :             avl_dbase  *avdb = dlist_container(avl_dbase, adl_node, iter.cur);
    1369             : 
    1370          32 :             if (avdb->adl_datid == dbid)
    1371             :             {
    1372           8 :                 found = true;
    1373             : 
    1374             :                 /*
    1375             :                  * add autovacuum_naptime seconds to the current time, and use
    1376             :                  * that as the new "next_worker" field for this database.
    1377             :                  */
    1378           8 :                 avdb->adl_next_worker =
    1379           8 :                     TimestampTzPlusMilliseconds(now, autovacuum_naptime * 1000);
    1380             : 
    1381           8 :                 dlist_move_head(&DatabaseList, iter.cur);
    1382           8 :                 break;
    1383             :             }
    1384             :         }
    1385             : 
    1386             :         /*
    1387             :          * If the database was not present in the database list, we rebuild
    1388             :          * the list.  It's possible that the database does not get into the
    1389             :          * list anyway, for example if it's a database that doesn't have a
    1390             :          * pgstat entry, but this is not a problem because we don't want to
    1391             :          * schedule workers regularly into those in any case.
    1392             :          */
    1393          16 :         if (!found)
    1394           8 :             rebuild_database_list(dbid);
    1395             :     }
    1396          76 : }
    1397             : 
    1398             : /*
    1399             :  * Called from postmaster to signal a failure to fork a process to become
    1400             :  * worker.  The postmaster should kill(SIGUSR2) the launcher shortly
    1401             :  * after calling this function.
    1402             :  */
    1403             : void
    1404           0 : AutoVacWorkerFailed(void)
    1405             : {
    1406           0 :     AutoVacuumShmem->av_signal[AutoVacForkFailed] = true;
    1407           0 : }
    1408             : 
    1409             : /* SIGUSR2: a worker is up and running, or just finished, or failed to fork */
    1410             : static void
    1411          32 : avl_sigusr2_handler(SIGNAL_ARGS)
    1412             : {
    1413          32 :     int         save_errno = errno;
    1414             : 
    1415          32 :     got_SIGUSR2 = true;
    1416          32 :     SetLatch(MyLatch);
    1417             : 
    1418          32 :     errno = save_errno;
    1419          32 : }
    1420             : 
    1421             : 
    1422             : /********************************************************************
    1423             :  *                    AUTOVACUUM WORKER CODE
    1424             :  ********************************************************************/
    1425             : 
    1426             : #ifdef EXEC_BACKEND
    1427             : /*
    1428             :  * forkexec routines for the autovacuum worker.
    1429             :  *
    1430             :  * Format up the arglist, then fork and exec.
    1431             :  */
    1432             : static pid_t
    1433             : avworker_forkexec(void)
    1434             : {
    1435             :     char       *av[10];
    1436             :     int         ac = 0;
    1437             : 
    1438             :     av[ac++] = "postgres";
    1439             :     av[ac++] = "--forkavworker";
    1440             :     av[ac++] = NULL;            /* filled in by postmaster_forkexec */
    1441             :     av[ac] = NULL;
    1442             : 
    1443             :     Assert(ac < lengthof(av));
    1444             : 
    1445             :     return postmaster_forkexec(ac, av);
    1446             : }
    1447             : #endif
    1448             : 
    1449             : /*
    1450             :  * Main entry point for autovacuum worker process.
    1451             :  *
    1452             :  * This code is heavily based on pgarch.c, q.v.
    1453             :  */
    1454             : int
    1455          16 : StartAutoVacWorker(void)
    1456             : {
    1457             :     pid_t       worker_pid;
    1458             : 
    1459             : #ifdef EXEC_BACKEND
    1460             :     switch ((worker_pid = avworker_forkexec()))
    1461             : #else
    1462          16 :     switch ((worker_pid = fork_process()))
    1463             : #endif
    1464             :     {
    1465           0 :         case -1:
    1466           0 :             ereport(LOG,
    1467             :                     (errmsg("could not fork autovacuum worker process: %m")));
    1468           0 :             return 0;
    1469             : 
    1470             : #ifndef EXEC_BACKEND
    1471          16 :         case 0:
    1472             :             /* in postmaster child ... */
    1473          16 :             InitPostmasterChild();
    1474             : 
    1475             :             /* Close the postmaster's sockets */
    1476          16 :             ClosePostmasterPorts(false);
    1477             : 
    1478          16 :             AutoVacWorkerMain(0, NULL);
    1479             :             break;
    1480             : #endif
    1481          16 :         default:
    1482          16 :             return (int) worker_pid;
    1483             :     }
    1484             : 
    1485             :     /* shouldn't get here */
    1486             :     return 0;
    1487             : }
    1488             : 
    1489             : /*
    1490             :  * AutoVacWorkerMain
    1491             :  */
    1492             : NON_EXEC_STATIC void
    1493          16 : AutoVacWorkerMain(int argc, char *argv[])
    1494             : {
    1495             :     sigjmp_buf  local_sigjmp_buf;
    1496             :     Oid         dbid;
    1497             : 
    1498          16 :     am_autovacuum_worker = true;
    1499             : 
    1500          16 :     MyBackendType = B_AUTOVAC_WORKER;
    1501          16 :     init_ps_display(NULL);
    1502             : 
    1503          16 :     SetProcessingMode(InitProcessing);
    1504             : 
    1505             :     /*
    1506             :      * Set up signal handlers.  We operate on databases much like a regular
    1507             :      * backend, so we use the same signal handling.  See equivalent code in
    1508             :      * tcop/postgres.c.
    1509             :      */
    1510          16 :     pqsignal(SIGHUP, SignalHandlerForConfigReload);
    1511             : 
    1512             :     /*
    1513             :      * SIGINT is used to signal canceling the current table's vacuum; SIGTERM
    1514             :      * means abort and exit cleanly, and SIGQUIT means abandon ship.
    1515             :      */
    1516          16 :     pqsignal(SIGINT, StatementCancelHandler);
    1517          16 :     pqsignal(SIGTERM, die);
    1518             :     /* SIGQUIT handler was already set up by InitPostmasterChild */
    1519             : 
    1520          16 :     InitializeTimeouts();       /* establishes SIGALRM handler */
    1521             : 
    1522          16 :     pqsignal(SIGPIPE, SIG_IGN);
    1523          16 :     pqsignal(SIGUSR1, procsignal_sigusr1_handler);
    1524          16 :     pqsignal(SIGUSR2, SIG_IGN);
    1525          16 :     pqsignal(SIGFPE, FloatExceptionHandler);
    1526          16 :     pqsignal(SIGCHLD, SIG_DFL);
    1527             : 
    1528             :     /*
    1529             :      * Create a per-backend PGPROC struct in shared memory.  We must do this
    1530             :      * before we can use LWLocks or access any shared memory.
    1531             :      */
    1532          16 :     InitProcess();
    1533             : 
    1534             :     /* Early initialization */
    1535          16 :     BaseInit();
    1536             : 
    1537             :     /*
    1538             :      * If an exception is encountered, processing resumes here.
    1539             :      *
    1540             :      * Unlike most auxiliary processes, we don't attempt to continue
    1541             :      * processing after an error; we just clean up and exit.  The autovac
    1542             :      * launcher is responsible for spawning another worker later.
    1543             :      *
    1544             :      * Note that we use sigsetjmp(..., 1), so that the prevailing signal mask
    1545             :      * (to wit, BlockSig) will be restored when longjmp'ing to here.  Thus,
    1546             :      * signals other than SIGQUIT will be blocked until we exit.  It might
    1547             :      * seem that this policy makes the HOLD_INTERRUPTS() call redundant, but
    1548             :      * it is not since InterruptPending might be set already.
    1549             :      */
    1550          16 :     if (sigsetjmp(local_sigjmp_buf, 1) != 0)
    1551             :     {
    1552             :         /* since not using PG_TRY, must reset error stack by hand */
    1553           0 :         error_context_stack = NULL;
    1554             : 
    1555             :         /* Prevents interrupts while cleaning up */
    1556           0 :         HOLD_INTERRUPTS();
    1557             : 
    1558             :         /* Report the error to the server log */
    1559           0 :         EmitErrorReport();
    1560             : 
    1561             :         /*
    1562             :          * We can now go away.  Note that because we called InitProcess, a
    1563             :          * callback was registered to do ProcKill, which will clean up
    1564             :          * necessary state.
    1565             :          */
    1566           0 :         proc_exit(0);
    1567             :     }
    1568             : 
    1569             :     /* We can now handle ereport(ERROR) */
    1570          16 :     PG_exception_stack = &local_sigjmp_buf;
    1571             : 
    1572          16 :     sigprocmask(SIG_SETMASK, &UnBlockSig, NULL);
    1573             : 
    1574             :     /*
    1575             :      * Set always-secure search path, so malicious users can't redirect user
    1576             :      * code (e.g. pg_index.indexprs).  (That code runs in a
    1577             :      * SECURITY_RESTRICTED_OPERATION sandbox, so malicious users could not
    1578             :      * take control of the entire autovacuum worker in any case.)
    1579             :      */
    1580          16 :     SetConfigOption("search_path", "", PGC_SUSET, PGC_S_OVERRIDE);
    1581             : 
    1582             :     /*
    1583             :      * Force zero_damaged_pages OFF in the autovac process, even if it is set
    1584             :      * in postgresql.conf.  We don't really want such a dangerous option being
    1585             :      * applied non-interactively.
    1586             :      */
    1587          16 :     SetConfigOption("zero_damaged_pages", "false", PGC_SUSET, PGC_S_OVERRIDE);
    1588             : 
    1589             :     /*
    1590             :      * Force settable timeouts off to avoid letting these settings prevent
    1591             :      * regular maintenance from being executed.
    1592             :      */
    1593          16 :     SetConfigOption("statement_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
    1594          16 :     SetConfigOption("lock_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
    1595          16 :     SetConfigOption("idle_in_transaction_session_timeout", "0",
    1596             :                     PGC_SUSET, PGC_S_OVERRIDE);
    1597             : 
    1598             :     /*
    1599             :      * Force default_transaction_isolation to READ COMMITTED.  We don't want
    1600             :      * to pay the overhead of serializable mode, nor add any risk of causing
    1601             :      * deadlocks or delaying other transactions.
    1602             :      */
    1603          16 :     SetConfigOption("default_transaction_isolation", "read committed",
    1604             :                     PGC_SUSET, PGC_S_OVERRIDE);
    1605             : 
    1606             :     /*
    1607             :      * Force synchronous replication off to allow regular maintenance even if
    1608             :      * we are waiting for standbys to connect. This is important to ensure we
    1609             :      * aren't blocked from performing anti-wraparound tasks.
    1610             :      */
    1611          16 :     if (synchronous_commit > SYNCHRONOUS_COMMIT_LOCAL_FLUSH)
    1612          16 :         SetConfigOption("synchronous_commit", "local",
    1613             :                         PGC_SUSET, PGC_S_OVERRIDE);
    1614             : 
    1615             :     /*
    1616             :      * Even when system is configured to use a different fetch consistency,
    1617             :      * for autovac we always want fresh stats.
    1618             :      */
    1619          16 :     SetConfigOption("stats_fetch_consistency", "none", PGC_SUSET, PGC_S_OVERRIDE);
    1620             : 
    1621             :     /*
    1622             :      * Get the info about the database we're going to work on.
    1623             :      */
    1624          16 :     LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    1625             : 
    1626             :     /*
    1627             :      * beware of startingWorker being INVALID; this should normally not
    1628             :      * happen, but if a worker fails after forking and before this, the
    1629             :      * launcher might have decided to remove it from the queue and start
    1630             :      * again.
    1631             :      */
    1632          16 :     if (AutoVacuumShmem->av_startingWorker != NULL)
    1633             :     {
    1634          16 :         MyWorkerInfo = AutoVacuumShmem->av_startingWorker;
    1635          16 :         dbid = MyWorkerInfo->wi_dboid;
    1636          16 :         MyWorkerInfo->wi_proc = MyProc;
    1637             : 
    1638             :         /* insert into the running list */
    1639          16 :         dlist_push_head(&AutoVacuumShmem->av_runningWorkers,
    1640          16 :                         &MyWorkerInfo->wi_links);
    1641             : 
    1642             :         /*
    1643             :          * remove from the "starting" pointer, so that the launcher can start
    1644             :          * a new worker if required
    1645             :          */
    1646          16 :         AutoVacuumShmem->av_startingWorker = NULL;
    1647          16 :         LWLockRelease(AutovacuumLock);
    1648             : 
    1649          16 :         on_shmem_exit(FreeWorkerInfo, 0);
    1650             : 
    1651             :         /* wake up the launcher */
    1652          16 :         if (AutoVacuumShmem->av_launcherpid != 0)
    1653          16 :             kill(AutoVacuumShmem->av_launcherpid, SIGUSR2);
    1654             :     }
    1655             :     else
    1656             :     {
    1657             :         /* no worker entry for me, go away */
    1658           0 :         elog(WARNING, "autovacuum worker started without a worker entry");
    1659           0 :         dbid = InvalidOid;
    1660           0 :         LWLockRelease(AutovacuumLock);
    1661             :     }
    1662             : 
    1663          16 :     if (OidIsValid(dbid))
    1664             :     {
    1665             :         char        dbname[NAMEDATALEN];
    1666             : 
    1667             :         /*
    1668             :          * Report autovac startup to the cumulative stats system.  We
    1669             :          * deliberately do this before InitPostgres, so that the
    1670             :          * last_autovac_time will get updated even if the connection attempt
    1671             :          * fails.  This is to prevent autovac from getting "stuck" repeatedly
    1672             :          * selecting an unopenable database, rather than making any progress
    1673             :          * on stuff it can connect to.
    1674             :          */
    1675          16 :         pgstat_report_autovac(dbid);
    1676             : 
    1677             :         /*
    1678             :          * Connect to the selected database, specifying no particular user
    1679             :          *
    1680             :          * Note: if we have selected a just-deleted database (due to using
    1681             :          * stale stats info), we'll fail and exit here.
    1682             :          */
    1683          16 :         InitPostgres(NULL, dbid, NULL, InvalidOid, 0, dbname);
    1684          16 :         SetProcessingMode(NormalProcessing);
    1685          16 :         set_ps_display(dbname);
    1686          16 :         ereport(DEBUG1,
    1687             :                 (errmsg_internal("autovacuum: processing database \"%s\"", dbname)));
    1688             : 
    1689          16 :         if (PostAuthDelay)
    1690           0 :             pg_usleep(PostAuthDelay * 1000000L);
    1691             : 
    1692             :         /* And do an appropriate amount of work */
    1693          16 :         recentXid = ReadNextTransactionId();
    1694          16 :         recentMulti = ReadNextMultiXactId();
    1695          16 :         do_autovacuum();
    1696             :     }
    1697             : 
    1698             :     /*
    1699             :      * The launcher will be notified of my death in ProcKill, *if* we managed
    1700             :      * to get a worker slot at all
    1701             :      */
    1702             : 
    1703             :     /* All done, go away */
    1704          16 :     proc_exit(0);
    1705             : }
    1706             : 
    1707             : /*
    1708             :  * Return a WorkerInfo to the free list
    1709             :  */
    1710             : static void
    1711          16 : FreeWorkerInfo(int code, Datum arg)
    1712             : {
    1713          16 :     if (MyWorkerInfo != NULL)
    1714             :     {
    1715          16 :         LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    1716             : 
    1717             :         /*
    1718             :          * Wake the launcher up so that he can launch a new worker immediately
    1719             :          * if required.  We only save the launcher's PID in local memory here;
    1720             :          * the actual signal will be sent when the PGPROC is recycled.  Note
    1721             :          * that we always do this, so that the launcher can rebalance the cost
    1722             :          * limit setting of the remaining workers.
    1723             :          *
    1724             :          * We somewhat ignore the risk that the launcher changes its PID
    1725             :          * between us reading it and the actual kill; we expect ProcKill to be
    1726             :          * called shortly after us, and we assume that PIDs are not reused too
    1727             :          * quickly after a process exits.
    1728             :          */
    1729          16 :         AutovacuumLauncherPid = AutoVacuumShmem->av_launcherpid;
    1730             : 
    1731          16 :         dlist_delete(&MyWorkerInfo->wi_links);
    1732          16 :         MyWorkerInfo->wi_dboid = InvalidOid;
    1733          16 :         MyWorkerInfo->wi_tableoid = InvalidOid;
    1734          16 :         MyWorkerInfo->wi_sharedrel = false;
    1735          16 :         MyWorkerInfo->wi_proc = NULL;
    1736          16 :         MyWorkerInfo->wi_launchtime = 0;
    1737          16 :         pg_atomic_clear_flag(&MyWorkerInfo->wi_dobalance);
    1738          16 :         dlist_push_head(&AutoVacuumShmem->av_freeWorkers,
    1739          16 :                         &MyWorkerInfo->wi_links);
    1740             :         /* not mine anymore */
    1741          16 :         MyWorkerInfo = NULL;
    1742             : 
    1743             :         /*
    1744             :          * now that we're inactive, cause a rebalancing of the surviving
    1745             :          * workers
    1746             :          */
    1747          16 :         AutoVacuumShmem->av_signal[AutoVacRebalance] = true;
    1748          16 :         LWLockRelease(AutovacuumLock);
    1749             :     }
    1750          16 : }
    1751             : 
    1752             : /*
    1753             :  * Update vacuum cost-based delay-related parameters for autovacuum workers and
    1754             :  * backends executing VACUUM or ANALYZE using the value of relevant GUCs and
    1755             :  * global state. This must be called during setup for vacuum and after every
    1756             :  * config reload to ensure up-to-date values.
    1757             :  */
    1758             : void
    1759        9710 : VacuumUpdateCosts(void)
    1760             : {
    1761        9710 :     if (MyWorkerInfo)
    1762             :     {
    1763         404 :         if (av_storage_param_cost_delay >= 0)
    1764           0 :             vacuum_cost_delay = av_storage_param_cost_delay;
    1765         404 :         else if (autovacuum_vac_cost_delay >= 0)
    1766         404 :             vacuum_cost_delay = autovacuum_vac_cost_delay;
    1767             :         else
    1768             :             /* fall back to VacuumCostDelay */
    1769           0 :             vacuum_cost_delay = VacuumCostDelay;
    1770             : 
    1771         404 :         AutoVacuumUpdateCostLimit();
    1772             :     }
    1773             :     else
    1774             :     {
    1775             :         /* Must be explicit VACUUM or ANALYZE */
    1776        9306 :         vacuum_cost_delay = VacuumCostDelay;
    1777        9306 :         vacuum_cost_limit = VacuumCostLimit;
    1778             :     }
    1779             : 
    1780             :     /*
    1781             :      * If configuration changes are allowed to impact VacuumCostActive, make
    1782             :      * sure it is updated.
    1783             :      */
    1784        9710 :     if (VacuumFailsafeActive)
    1785             :         Assert(!VacuumCostActive);
    1786        9710 :     else if (vacuum_cost_delay > 0)
    1787         404 :         VacuumCostActive = true;
    1788             :     else
    1789             :     {
    1790        9306 :         VacuumCostActive = false;
    1791        9306 :         VacuumCostBalance = 0;
    1792             :     }
    1793             : 
    1794             :     /*
    1795             :      * Since the cost logging requires a lock, avoid rendering the log message
    1796             :      * in case we are using a message level where the log wouldn't be emitted.
    1797             :      */
    1798        9710 :     if (MyWorkerInfo && message_level_is_interesting(DEBUG2))
    1799             :     {
    1800             :         Oid         dboid,
    1801             :                     tableoid;
    1802             : 
    1803             :         Assert(!LWLockHeldByMe(AutovacuumLock));
    1804             : 
    1805           0 :         LWLockAcquire(AutovacuumLock, LW_SHARED);
    1806           0 :         dboid = MyWorkerInfo->wi_dboid;
    1807           0 :         tableoid = MyWorkerInfo->wi_tableoid;
    1808           0 :         LWLockRelease(AutovacuumLock);
    1809             : 
    1810           0 :         elog(DEBUG2,
    1811             :              "Autovacuum VacuumUpdateCosts(db=%u, rel=%u, dobalance=%s, cost_limit=%d, cost_delay=%g active=%s failsafe=%s)",
    1812             :              dboid, tableoid, pg_atomic_unlocked_test_flag(&MyWorkerInfo->wi_dobalance) ? "no" : "yes",
    1813             :              vacuum_cost_limit, vacuum_cost_delay,
    1814             :              vacuum_cost_delay > 0 ? "yes" : "no",
    1815             :              VacuumFailsafeActive ? "yes" : "no");
    1816             :     }
    1817        9710 : }
    1818             : 
    1819             : /*
    1820             :  * Update vacuum_cost_limit with the correct value for an autovacuum worker,
    1821             :  * given the value of other relevant cost limit parameters and the number of
    1822             :  * workers across which the limit must be balanced. Autovacuum workers must
    1823             :  * call this regularly in case av_nworkersForBalance has been updated by
    1824             :  * another worker or by the autovacuum launcher. They must also call it after a
    1825             :  * config reload.
    1826             :  */
    1827             : void
    1828         786 : AutoVacuumUpdateCostLimit(void)
    1829             : {
    1830         786 :     if (!MyWorkerInfo)
    1831           0 :         return;
    1832             : 
    1833             :     /*
    1834             :      * note: in cost_limit, zero also means use value from elsewhere, because
    1835             :      * zero is not a valid value.
    1836             :      */
    1837             : 
    1838         786 :     if (av_storage_param_cost_limit > 0)
    1839           0 :         vacuum_cost_limit = av_storage_param_cost_limit;
    1840             :     else
    1841             :     {
    1842             :         int         nworkers_for_balance;
    1843             : 
    1844         786 :         if (autovacuum_vac_cost_limit > 0)
    1845           0 :             vacuum_cost_limit = autovacuum_vac_cost_limit;
    1846             :         else
    1847         786 :             vacuum_cost_limit = VacuumCostLimit;
    1848             : 
    1849             :         /* Only balance limit if no cost-related storage parameters specified */
    1850         786 :         if (pg_atomic_unlocked_test_flag(&MyWorkerInfo->wi_dobalance))
    1851           0 :             return;
    1852             : 
    1853             :         Assert(vacuum_cost_limit > 0);
    1854             : 
    1855         786 :         nworkers_for_balance = pg_atomic_read_u32(&AutoVacuumShmem->av_nworkersForBalance);
    1856             : 
    1857             :         /* There is at least 1 autovac worker (this worker) */
    1858         786 :         if (nworkers_for_balance <= 0)
    1859           0 :             elog(ERROR, "nworkers_for_balance must be > 0");
    1860             : 
    1861         786 :         vacuum_cost_limit = Max(vacuum_cost_limit / nworkers_for_balance, 1);
    1862             :     }
    1863             : }
    1864             : 
    1865             : /*
    1866             :  * autovac_recalculate_workers_for_balance
    1867             :  *      Recalculate the number of workers to consider, given cost-related
    1868             :  *      storage parameters and the current number of active workers.
    1869             :  *
    1870             :  * Caller must hold the AutovacuumLock in at least shared mode to access
    1871             :  * worker->wi_proc.
    1872             :  */
    1873             : static void
    1874         218 : autovac_recalculate_workers_for_balance(void)
    1875             : {
    1876             :     dlist_iter  iter;
    1877             :     int         orig_nworkers_for_balance;
    1878         218 :     int         nworkers_for_balance = 0;
    1879             : 
    1880             :     Assert(LWLockHeldByMe(AutovacuumLock));
    1881             : 
    1882         218 :     orig_nworkers_for_balance =
    1883         218 :         pg_atomic_read_u32(&AutoVacuumShmem->av_nworkersForBalance);
    1884             : 
    1885         420 :     dlist_foreach(iter, &AutoVacuumShmem->av_runningWorkers)
    1886             :     {
    1887         202 :         WorkerInfo  worker = dlist_container(WorkerInfoData, wi_links, iter.cur);
    1888             : 
    1889         404 :         if (worker->wi_proc == NULL ||
    1890         202 :             pg_atomic_unlocked_test_flag(&worker->wi_dobalance))
    1891           0 :             continue;
    1892             : 
    1893         202 :         nworkers_for_balance++;
    1894             :     }
    1895             : 
    1896         218 :     if (nworkers_for_balance != orig_nworkers_for_balance)
    1897          28 :         pg_atomic_write_u32(&AutoVacuumShmem->av_nworkersForBalance,
    1898             :                             nworkers_for_balance);
    1899         218 : }
    1900             : 
    1901             : /*
    1902             :  * get_database_list
    1903             :  *      Return a list of all databases found in pg_database.
    1904             :  *
    1905             :  * The list and associated data is allocated in the caller's memory context,
    1906             :  * which is in charge of ensuring that it's properly cleaned up afterwards.
    1907             :  *
    1908             :  * Note: this is the only function in which the autovacuum launcher uses a
    1909             :  * transaction.  Although we aren't attached to any particular database and
    1910             :  * therefore can't access most catalogs, we do have enough infrastructure
    1911             :  * to do a seqscan on pg_database.
    1912             :  */
    1913             : static List *
    1914         750 : get_database_list(void)
    1915             : {
    1916         750 :     List       *dblist = NIL;
    1917             :     Relation    rel;
    1918             :     TableScanDesc scan;
    1919             :     HeapTuple   tup;
    1920             :     MemoryContext resultcxt;
    1921             : 
    1922             :     /* This is the context that we will allocate our output data in */
    1923         750 :     resultcxt = CurrentMemoryContext;
    1924             : 
    1925             :     /*
    1926             :      * Start a transaction so we can access pg_database, and get a snapshot.
    1927             :      * We don't have a use for the snapshot itself, but we're interested in
    1928             :      * the secondary effect that it sets RecentGlobalXmin.  (This is critical
    1929             :      * for anything that reads heap pages, because HOT may decide to prune
    1930             :      * them even if the process doesn't attempt to modify any tuples.)
    1931             :      *
    1932             :      * FIXME: This comment is inaccurate / the code buggy. A snapshot that is
    1933             :      * not pushed/active does not reliably prevent HOT pruning (->xmin could
    1934             :      * e.g. be cleared when cache invalidations are processed).
    1935             :      */
    1936         750 :     StartTransactionCommand();
    1937         750 :     (void) GetTransactionSnapshot();
    1938             : 
    1939         750 :     rel = table_open(DatabaseRelationId, AccessShareLock);
    1940         750 :     scan = table_beginscan_catalog(rel, 0, NULL);
    1941             : 
    1942        3334 :     while (HeapTupleIsValid(tup = heap_getnext(scan, ForwardScanDirection)))
    1943             :     {
    1944        2584 :         Form_pg_database pgdatabase = (Form_pg_database) GETSTRUCT(tup);
    1945             :         avw_dbase  *avdb;
    1946             :         MemoryContext oldcxt;
    1947             : 
    1948             :         /*
    1949             :          * If database has partially been dropped, we can't, nor need to,
    1950             :          * vacuum it.
    1951             :          */
    1952        2584 :         if (database_is_invalid_form(pgdatabase))
    1953             :         {
    1954           2 :             elog(DEBUG2,
    1955             :                  "autovacuum: skipping invalid database \"%s\"",
    1956             :                  NameStr(pgdatabase->datname));
    1957           2 :             continue;
    1958             :         }
    1959             : 
    1960             :         /*
    1961             :          * Allocate our results in the caller's context, not the
    1962             :          * transaction's. We do this inside the loop, and restore the original
    1963             :          * context at the end, so that leaky things like heap_getnext() are
    1964             :          * not called in a potentially long-lived context.
    1965             :          */
    1966        2582 :         oldcxt = MemoryContextSwitchTo(resultcxt);
    1967             : 
    1968        2582 :         avdb = (avw_dbase *) palloc(sizeof(avw_dbase));
    1969             : 
    1970        2582 :         avdb->adw_datid = pgdatabase->oid;
    1971        2582 :         avdb->adw_name = pstrdup(NameStr(pgdatabase->datname));
    1972        2582 :         avdb->adw_frozenxid = pgdatabase->datfrozenxid;
    1973        2582 :         avdb->adw_minmulti = pgdatabase->datminmxid;
    1974             :         /* this gets set later: */
    1975        2582 :         avdb->adw_entry = NULL;
    1976             : 
    1977        2582 :         dblist = lappend(dblist, avdb);
    1978        2582 :         MemoryContextSwitchTo(oldcxt);
    1979             :     }
    1980             : 
    1981         750 :     table_endscan(scan);
    1982         750 :     table_close(rel, AccessShareLock);
    1983             : 
    1984         750 :     CommitTransactionCommand();
    1985             : 
    1986             :     /* Be sure to restore caller's memory context */
    1987         750 :     MemoryContextSwitchTo(resultcxt);
    1988             : 
    1989         750 :     return dblist;
    1990             : }
    1991             : 
    1992             : /*
    1993             :  * Process a database table-by-table
    1994             :  *
    1995             :  * Note that CHECK_FOR_INTERRUPTS is supposed to be used in certain spots in
    1996             :  * order not to ignore shutdown commands for too long.
    1997             :  */
    1998             : static void
    1999          16 : do_autovacuum(void)
    2000             : {
    2001             :     Relation    classRel;
    2002             :     HeapTuple   tuple;
    2003             :     TableScanDesc relScan;
    2004             :     Form_pg_database dbForm;
    2005          16 :     List       *table_oids = NIL;
    2006          16 :     List       *orphan_oids = NIL;
    2007             :     HASHCTL     ctl;
    2008             :     HTAB       *table_toast_map;
    2009             :     ListCell   *volatile cell;
    2010             :     BufferAccessStrategy bstrategy;
    2011             :     ScanKeyData key;
    2012             :     TupleDesc   pg_class_desc;
    2013             :     int         effective_multixact_freeze_max_age;
    2014          16 :     bool        did_vacuum = false;
    2015          16 :     bool        found_concurrent_worker = false;
    2016             :     int         i;
    2017             : 
    2018             :     /*
    2019             :      * StartTransactionCommand and CommitTransactionCommand will automatically
    2020             :      * switch to other contexts.  We need this one to keep the list of
    2021             :      * relations to vacuum/analyze across transactions.
    2022             :      */
    2023          16 :     AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,
    2024             :                                           "Autovacuum worker",
    2025             :                                           ALLOCSET_DEFAULT_SIZES);
    2026          16 :     MemoryContextSwitchTo(AutovacMemCxt);
    2027             : 
    2028             :     /* Start a transaction so our commands have one to play into. */
    2029          16 :     StartTransactionCommand();
    2030             : 
    2031             :     /*
    2032             :      * Compute the multixact age for which freezing is urgent.  This is
    2033             :      * normally autovacuum_multixact_freeze_max_age, but may be less if we are
    2034             :      * short of multixact member space.
    2035             :      */
    2036          16 :     effective_multixact_freeze_max_age = MultiXactMemberFreezeThreshold();
    2037             : 
    2038             :     /*
    2039             :      * Find the pg_database entry and select the default freeze ages. We use
    2040             :      * zero in template and nonconnectable databases, else the system-wide
    2041             :      * default.
    2042             :      */
    2043          16 :     tuple = SearchSysCache1(DATABASEOID, ObjectIdGetDatum(MyDatabaseId));
    2044          16 :     if (!HeapTupleIsValid(tuple))
    2045           0 :         elog(ERROR, "cache lookup failed for database %u", MyDatabaseId);
    2046          16 :     dbForm = (Form_pg_database) GETSTRUCT(tuple);
    2047             : 
    2048          16 :     if (dbForm->datistemplate || !dbForm->datallowconn)
    2049             :     {
    2050           2 :         default_freeze_min_age = 0;
    2051           2 :         default_freeze_table_age = 0;
    2052           2 :         default_multixact_freeze_min_age = 0;
    2053           2 :         default_multixact_freeze_table_age = 0;
    2054             :     }
    2055             :     else
    2056             :     {
    2057          14 :         default_freeze_min_age = vacuum_freeze_min_age;
    2058          14 :         default_freeze_table_age = vacuum_freeze_table_age;
    2059          14 :         default_multixact_freeze_min_age = vacuum_multixact_freeze_min_age;
    2060          14 :         default_multixact_freeze_table_age = vacuum_multixact_freeze_table_age;
    2061             :     }
    2062             : 
    2063          16 :     ReleaseSysCache(tuple);
    2064             : 
    2065             :     /* StartTransactionCommand changed elsewhere */
    2066          16 :     MemoryContextSwitchTo(AutovacMemCxt);
    2067             : 
    2068          16 :     classRel = table_open(RelationRelationId, AccessShareLock);
    2069             : 
    2070             :     /* create a copy so we can use it after closing pg_class */
    2071          16 :     pg_class_desc = CreateTupleDescCopy(RelationGetDescr(classRel));
    2072             : 
    2073             :     /* create hash table for toast <-> main relid mapping */
    2074          16 :     ctl.keysize = sizeof(Oid);
    2075          16 :     ctl.entrysize = sizeof(av_relation);
    2076             : 
    2077          16 :     table_toast_map = hash_create("TOAST to main relid map",
    2078             :                                   100,
    2079             :                                   &ctl,
    2080             :                                   HASH_ELEM | HASH_BLOBS);
    2081             : 
    2082             :     /*
    2083             :      * Scan pg_class to determine which tables to vacuum.
    2084             :      *
    2085             :      * We do this in two passes: on the first one we collect the list of plain
    2086             :      * relations and materialized views, and on the second one we collect
    2087             :      * TOAST tables. The reason for doing the second pass is that during it we
    2088             :      * want to use the main relation's pg_class.reloptions entry if the TOAST
    2089             :      * table does not have any, and we cannot obtain it unless we know
    2090             :      * beforehand what's the main table OID.
    2091             :      *
    2092             :      * We need to check TOAST tables separately because in cases with short,
    2093             :      * wide tables there might be proportionally much more activity in the
    2094             :      * TOAST table than in its parent.
    2095             :      */
    2096          16 :     relScan = table_beginscan_catalog(classRel, 0, NULL);
    2097             : 
    2098             :     /*
    2099             :      * On the first pass, we collect main tables to vacuum, and also the main
    2100             :      * table relid to TOAST relid mapping.
    2101             :      */
    2102       11030 :     while ((tuple = heap_getnext(relScan, ForwardScanDirection)) != NULL)
    2103             :     {
    2104       11014 :         Form_pg_class classForm = (Form_pg_class) GETSTRUCT(tuple);
    2105             :         PgStat_StatTabEntry *tabentry;
    2106             :         AutoVacOpts *relopts;
    2107             :         Oid         relid;
    2108             :         bool        dovacuum;
    2109             :         bool        doanalyze;
    2110             :         bool        wraparound;
    2111             : 
    2112       11014 :         if (classForm->relkind != RELKIND_RELATION &&
    2113        8276 :             classForm->relkind != RELKIND_MATVIEW)
    2114        8260 :             continue;
    2115             : 
    2116        2768 :         relid = classForm->oid;
    2117             : 
    2118             :         /*
    2119             :          * Check if it is a temp table (presumably, of some other backend's).
    2120             :          * We cannot safely process other backends' temp tables.
    2121             :          */
    2122        2768 :         if (classForm->relpersistence == RELPERSISTENCE_TEMP)
    2123             :         {
    2124             :             /*
    2125             :              * We just ignore it if the owning backend is still active and
    2126             :              * using the temporary schema.  Also, for safety, ignore it if the
    2127             :              * namespace doesn't exist or isn't a temp namespace after all.
    2128             :              */
    2129          14 :             if (checkTempNamespaceStatus(classForm->relnamespace) == TEMP_NAMESPACE_IDLE)
    2130             :             {
    2131             :                 /*
    2132             :                  * The table seems to be orphaned -- although it might be that
    2133             :                  * the owning backend has already deleted it and exited; our
    2134             :                  * pg_class scan snapshot is not necessarily up-to-date
    2135             :                  * anymore, so we could be looking at a committed-dead entry.
    2136             :                  * Remember it so we can try to delete it later.
    2137             :                  */
    2138           0 :                 orphan_oids = lappend_oid(orphan_oids, relid);
    2139             :             }
    2140          14 :             continue;
    2141             :         }
    2142             : 
    2143             :         /* Fetch reloptions and the pgstat entry for this table */
    2144        2754 :         relopts = extract_autovac_opts(tuple, pg_class_desc);
    2145        2754 :         tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
    2146             :                                                   relid);
    2147             : 
    2148             :         /* Check if it needs vacuum or analyze */
    2149        2754 :         relation_needs_vacanalyze(relid, relopts, classForm, tabentry,
    2150             :                                   effective_multixact_freeze_max_age,
    2151             :                                   &dovacuum, &doanalyze, &wraparound);
    2152             : 
    2153             :         /* Relations that need work are added to table_oids */
    2154        2754 :         if (dovacuum || doanalyze)
    2155         200 :             table_oids = lappend_oid(table_oids, relid);
    2156             : 
    2157             :         /*
    2158             :          * Remember TOAST associations for the second pass.  Note: we must do
    2159             :          * this whether or not the table is going to be vacuumed, because we
    2160             :          * don't automatically vacuum toast tables along the parent table.
    2161             :          */
    2162        2754 :         if (OidIsValid(classForm->reltoastrelid))
    2163             :         {
    2164             :             av_relation *hentry;
    2165             :             bool        found;
    2166             : 
    2167        2708 :             hentry = hash_search(table_toast_map,
    2168        1354 :                                  &classForm->reltoastrelid,
    2169             :                                  HASH_ENTER, &found);
    2170             : 
    2171        1354 :             if (!found)
    2172             :             {
    2173             :                 /* hash_search already filled in the key */
    2174        1354 :                 hentry->ar_relid = relid;
    2175        1354 :                 hentry->ar_hasrelopts = false;
    2176        1354 :                 if (relopts != NULL)
    2177             :                 {
    2178          38 :                     hentry->ar_hasrelopts = true;
    2179          38 :                     memcpy(&hentry->ar_reloptions, relopts,
    2180             :                            sizeof(AutoVacOpts));
    2181             :                 }
    2182             :             }
    2183             :         }
    2184             :     }
    2185             : 
    2186          16 :     table_endscan(relScan);
    2187             : 
    2188             :     /* second pass: check TOAST tables */
    2189          16 :     ScanKeyInit(&key,
    2190             :                 Anum_pg_class_relkind,
    2191             :                 BTEqualStrategyNumber, F_CHAREQ,
    2192             :                 CharGetDatum(RELKIND_TOASTVALUE));
    2193             : 
    2194          16 :     relScan = table_beginscan_catalog(classRel, 1, &key);
    2195        1370 :     while ((tuple = heap_getnext(relScan, ForwardScanDirection)) != NULL)
    2196             :     {
    2197        1354 :         Form_pg_class classForm = (Form_pg_class) GETSTRUCT(tuple);
    2198             :         PgStat_StatTabEntry *tabentry;
    2199             :         Oid         relid;
    2200        1354 :         AutoVacOpts *relopts = NULL;
    2201             :         bool        dovacuum;
    2202             :         bool        doanalyze;
    2203             :         bool        wraparound;
    2204             : 
    2205             :         /*
    2206             :          * We cannot safely process other backends' temp tables, so skip 'em.
    2207             :          */
    2208        1354 :         if (classForm->relpersistence == RELPERSISTENCE_TEMP)
    2209           0 :             continue;
    2210             : 
    2211        1354 :         relid = classForm->oid;
    2212             : 
    2213             :         /*
    2214             :          * fetch reloptions -- if this toast table does not have them, try the
    2215             :          * main rel
    2216             :          */
    2217        1354 :         relopts = extract_autovac_opts(tuple, pg_class_desc);
    2218        1354 :         if (relopts == NULL)
    2219             :         {
    2220             :             av_relation *hentry;
    2221             :             bool        found;
    2222             : 
    2223        1352 :             hentry = hash_search(table_toast_map, &relid, HASH_FIND, &found);
    2224        1352 :             if (found && hentry->ar_hasrelopts)
    2225          36 :                 relopts = &hentry->ar_reloptions;
    2226             :         }
    2227             : 
    2228             :         /* Fetch the pgstat entry for this table */
    2229        1354 :         tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
    2230             :                                                   relid);
    2231             : 
    2232        1354 :         relation_needs_vacanalyze(relid, relopts, classForm, tabentry,
    2233             :                                   effective_multixact_freeze_max_age,
    2234             :                                   &dovacuum, &doanalyze, &wraparound);
    2235             : 
    2236             :         /* ignore analyze for toast tables */
    2237        1354 :         if (dovacuum)
    2238           2 :             table_oids = lappend_oid(table_oids, relid);
    2239             :     }
    2240             : 
    2241          16 :     table_endscan(relScan);
    2242          16 :     table_close(classRel, AccessShareLock);
    2243             : 
    2244             :     /*
    2245             :      * Recheck orphan temporary tables, and if they still seem orphaned, drop
    2246             :      * them.  We'll eat a transaction per dropped table, which might seem
    2247             :      * excessive, but we should only need to do anything as a result of a
    2248             :      * previous backend crash, so this should not happen often enough to
    2249             :      * justify "optimizing".  Using separate transactions ensures that we
    2250             :      * don't bloat the lock table if there are many temp tables to be dropped,
    2251             :      * and it ensures that we don't lose work if a deletion attempt fails.
    2252             :      */
    2253          16 :     foreach(cell, orphan_oids)
    2254             :     {
    2255           0 :         Oid         relid = lfirst_oid(cell);
    2256             :         Form_pg_class classForm;
    2257             :         ObjectAddress object;
    2258             : 
    2259             :         /*
    2260             :          * Check for user-requested abort.
    2261             :          */
    2262           0 :         CHECK_FOR_INTERRUPTS();
    2263             : 
    2264             :         /*
    2265             :          * Try to lock the table.  If we can't get the lock immediately,
    2266             :          * somebody else is using (or dropping) the table, so it's not our
    2267             :          * concern anymore.  Having the lock prevents race conditions below.
    2268             :          */
    2269           0 :         if (!ConditionalLockRelationOid(relid, AccessExclusiveLock))
    2270           0 :             continue;
    2271             : 
    2272             :         /*
    2273             :          * Re-fetch the pg_class tuple and re-check whether it still seems to
    2274             :          * be an orphaned temp table.  If it's not there or no longer the same
    2275             :          * relation, ignore it.
    2276             :          */
    2277           0 :         tuple = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relid));
    2278           0 :         if (!HeapTupleIsValid(tuple))
    2279             :         {
    2280             :             /* be sure to drop useless lock so we don't bloat lock table */
    2281           0 :             UnlockRelationOid(relid, AccessExclusiveLock);
    2282           0 :             continue;
    2283             :         }
    2284           0 :         classForm = (Form_pg_class) GETSTRUCT(tuple);
    2285             : 
    2286             :         /*
    2287             :          * Make all the same tests made in the loop above.  In event of OID
    2288             :          * counter wraparound, the pg_class entry we have now might be
    2289             :          * completely unrelated to the one we saw before.
    2290             :          */
    2291           0 :         if (!((classForm->relkind == RELKIND_RELATION ||
    2292           0 :                classForm->relkind == RELKIND_MATVIEW) &&
    2293           0 :               classForm->relpersistence == RELPERSISTENCE_TEMP))
    2294             :         {
    2295           0 :             UnlockRelationOid(relid, AccessExclusiveLock);
    2296           0 :             continue;
    2297             :         }
    2298             : 
    2299           0 :         if (checkTempNamespaceStatus(classForm->relnamespace) != TEMP_NAMESPACE_IDLE)
    2300             :         {
    2301           0 :             UnlockRelationOid(relid, AccessExclusiveLock);
    2302           0 :             continue;
    2303             :         }
    2304             : 
    2305             :         /* OK, let's delete it */
    2306           0 :         ereport(LOG,
    2307             :                 (errmsg("autovacuum: dropping orphan temp table \"%s.%s.%s\"",
    2308             :                         get_database_name(MyDatabaseId),
    2309             :                         get_namespace_name(classForm->relnamespace),
    2310             :                         NameStr(classForm->relname))));
    2311             : 
    2312           0 :         object.classId = RelationRelationId;
    2313           0 :         object.objectId = relid;
    2314           0 :         object.objectSubId = 0;
    2315           0 :         performDeletion(&object, DROP_CASCADE,
    2316             :                         PERFORM_DELETION_INTERNAL |
    2317             :                         PERFORM_DELETION_QUIETLY |
    2318             :                         PERFORM_DELETION_SKIP_EXTENSIONS);
    2319             : 
    2320             :         /*
    2321             :          * To commit the deletion, end current transaction and start a new
    2322             :          * one.  Note this also releases the lock we took.
    2323             :          */
    2324           0 :         CommitTransactionCommand();
    2325           0 :         StartTransactionCommand();
    2326             : 
    2327             :         /* StartTransactionCommand changed current memory context */
    2328           0 :         MemoryContextSwitchTo(AutovacMemCxt);
    2329             :     }
    2330             : 
    2331             :     /*
    2332             :      * Optionally, create a buffer access strategy object for VACUUM to use.
    2333             :      * We use the same BufferAccessStrategy object for all tables VACUUMed by
    2334             :      * this worker to prevent autovacuum from blowing out shared buffers.
    2335             :      *
    2336             :      * VacuumBufferUsageLimit being set to 0 results in
    2337             :      * GetAccessStrategyWithSize returning NULL, effectively meaning we can
    2338             :      * use up to all of shared buffers.
    2339             :      *
    2340             :      * If we later enter failsafe mode on any of the tables being vacuumed, we
    2341             :      * will cease use of the BufferAccessStrategy only for that table.
    2342             :      *
    2343             :      * XXX should we consider adding code to adjust the size of this if
    2344             :      * VacuumBufferUsageLimit changes?
    2345             :      */
    2346          16 :     bstrategy = GetAccessStrategyWithSize(BAS_VACUUM, VacuumBufferUsageLimit);
    2347             : 
    2348             :     /*
    2349             :      * create a memory context to act as fake PortalContext, so that the
    2350             :      * contexts created in the vacuum code are cleaned up for each table.
    2351             :      */
    2352          16 :     PortalContext = AllocSetContextCreate(AutovacMemCxt,
    2353             :                                           "Autovacuum Portal",
    2354             :                                           ALLOCSET_DEFAULT_SIZES);
    2355             : 
    2356             :     /*
    2357             :      * Perform operations on collected tables.
    2358             :      */
    2359         218 :     foreach(cell, table_oids)
    2360             :     {
    2361         202 :         Oid         relid = lfirst_oid(cell);
    2362             :         HeapTuple   classTup;
    2363             :         autovac_table *tab;
    2364             :         bool        isshared;
    2365             :         bool        skipit;
    2366             :         dlist_iter  iter;
    2367             : 
    2368         202 :         CHECK_FOR_INTERRUPTS();
    2369             : 
    2370             :         /*
    2371             :          * Check for config changes before processing each collected table.
    2372             :          */
    2373         202 :         if (ConfigReloadPending)
    2374             :         {
    2375           0 :             ConfigReloadPending = false;
    2376           0 :             ProcessConfigFile(PGC_SIGHUP);
    2377             : 
    2378             :             /*
    2379             :              * You might be tempted to bail out if we see autovacuum is now
    2380             :              * disabled.  Must resist that temptation -- this might be a
    2381             :              * for-wraparound emergency worker, in which case that would be
    2382             :              * entirely inappropriate.
    2383             :              */
    2384             :         }
    2385             : 
    2386             :         /*
    2387             :          * Find out whether the table is shared or not.  (It's slightly
    2388             :          * annoying to fetch the syscache entry just for this, but in typical
    2389             :          * cases it adds little cost because table_recheck_autovac would
    2390             :          * refetch the entry anyway.  We could buy that back by copying the
    2391             :          * tuple here and passing it to table_recheck_autovac, but that
    2392             :          * increases the odds of that function working with stale data.)
    2393             :          */
    2394         202 :         classTup = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
    2395         202 :         if (!HeapTupleIsValid(classTup))
    2396           0 :             continue;           /* somebody deleted the rel, forget it */
    2397         202 :         isshared = ((Form_pg_class) GETSTRUCT(classTup))->relisshared;
    2398         202 :         ReleaseSysCache(classTup);
    2399             : 
    2400             :         /*
    2401             :          * Hold schedule lock from here until we've claimed the table.  We
    2402             :          * also need the AutovacuumLock to walk the worker array, but that one
    2403             :          * can just be a shared lock.
    2404             :          */
    2405         202 :         LWLockAcquire(AutovacuumScheduleLock, LW_EXCLUSIVE);
    2406         202 :         LWLockAcquire(AutovacuumLock, LW_SHARED);
    2407             : 
    2408             :         /*
    2409             :          * Check whether the table is being vacuumed concurrently by another
    2410             :          * worker.
    2411             :          */
    2412         202 :         skipit = false;
    2413         404 :         dlist_foreach(iter, &AutoVacuumShmem->av_runningWorkers)
    2414             :         {
    2415         202 :             WorkerInfo  worker = dlist_container(WorkerInfoData, wi_links, iter.cur);
    2416             : 
    2417             :             /* ignore myself */
    2418         202 :             if (worker == MyWorkerInfo)
    2419         202 :                 continue;
    2420             : 
    2421             :             /* ignore workers in other databases (unless table is shared) */
    2422           0 :             if (!worker->wi_sharedrel && worker->wi_dboid != MyDatabaseId)
    2423           0 :                 continue;
    2424             : 
    2425           0 :             if (worker->wi_tableoid == relid)
    2426             :             {
    2427           0 :                 skipit = true;
    2428           0 :                 found_concurrent_worker = true;
    2429           0 :                 break;
    2430             :             }
    2431             :         }
    2432         202 :         LWLockRelease(AutovacuumLock);
    2433         202 :         if (skipit)
    2434             :         {
    2435           0 :             LWLockRelease(AutovacuumScheduleLock);
    2436           0 :             continue;
    2437             :         }
    2438             : 
    2439             :         /*
    2440             :          * Store the table's OID in shared memory before releasing the
    2441             :          * schedule lock, so that other workers don't try to vacuum it
    2442             :          * concurrently.  (We claim it here so as not to hold
    2443             :          * AutovacuumScheduleLock while rechecking the stats.)
    2444             :          */
    2445         202 :         MyWorkerInfo->wi_tableoid = relid;
    2446         202 :         MyWorkerInfo->wi_sharedrel = isshared;
    2447         202 :         LWLockRelease(AutovacuumScheduleLock);
    2448             : 
    2449             :         /*
    2450             :          * Check whether pgstat data still says we need to vacuum this table.
    2451             :          * It could have changed if something else processed the table while
    2452             :          * we weren't looking. This doesn't entirely close the race condition,
    2453             :          * but it is very small.
    2454             :          */
    2455         202 :         MemoryContextSwitchTo(AutovacMemCxt);
    2456         202 :         tab = table_recheck_autovac(relid, table_toast_map, pg_class_desc,
    2457             :                                     effective_multixact_freeze_max_age);
    2458         202 :         if (tab == NULL)
    2459             :         {
    2460             :             /* someone else vacuumed the table, or it went away */
    2461           0 :             LWLockAcquire(AutovacuumScheduleLock, LW_EXCLUSIVE);
    2462           0 :             MyWorkerInfo->wi_tableoid = InvalidOid;
    2463           0 :             MyWorkerInfo->wi_sharedrel = false;
    2464           0 :             LWLockRelease(AutovacuumScheduleLock);
    2465           0 :             continue;
    2466             :         }
    2467             : 
    2468             :         /*
    2469             :          * Save the cost-related storage parameter values in global variables
    2470             :          * for reference when updating vacuum_cost_delay and vacuum_cost_limit
    2471             :          * during vacuuming this table.
    2472             :          */
    2473         202 :         av_storage_param_cost_delay = tab->at_storage_param_vac_cost_delay;
    2474         202 :         av_storage_param_cost_limit = tab->at_storage_param_vac_cost_limit;
    2475             : 
    2476             :         /*
    2477             :          * We only expect this worker to ever set the flag, so don't bother
    2478             :          * checking the return value. We shouldn't have to retry.
    2479             :          */
    2480         202 :         if (tab->at_dobalance)
    2481         202 :             pg_atomic_test_set_flag(&MyWorkerInfo->wi_dobalance);
    2482             :         else
    2483           0 :             pg_atomic_clear_flag(&MyWorkerInfo->wi_dobalance);
    2484             : 
    2485         202 :         LWLockAcquire(AutovacuumLock, LW_SHARED);
    2486         202 :         autovac_recalculate_workers_for_balance();
    2487         202 :         LWLockRelease(AutovacuumLock);
    2488             : 
    2489             :         /*
    2490             :          * We wait until this point to update cost delay and cost limit
    2491             :          * values, even though we reloaded the configuration file above, so
    2492             :          * that we can take into account the cost-related storage parameters.
    2493             :          */
    2494         202 :         VacuumUpdateCosts();
    2495             : 
    2496             : 
    2497             :         /* clean up memory before each iteration */
    2498         202 :         MemoryContextReset(PortalContext);
    2499             : 
    2500             :         /*
    2501             :          * Save the relation name for a possible error message, to avoid a
    2502             :          * catalog lookup in case of an error.  If any of these return NULL,
    2503             :          * then the relation has been dropped since last we checked; skip it.
    2504             :          * Note: they must live in a long-lived memory context because we call
    2505             :          * vacuum and analyze in different transactions.
    2506             :          */
    2507             : 
    2508         202 :         tab->at_relname = get_rel_name(tab->at_relid);
    2509         202 :         tab->at_nspname = get_namespace_name(get_rel_namespace(tab->at_relid));
    2510         202 :         tab->at_datname = get_database_name(MyDatabaseId);
    2511         202 :         if (!tab->at_relname || !tab->at_nspname || !tab->at_datname)
    2512           0 :             goto deleted;
    2513             : 
    2514             :         /*
    2515             :          * We will abort vacuuming the current table if something errors out,
    2516             :          * and continue with the next one in schedule; in particular, this
    2517             :          * happens if we are interrupted with SIGINT.
    2518             :          */
    2519         202 :         PG_TRY();
    2520             :         {
    2521             :             /* Use PortalContext for any per-table allocations */
    2522         202 :             MemoryContextSwitchTo(PortalContext);
    2523             : 
    2524             :             /* have at it */
    2525         202 :             autovacuum_do_vac_analyze(tab, bstrategy);
    2526             : 
    2527             :             /*
    2528             :              * Clear a possible query-cancel signal, to avoid a late reaction
    2529             :              * to an automatically-sent signal because of vacuuming the
    2530             :              * current table (we're done with it, so it would make no sense to
    2531             :              * cancel at this point.)
    2532             :              */
    2533         202 :             QueryCancelPending = false;
    2534             :         }
    2535           0 :         PG_CATCH();
    2536             :         {
    2537             :             /*
    2538             :              * Abort the transaction, start a new one, and proceed with the
    2539             :              * next table in our list.
    2540             :              */
    2541           0 :             HOLD_INTERRUPTS();
    2542           0 :             if (tab->at_params.options & VACOPT_VACUUM)
    2543           0 :                 errcontext("automatic vacuum of table \"%s.%s.%s\"",
    2544             :                            tab->at_datname, tab->at_nspname, tab->at_relname);
    2545             :             else
    2546           0 :                 errcontext("automatic analyze of table \"%s.%s.%s\"",
    2547             :                            tab->at_datname, tab->at_nspname, tab->at_relname);
    2548           0 :             EmitErrorReport();
    2549             : 
    2550             :             /* this resets ProcGlobal->statusFlags[i] too */
    2551           0 :             AbortOutOfAnyTransaction();
    2552           0 :             FlushErrorState();
    2553           0 :             MemoryContextReset(PortalContext);
    2554             : 
    2555             :             /* restart our transaction for the following operations */
    2556           0 :             StartTransactionCommand();
    2557           0 :             RESUME_INTERRUPTS();
    2558             :         }
    2559         202 :         PG_END_TRY();
    2560             : 
    2561             :         /* Make sure we're back in AutovacMemCxt */
    2562         202 :         MemoryContextSwitchTo(AutovacMemCxt);
    2563             : 
    2564         202 :         did_vacuum = true;
    2565             : 
    2566             :         /* ProcGlobal->statusFlags[i] are reset at the next end of xact */
    2567             : 
    2568             :         /* be tidy */
    2569         202 : deleted:
    2570         202 :         if (tab->at_datname != NULL)
    2571         202 :             pfree(tab->at_datname);
    2572         202 :         if (tab->at_nspname != NULL)
    2573         202 :             pfree(tab->at_nspname);
    2574         202 :         if (tab->at_relname != NULL)
    2575         202 :             pfree(tab->at_relname);
    2576         202 :         pfree(tab);
    2577             : 
    2578             :         /*
    2579             :          * Remove my info from shared memory.  We set wi_dobalance on the
    2580             :          * assumption that we are more likely than not to vacuum a table with
    2581             :          * no cost-related storage parameters next, so we want to claim our
    2582             :          * share of I/O as soon as possible to avoid thrashing the global
    2583             :          * balance.
    2584             :          */
    2585         202 :         LWLockAcquire(AutovacuumScheduleLock, LW_EXCLUSIVE);
    2586         202 :         MyWorkerInfo->wi_tableoid = InvalidOid;
    2587         202 :         MyWorkerInfo->wi_sharedrel = false;
    2588         202 :         LWLockRelease(AutovacuumScheduleLock);
    2589         202 :         pg_atomic_test_set_flag(&MyWorkerInfo->wi_dobalance);
    2590             :     }
    2591             : 
    2592             :     /*
    2593             :      * Perform additional work items, as requested by backends.
    2594             :      */
    2595          16 :     LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    2596        4112 :     for (i = 0; i < NUM_WORKITEMS; i++)
    2597             :     {
    2598        4096 :         AutoVacuumWorkItem *workitem = &AutoVacuumShmem->av_workItems[i];
    2599             : 
    2600        4096 :         if (!workitem->avw_used)
    2601        4090 :             continue;
    2602           6 :         if (workitem->avw_active)
    2603           0 :             continue;
    2604           6 :         if (workitem->avw_database != MyDatabaseId)
    2605           0 :             continue;
    2606             : 
    2607             :         /* claim this one, and release lock while performing it */
    2608           6 :         workitem->avw_active = true;
    2609           6 :         LWLockRelease(AutovacuumLock);
    2610             : 
    2611           6 :         perform_work_item(workitem);
    2612             : 
    2613             :         /*
    2614             :          * Check for config changes before acquiring lock for further jobs.
    2615             :          */
    2616           6 :         CHECK_FOR_INTERRUPTS();
    2617           6 :         if (ConfigReloadPending)
    2618             :         {
    2619           0 :             ConfigReloadPending = false;
    2620           0 :             ProcessConfigFile(PGC_SIGHUP);
    2621           0 :             VacuumUpdateCosts();
    2622             :         }
    2623             : 
    2624           6 :         LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    2625             : 
    2626             :         /* and mark it done */
    2627           6 :         workitem->avw_active = false;
    2628           6 :         workitem->avw_used = false;
    2629             :     }
    2630          16 :     LWLockRelease(AutovacuumLock);
    2631             : 
    2632             :     /*
    2633             :      * We leak table_toast_map here (among other things), but since we're
    2634             :      * going away soon, it's not a problem.
    2635             :      */
    2636             : 
    2637             :     /*
    2638             :      * Update pg_database.datfrozenxid, and truncate pg_xact if possible. We
    2639             :      * only need to do this once, not after each table.
    2640             :      *
    2641             :      * Even if we didn't vacuum anything, it may still be important to do
    2642             :      * this, because one indirect effect of vac_update_datfrozenxid() is to
    2643             :      * update ShmemVariableCache->xidVacLimit.  That might need to be done
    2644             :      * even if we haven't vacuumed anything, because relations with older
    2645             :      * relfrozenxid values or other databases with older datfrozenxid values
    2646             :      * might have been dropped, allowing xidVacLimit to advance.
    2647             :      *
    2648             :      * However, it's also important not to do this blindly in all cases,
    2649             :      * because when autovacuum=off this will restart the autovacuum launcher.
    2650             :      * If we're not careful, an infinite loop can result, where workers find
    2651             :      * no work to do and restart the launcher, which starts another worker in
    2652             :      * the same database that finds no work to do.  To prevent that, we skip
    2653             :      * this if (1) we found no work to do and (2) we skipped at least one
    2654             :      * table due to concurrent autovacuum activity.  In that case, the other
    2655             :      * worker has already done it, or will do so when it finishes.
    2656             :      */
    2657          16 :     if (did_vacuum || !found_concurrent_worker)
    2658          16 :         vac_update_datfrozenxid();
    2659             : 
    2660             :     /* Finally close out the last transaction. */
    2661          16 :     CommitTransactionCommand();
    2662          16 : }
    2663             : 
    2664             : /*
    2665             :  * Execute a previously registered work item.
    2666             :  */
    2667             : static void
    2668           6 : perform_work_item(AutoVacuumWorkItem *workitem)
    2669             : {
    2670           6 :     char       *cur_datname = NULL;
    2671           6 :     char       *cur_nspname = NULL;
    2672           6 :     char       *cur_relname = NULL;
    2673             : 
    2674             :     /*
    2675             :      * Note we do not store table info in MyWorkerInfo, since this is not
    2676             :      * vacuuming proper.
    2677             :      */
    2678             : 
    2679             :     /*
    2680             :      * Save the relation name for a possible error message, to avoid a catalog
    2681             :      * lookup in case of an error.  If any of these return NULL, then the
    2682             :      * relation has been dropped since last we checked; skip it.
    2683             :      */
    2684             :     Assert(CurrentMemoryContext == AutovacMemCxt);
    2685             : 
    2686           6 :     cur_relname = get_rel_name(workitem->avw_relation);
    2687           6 :     cur_nspname = get_namespace_name(get_rel_namespace(workitem->avw_relation));
    2688           6 :     cur_datname = get_database_name(MyDatabaseId);
    2689           6 :     if (!cur_relname || !cur_nspname || !cur_datname)
    2690           0 :         goto deleted2;
    2691             : 
    2692           6 :     autovac_report_workitem(workitem, cur_nspname, cur_relname);
    2693             : 
    2694             :     /* clean up memory before each work item */
    2695           6 :     MemoryContextReset(PortalContext);
    2696             : 
    2697             :     /*
    2698             :      * We will abort the current work item if something errors out, and
    2699             :      * continue with the next one; in particular, this happens if we are
    2700             :      * interrupted with SIGINT.  Note that this means that the work item list
    2701             :      * can be lossy.
    2702             :      */
    2703           6 :     PG_TRY();
    2704             :     {
    2705             :         /* Use PortalContext for any per-work-item allocations */
    2706           6 :         MemoryContextSwitchTo(PortalContext);
    2707             : 
    2708             :         /*
    2709             :          * Have at it.  Functions called here are responsible for any required
    2710             :          * user switch and sandbox.
    2711             :          */
    2712           6 :         switch (workitem->avw_type)
    2713             :         {
    2714           6 :             case AVW_BRINSummarizeRange:
    2715           6 :                 DirectFunctionCall2(brin_summarize_range,
    2716             :                                     ObjectIdGetDatum(workitem->avw_relation),
    2717             :                                     Int64GetDatum((int64) workitem->avw_blockNumber));
    2718           6 :                 break;
    2719           0 :             default:
    2720           0 :                 elog(WARNING, "unrecognized work item found: type %d",
    2721             :                      workitem->avw_type);
    2722           0 :                 break;
    2723             :         }
    2724             : 
    2725             :         /*
    2726             :          * Clear a possible query-cancel signal, to avoid a late reaction to
    2727             :          * an automatically-sent signal because of vacuuming the current table
    2728             :          * (we're done with it, so it would make no sense to cancel at this
    2729             :          * point.)
    2730             :          */
    2731           6 :         QueryCancelPending = false;
    2732             :     }
    2733           0 :     PG_CATCH();
    2734             :     {
    2735             :         /*
    2736             :          * Abort the transaction, start a new one, and proceed with the next
    2737             :          * table in our list.
    2738             :          */
    2739           0 :         HOLD_INTERRUPTS();
    2740           0 :         errcontext("processing work entry for relation \"%s.%s.%s\"",
    2741             :                    cur_datname, cur_nspname, cur_relname);
    2742           0 :         EmitErrorReport();
    2743             : 
    2744             :         /* this resets ProcGlobal->statusFlags[i] too */
    2745           0 :         AbortOutOfAnyTransaction();
    2746           0 :         FlushErrorState();
    2747           0 :         MemoryContextReset(PortalContext);
    2748             : 
    2749             :         /* restart our transaction for the following operations */
    2750           0 :         StartTransactionCommand();
    2751           0 :         RESUME_INTERRUPTS();
    2752             :     }
    2753           6 :     PG_END_TRY();
    2754             : 
    2755             :     /* Make sure we're back in AutovacMemCxt */
    2756           6 :     MemoryContextSwitchTo(AutovacMemCxt);
    2757             : 
    2758             :     /* We intentionally do not set did_vacuum here */
    2759             : 
    2760             :     /* be tidy */
    2761           6 : deleted2:
    2762           6 :     if (cur_datname)
    2763           6 :         pfree(cur_datname);
    2764           6 :     if (cur_nspname)
    2765           6 :         pfree(cur_nspname);
    2766           6 :     if (cur_relname)
    2767           6 :         pfree(cur_relname);
    2768           6 : }
    2769             : 
    2770             : /*
    2771             :  * extract_autovac_opts
    2772             :  *
    2773             :  * Given a relation's pg_class tuple, return the AutoVacOpts portion of
    2774             :  * reloptions, if set; otherwise, return NULL.
    2775             :  *
    2776             :  * Note: callers do not have a relation lock on the table at this point,
    2777             :  * so the table could have been dropped, and its catalog rows gone, after
    2778             :  * we acquired the pg_class row.  If pg_class had a TOAST table, this would
    2779             :  * be a risk; fortunately, it doesn't.
    2780             :  */
    2781             : static AutoVacOpts *
    2782        4310 : extract_autovac_opts(HeapTuple tup, TupleDesc pg_class_desc)
    2783             : {
    2784             :     bytea      *relopts;
    2785             :     AutoVacOpts *av;
    2786             : 
    2787             :     Assert(((Form_pg_class) GETSTRUCT(tup))->relkind == RELKIND_RELATION ||
    2788             :            ((Form_pg_class) GETSTRUCT(tup))->relkind == RELKIND_MATVIEW ||
    2789             :            ((Form_pg_class) GETSTRUCT(tup))->relkind == RELKIND_TOASTVALUE);
    2790             : 
    2791        4310 :     relopts = extractRelOptions(tup, pg_class_desc, NULL);
    2792        4310 :     if (relopts == NULL)
    2793        4232 :         return NULL;
    2794             : 
    2795          78 :     av = palloc(sizeof(AutoVacOpts));
    2796          78 :     memcpy(av, &(((StdRdOptions *) relopts)->autovacuum), sizeof(AutoVacOpts));
    2797          78 :     pfree(relopts);
    2798             : 
    2799          78 :     return av;
    2800             : }
    2801             : 
    2802             : 
    2803             : /*
    2804             :  * table_recheck_autovac
    2805             :  *
    2806             :  * Recheck whether a table still needs vacuum or analyze.  Return value is a
    2807             :  * valid autovac_table pointer if it does, NULL otherwise.
    2808             :  *
    2809             :  * Note that the returned autovac_table does not have the name fields set.
    2810             :  */
    2811             : static autovac_table *
    2812         202 : table_recheck_autovac(Oid relid, HTAB *table_toast_map,
    2813             :                       TupleDesc pg_class_desc,
    2814             :                       int effective_multixact_freeze_max_age)
    2815             : {
    2816             :     Form_pg_class classForm;
    2817             :     HeapTuple   classTup;
    2818             :     bool        dovacuum;
    2819             :     bool        doanalyze;
    2820         202 :     autovac_table *tab = NULL;
    2821             :     bool        wraparound;
    2822             :     AutoVacOpts *avopts;
    2823             : 
    2824             :     /* fetch the relation's relcache entry */
    2825         202 :     classTup = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relid));
    2826         202 :     if (!HeapTupleIsValid(classTup))
    2827           0 :         return NULL;
    2828         202 :     classForm = (Form_pg_class) GETSTRUCT(classTup);
    2829             : 
    2830             :     /*
    2831             :      * Get the applicable reloptions.  If it is a TOAST table, try to get the
    2832             :      * main table reloptions if the toast table itself doesn't have.
    2833             :      */
    2834         202 :     avopts = extract_autovac_opts(classTup, pg_class_desc);
    2835         202 :     if (classForm->relkind == RELKIND_TOASTVALUE &&
    2836           2 :         avopts == NULL && table_toast_map != NULL)
    2837             :     {
    2838             :         av_relation *hentry;
    2839             :         bool        found;
    2840             : 
    2841           2 :         hentry = hash_search(table_toast_map, &relid, HASH_FIND, &found);
    2842           2 :         if (found && hentry->ar_hasrelopts)
    2843           0 :             avopts = &hentry->ar_reloptions;
    2844             :     }
    2845             : 
    2846         202 :     recheck_relation_needs_vacanalyze(relid, avopts, classForm,
    2847             :                                       effective_multixact_freeze_max_age,
    2848             :                                       &dovacuum, &doanalyze, &wraparound);
    2849             : 
    2850             :     /* OK, it needs something done */
    2851         202 :     if (doanalyze || dovacuum)
    2852             :     {
    2853             :         int         freeze_min_age;
    2854             :         int         freeze_table_age;
    2855             :         int         multixact_freeze_min_age;
    2856             :         int         multixact_freeze_table_age;
    2857             :         int         log_min_duration;
    2858             : 
    2859             :         /*
    2860             :          * Calculate the vacuum cost parameters and the freeze ages.  If there
    2861             :          * are options set in pg_class.reloptions, use them; in the case of a
    2862             :          * toast table, try the main table too.  Otherwise use the GUC
    2863             :          * defaults, autovacuum's own first and plain vacuum second.
    2864             :          */
    2865             : 
    2866             :         /* -1 in autovac setting means use log_autovacuum_min_duration */
    2867           6 :         log_min_duration = (avopts && avopts->log_min_duration >= 0)
    2868             :             ? avopts->log_min_duration
    2869         208 :             : Log_autovacuum_min_duration;
    2870             : 
    2871             :         /* these do not have autovacuum-specific settings */
    2872           6 :         freeze_min_age = (avopts && avopts->freeze_min_age >= 0)
    2873             :             ? avopts->freeze_min_age
    2874         208 :             : default_freeze_min_age;
    2875             : 
    2876           6 :         freeze_table_age = (avopts && avopts->freeze_table_age >= 0)
    2877             :             ? avopts->freeze_table_age
    2878         208 :             : default_freeze_table_age;
    2879             : 
    2880         208 :         multixact_freeze_min_age = (avopts &&
    2881           6 :                                     avopts->multixact_freeze_min_age >= 0)
    2882             :             ? avopts->multixact_freeze_min_age
    2883         208 :             : default_multixact_freeze_min_age;
    2884             : 
    2885         208 :         multixact_freeze_table_age = (avopts &&
    2886           6 :                                       avopts->multixact_freeze_table_age >= 0)
    2887             :             ? avopts->multixact_freeze_table_age
    2888         208 :             : default_multixact_freeze_table_age;
    2889             : 
    2890         202 :         tab = palloc(sizeof(autovac_table));
    2891         202 :         tab->at_relid = relid;
    2892         202 :         tab->at_sharedrel = classForm->relisshared;
    2893             : 
    2894             :         /*
    2895             :          * Select VACUUM options.  Note we don't say VACOPT_PROCESS_TOAST, so
    2896             :          * that vacuum() skips toast relations.  Also note we tell vacuum() to
    2897             :          * skip vac_update_datfrozenxid(); we'll do that separately.
    2898             :          */
    2899         202 :         tab->at_params.options =
    2900         202 :             (dovacuum ? (VACOPT_VACUUM |
    2901             :                          VACOPT_PROCESS_MAIN |
    2902         202 :                          VACOPT_SKIP_DATABASE_STATS) : 0) |
    2903         202 :             (doanalyze ? VACOPT_ANALYZE : 0) |
    2904         202 :             (!wraparound ? VACOPT_SKIP_LOCKED : 0);
    2905             : 
    2906             :         /*
    2907             :          * index_cleanup and truncate are unspecified at first in autovacuum.
    2908             :          * They will be filled in with usable values using their reloptions
    2909             :          * (or reloption defaults) later.
    2910             :          */
    2911         202 :         tab->at_params.index_cleanup = VACOPTVALUE_UNSPECIFIED;
    2912         202 :         tab->at_params.truncate = VACOPTVALUE_UNSPECIFIED;
    2913             :         /* As of now, we don't support parallel vacuum for autovacuum */
    2914         202 :         tab->at_params.nworkers = -1;
    2915         202 :         tab->at_params.freeze_min_age = freeze_min_age;
    2916         202 :         tab->at_params.freeze_table_age = freeze_table_age;
    2917         202 :         tab->at_params.multixact_freeze_min_age = multixact_freeze_min_age;
    2918         202 :         tab->at_params.multixact_freeze_table_age = multixact_freeze_table_age;
    2919         202 :         tab->at_params.is_wraparound = wraparound;
    2920         202 :         tab->at_params.log_min_duration = log_min_duration;
    2921         202 :         tab->at_storage_param_vac_cost_limit = avopts ?
    2922         202 :             avopts->vacuum_cost_limit : 0;
    2923         202 :         tab->at_storage_param_vac_cost_delay = avopts ?
    2924         202 :             avopts->vacuum_cost_delay : -1;
    2925         202 :         tab->at_relname = NULL;
    2926         202 :         tab->at_nspname = NULL;
    2927         202 :         tab->at_datname = NULL;
    2928             : 
    2929             :         /*
    2930             :          * If any of the cost delay parameters has been set individually for
    2931             :          * this table, disable the balancing algorithm.
    2932             :          */
    2933         202 :         tab->at_dobalance =
    2934         208 :             !(avopts && (avopts->vacuum_cost_limit > 0 ||
    2935           6 :                          avopts->vacuum_cost_delay >= 0));
    2936             :     }
    2937             : 
    2938         202 :     heap_freetuple(classTup);
    2939         202 :     return tab;
    2940             : }
    2941             : 
    2942             : /*
    2943             :  * recheck_relation_needs_vacanalyze
    2944             :  *
    2945             :  * Subroutine for table_recheck_autovac.
    2946             :  *
    2947             :  * Fetch the pgstat of a relation and recheck whether a relation
    2948             :  * needs to be vacuumed or analyzed.
    2949             :  */
    2950             : static void
    2951         202 : recheck_relation_needs_vacanalyze(Oid relid,
    2952             :                                   AutoVacOpts *avopts,
    2953             :                                   Form_pg_class classForm,
    2954             :                                   int effective_multixact_freeze_max_age,
    2955             :                                   bool *dovacuum,
    2956             :                                   bool *doanalyze,
    2957             :                                   bool *wraparound)
    2958             : {
    2959             :     PgStat_StatTabEntry *tabentry;
    2960             : 
    2961             :     /* fetch the pgstat table entry */
    2962         202 :     tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
    2963             :                                               relid);
    2964             : 
    2965         202 :     relation_needs_vacanalyze(relid, avopts, classForm, tabentry,
    2966             :                               effective_multixact_freeze_max_age,
    2967             :                               dovacuum, doanalyze, wraparound);
    2968             : 
    2969             :     /* ignore ANALYZE for toast tables */
    2970         202 :     if (classForm->relkind == RELKIND_TOASTVALUE)
    2971           2 :         *doanalyze = false;
    2972         202 : }
    2973             : 
    2974             : /*
    2975             :  * relation_needs_vacanalyze
    2976             :  *
    2977             :  * Check whether a relation needs to be vacuumed or analyzed; return each into
    2978             :  * "dovacuum" and "doanalyze", respectively.  Also return whether the vacuum is
    2979             :  * being forced because of Xid or multixact wraparound.
    2980             :  *
    2981             :  * relopts is a pointer to the AutoVacOpts options (either for itself in the
    2982             :  * case of a plain table, or for either itself or its parent table in the case
    2983             :  * of a TOAST table), NULL if none; tabentry is the pgstats entry, which can be
    2984             :  * NULL.
    2985             :  *
    2986             :  * A table needs to be vacuumed if the number of dead tuples exceeds a
    2987             :  * threshold.  This threshold is calculated as
    2988             :  *
    2989             :  * threshold = vac_base_thresh + vac_scale_factor * reltuples
    2990             :  *
    2991             :  * For analyze, the analysis done is that the number of tuples inserted,
    2992             :  * deleted and updated since the last analyze exceeds a threshold calculated
    2993             :  * in the same fashion as above.  Note that the cumulative stats system stores
    2994             :  * the number of tuples (both live and dead) that there were as of the last
    2995             :  * analyze.  This is asymmetric to the VACUUM case.
    2996             :  *
    2997             :  * We also force vacuum if the table's relfrozenxid is more than freeze_max_age
    2998             :  * transactions back, and if its relminmxid is more than
    2999             :  * multixact_freeze_max_age multixacts back.
    3000             :  *
    3001             :  * A table whose autovacuum_enabled option is false is
    3002             :  * automatically skipped (unless we have to vacuum it due to freeze_max_age).
    3003             :  * Thus autovacuum can be disabled for specific tables. Also, when the cumulative
    3004             :  * stats system does not have data about a table, it will be skipped.
    3005             :  *
    3006             :  * A table whose vac_base_thresh value is < 0 takes the base value from the
    3007             :  * autovacuum_vacuum_threshold GUC variable.  Similarly, a vac_scale_factor
    3008             :  * value < 0 is substituted with the value of
    3009             :  * autovacuum_vacuum_scale_factor GUC variable.  Ditto for analyze.
    3010             :  */
    3011             : static void
    3012        4310 : relation_needs_vacanalyze(Oid relid,
    3013             :                           AutoVacOpts *relopts,
    3014             :                           Form_pg_class classForm,
    3015             :                           PgStat_StatTabEntry *tabentry,
    3016             :                           int effective_multixact_freeze_max_age,
    3017             :  /* output params below */
    3018             :                           bool *dovacuum,
    3019             :                           bool *doanalyze,
    3020             :                           bool *wraparound)
    3021             : {
    3022             :     bool        force_vacuum;
    3023             :     bool        av_enabled;
    3024             :     float4      reltuples;      /* pg_class.reltuples */
    3025             : 
    3026             :     /* constants from reloptions or GUC variables */
    3027             :     int         vac_base_thresh,
    3028             :                 vac_ins_base_thresh,
    3029             :                 anl_base_thresh;
    3030             :     float4      vac_scale_factor,
    3031             :                 vac_ins_scale_factor,
    3032             :                 anl_scale_factor;
    3033             : 
    3034             :     /* thresholds calculated from above constants */
    3035             :     float4      vacthresh,
    3036             :                 vacinsthresh,
    3037             :                 anlthresh;
    3038             : 
    3039             :     /* number of vacuum (resp. analyze) tuples at this time */
    3040             :     float4      vactuples,
    3041             :                 instuples,
    3042             :                 anltuples;
    3043             : 
    3044             :     /* freeze parameters */
    3045             :     int         freeze_max_age;
    3046             :     int         multixact_freeze_max_age;
    3047             :     TransactionId xidForceLimit;
    3048             :     MultiXactId multiForceLimit;
    3049             : 
    3050             :     Assert(classForm != NULL);
    3051             :     Assert(OidIsValid(relid));
    3052             : 
    3053             :     /*
    3054             :      * Determine vacuum/analyze equation parameters.  We have two possible
    3055             :      * sources: the passed reloptions (which could be a main table or a toast
    3056             :      * table), or the autovacuum GUC variables.
    3057             :      */
    3058             : 
    3059             :     /* -1 in autovac setting means use plain vacuum_scale_factor */
    3060         114 :     vac_scale_factor = (relopts && relopts->vacuum_scale_factor >= 0)
    3061           0 :         ? relopts->vacuum_scale_factor
    3062        4424 :         : autovacuum_vac_scale;
    3063             : 
    3064         114 :     vac_base_thresh = (relopts && relopts->vacuum_threshold >= 0)
    3065             :         ? relopts->vacuum_threshold
    3066        4424 :         : autovacuum_vac_thresh;
    3067             : 
    3068         114 :     vac_ins_scale_factor = (relopts && relopts->vacuum_ins_scale_factor >= 0)
    3069           0 :         ? relopts->vacuum_ins_scale_factor
    3070        4424 :         : autovacuum_vac_ins_scale;
    3071             : 
    3072             :     /* -1 is used to disable insert vacuums */
    3073         114 :     vac_ins_base_thresh = (relopts && relopts->vacuum_ins_threshold >= -1)
    3074             :         ? relopts->vacuum_ins_threshold
    3075        4424 :         : autovacuum_vac_ins_thresh;
    3076             : 
    3077         114 :     anl_scale_factor = (relopts && relopts->analyze_scale_factor >= 0)
    3078           0 :         ? relopts->analyze_scale_factor
    3079        4424 :         : autovacuum_anl_scale;
    3080             : 
    3081         114 :     anl_base_thresh = (relopts && relopts->analyze_threshold >= 0)
    3082             :         ? relopts->analyze_threshold
    3083        4424 :         : autovacuum_anl_thresh;
    3084             : 
    3085         114 :     freeze_max_age = (relopts && relopts->freeze_max_age >= 0)
    3086           0 :         ? Min(relopts->freeze_max_age, autovacuum_freeze_max_age)
    3087        4424 :         : autovacuum_freeze_max_age;
    3088             : 
    3089         114 :     multixact_freeze_max_age = (relopts && relopts->multixact_freeze_max_age >= 0)
    3090           0 :         ? Min(relopts->multixact_freeze_max_age, effective_multixact_freeze_max_age)
    3091        4424 :         : effective_multixact_freeze_max_age;
    3092             : 
    3093        4310 :     av_enabled = (relopts ? relopts->enabled : true);
    3094             : 
    3095             :     /* Force vacuum if table is at risk of wraparound */
    3096        4310 :     xidForceLimit = recentXid - freeze_max_age;
    3097        4310 :     if (xidForceLimit < FirstNormalTransactionId)
    3098           0 :         xidForceLimit -= FirstNormalTransactionId;
    3099        8620 :     force_vacuum = (TransactionIdIsNormal(classForm->relfrozenxid) &&
    3100        4310 :                     TransactionIdPrecedes(classForm->relfrozenxid,
    3101             :                                           xidForceLimit));
    3102        4310 :     if (!force_vacuum)
    3103             :     {
    3104        4310 :         multiForceLimit = recentMulti - multixact_freeze_max_age;
    3105        4310 :         if (multiForceLimit < FirstMultiXactId)
    3106           0 :             multiForceLimit -= FirstMultiXactId;
    3107        8620 :         force_vacuum = MultiXactIdIsValid(classForm->relminmxid) &&
    3108        4310 :             MultiXactIdPrecedes(classForm->relminmxid, multiForceLimit);
    3109             :     }
    3110        4310 :     *wraparound = force_vacuum;
    3111             : 
    3112             :     /* User disabled it in pg_class.reloptions?  (But ignore if at risk) */
    3113        4310 :     if (!av_enabled && !force_vacuum)
    3114             :     {
    3115          78 :         *doanalyze = false;
    3116          78 :         *dovacuum = false;
    3117          78 :         return;
    3118             :     }
    3119             : 
    3120             :     /*
    3121             :      * If we found stats for the table, and autovacuum is currently enabled,
    3122             :      * make a threshold-based decision whether to vacuum and/or analyze.  If
    3123             :      * autovacuum is currently disabled, we must be here for anti-wraparound
    3124             :      * vacuuming only, so don't vacuum (or analyze) anything that's not being
    3125             :      * forced.
    3126             :      */
    3127        4232 :     if (PointerIsValid(tabentry) && AutoVacuumingActive())
    3128             :     {
    3129        3368 :         reltuples = classForm->reltuples;
    3130        3368 :         vactuples = tabentry->dead_tuples;
    3131        3368 :         instuples = tabentry->ins_since_vacuum;
    3132        3368 :         anltuples = tabentry->mod_since_analyze;
    3133             : 
    3134             :         /* If the table hasn't yet been vacuumed, take reltuples as zero */
    3135        3368 :         if (reltuples < 0)
    3136        1140 :             reltuples = 0;
    3137             : 
    3138        3368 :         vacthresh = (float4) vac_base_thresh + vac_scale_factor * reltuples;
    3139        3368 :         vacinsthresh = (float4) vac_ins_base_thresh + vac_ins_scale_factor * reltuples;
    3140        3368 :         anlthresh = (float4) anl_base_thresh + anl_scale_factor * reltuples;
    3141             : 
    3142             :         /*
    3143             :          * Note that we don't need to take special consideration for stat
    3144             :          * reset, because if that happens, the last vacuum and analyze counts
    3145             :          * will be reset too.
    3146             :          */
    3147        3368 :         if (vac_ins_base_thresh >= 0)
    3148        3368 :             elog(DEBUG3, "%s: vac: %.0f (threshold %.0f), ins: %.0f (threshold %.0f), anl: %.0f (threshold %.0f)",
    3149             :                  NameStr(classForm->relname),
    3150             :                  vactuples, vacthresh, instuples, vacinsthresh, anltuples, anlthresh);
    3151             :         else
    3152           0 :             elog(DEBUG3, "%s: vac: %.0f (threshold %.0f), ins: (disabled), anl: %.0f (threshold %.0f)",
    3153             :                  NameStr(classForm->relname),
    3154             :                  vactuples, vacthresh, anltuples, anlthresh);
    3155             : 
    3156             :         /* Determine if this table needs vacuum or analyze. */
    3157        6592 :         *dovacuum = force_vacuum || (vactuples > vacthresh) ||
    3158        3224 :             (vac_ins_base_thresh >= 0 && instuples > vacinsthresh);
    3159        3368 :         *doanalyze = (anltuples > anlthresh);
    3160             :     }
    3161             :     else
    3162             :     {
    3163             :         /*
    3164             :          * Skip a table not found in stat hash, unless we have to force vacuum
    3165             :          * for anti-wrap purposes.  If it's not acted upon, there's no need to
    3166             :          * vacuum it.
    3167             :          */
    3168         864 :         *dovacuum = force_vacuum;
    3169         864 :         *doanalyze = false;
    3170             :     }
    3171             : 
    3172             :     /* ANALYZE refuses to work with pg_statistic */
    3173        4232 :     if (relid == StatisticRelationId)
    3174          18 :         *doanalyze = false;
    3175             : }
    3176             : 
    3177             : /*
    3178             :  * autovacuum_do_vac_analyze
    3179             :  *      Vacuum and/or analyze the specified table
    3180             :  *
    3181             :  * We expect the caller to have switched into a memory context that won't
    3182             :  * disappear at transaction commit.
    3183             :  */
    3184             : static void
    3185         202 : autovacuum_do_vac_analyze(autovac_table *tab, BufferAccessStrategy bstrategy)
    3186             : {
    3187             :     RangeVar   *rangevar;
    3188             :     VacuumRelation *rel;
    3189             :     List       *rel_list;
    3190             :     MemoryContext vac_context;
    3191             : 
    3192             :     /* Let pgstat know what we're doing */
    3193         202 :     autovac_report_activity(tab);
    3194             : 
    3195             :     /* Set up one VacuumRelation target, identified by OID, for vacuum() */
    3196         202 :     rangevar = makeRangeVar(tab->at_nspname, tab->at_relname, -1);
    3197         202 :     rel = makeVacuumRelation(rangevar, tab->at_relid, NIL);
    3198         202 :     rel_list = list_make1(rel);
    3199             : 
    3200         202 :     vac_context = AllocSetContextCreate(CurrentMemoryContext,
    3201             :                                         "Vacuum",
    3202             :                                         ALLOCSET_DEFAULT_SIZES);
    3203             : 
    3204         202 :     vacuum(rel_list, &tab->at_params, bstrategy, vac_context, true);
    3205             : 
    3206         202 :     MemoryContextDelete(vac_context);
    3207         202 : }
    3208             : 
    3209             : /*
    3210             :  * autovac_report_activity
    3211             :  *      Report to pgstat what autovacuum is doing
    3212             :  *
    3213             :  * We send a SQL string corresponding to what the user would see if the
    3214             :  * equivalent command was to be issued manually.
    3215             :  *
    3216             :  * Note we assume that we are going to report the next command as soon as we're
    3217             :  * done with the current one, and exit right after the last one, so we don't
    3218             :  * bother to report "<IDLE>" or some such.
    3219             :  */
    3220             : static void
    3221         202 : autovac_report_activity(autovac_table *tab)
    3222             : {
    3223             : #define MAX_AUTOVAC_ACTIV_LEN (NAMEDATALEN * 2 + 56)
    3224             :     char        activity[MAX_AUTOVAC_ACTIV_LEN];
    3225             :     int         len;
    3226             : 
    3227             :     /* Report the command and possible options */
    3228         202 :     if (tab->at_params.options & VACOPT_VACUUM)
    3229         104 :         snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
    3230             :                  "autovacuum: VACUUM%s",
    3231         104 :                  tab->at_params.options & VACOPT_ANALYZE ? " ANALYZE" : "");
    3232             :     else
    3233          98 :         snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
    3234             :                  "autovacuum: ANALYZE");
    3235             : 
    3236             :     /*
    3237             :      * Report the qualified name of the relation.
    3238             :      */
    3239         202 :     len = strlen(activity);
    3240             : 
    3241         202 :     snprintf(activity + len, MAX_AUTOVAC_ACTIV_LEN - len,
    3242             :              " %s.%s%s", tab->at_nspname, tab->at_relname,
    3243         202 :              tab->at_params.is_wraparound ? " (to prevent wraparound)" : "");
    3244             : 
    3245             :     /* Set statement_timestamp() to current time for pg_stat_activity */
    3246         202 :     SetCurrentStatementStartTimestamp();
    3247             : 
    3248         202 :     pgstat_report_activity(STATE_RUNNING, activity);
    3249         202 : }
    3250             : 
    3251             : /*
    3252             :  * autovac_report_workitem
    3253             :  *      Report to pgstat that autovacuum is processing a work item
    3254             :  */
    3255             : static void
    3256           6 : autovac_report_workitem(AutoVacuumWorkItem *workitem,
    3257             :                         const char *nspname, const char *relname)
    3258             : {
    3259             :     char        activity[MAX_AUTOVAC_ACTIV_LEN + 12 + 2];
    3260             :     char        blk[12 + 2];
    3261             :     int         len;
    3262             : 
    3263           6 :     switch (workitem->avw_type)
    3264             :     {
    3265           6 :         case AVW_BRINSummarizeRange:
    3266           6 :             snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
    3267             :                      "autovacuum: BRIN summarize");
    3268           6 :             break;
    3269             :     }
    3270             : 
    3271             :     /*
    3272             :      * Report the qualified name of the relation, and the block number if any
    3273             :      */
    3274           6 :     len = strlen(activity);
    3275             : 
    3276           6 :     if (BlockNumberIsValid(workitem->avw_blockNumber))
    3277           6 :         snprintf(blk, sizeof(blk), " %u", workitem->avw_blockNumber);
    3278             :     else
    3279           0 :         blk[0] = '\0';
    3280             : 
    3281           6 :     snprintf(activity + len, MAX_AUTOVAC_ACTIV_LEN - len,
    3282             :              " %s.%s%s", nspname, relname, blk);
    3283             : 
    3284             :     /* Set statement_timestamp() to current time for pg_stat_activity */
    3285           6 :     SetCurrentStatementStartTimestamp();
    3286             : 
    3287           6 :     pgstat_report_activity(STATE_RUNNING, activity);
    3288           6 : }
    3289             : 
    3290             : /*
    3291             :  * AutoVacuumingActive
    3292             :  *      Check GUC vars and report whether the autovacuum process should be
    3293             :  *      running.
    3294             :  */
    3295             : bool
    3296       14228 : AutoVacuumingActive(void)
    3297             : {
    3298       14228 :     if (!autovacuum_start_daemon || !pgstat_track_counts)
    3299        3350 :         return false;
    3300       10878 :     return true;
    3301             : }
    3302             : 
    3303             : /*
    3304             :  * Request one work item to the next autovacuum run processing our database.
    3305             :  * Return false if the request can't be recorded.
    3306             :  */
    3307             : bool
    3308           6 : AutoVacuumRequestWork(AutoVacuumWorkItemType type, Oid relationId,
    3309             :                       BlockNumber blkno)
    3310             : {
    3311             :     int         i;
    3312           6 :     bool        result = false;
    3313             : 
    3314           6 :     LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    3315             : 
    3316             :     /*
    3317             :      * Locate an unused work item and fill it with the given data.
    3318             :      */
    3319          12 :     for (i = 0; i < NUM_WORKITEMS; i++)
    3320             :     {
    3321          12 :         AutoVacuumWorkItem *workitem = &AutoVacuumShmem->av_workItems[i];
    3322             : 
    3323          12 :         if (workitem->avw_used)
    3324           6 :             continue;
    3325             : 
    3326           6 :         workitem->avw_used = true;
    3327           6 :         workitem->avw_active = false;
    3328           6 :         workitem->avw_type = type;
    3329           6 :         workitem->avw_database = MyDatabaseId;
    3330           6 :         workitem->avw_relation = relationId;
    3331           6 :         workitem->avw_blockNumber = blkno;
    3332           6 :         result = true;
    3333             : 
    3334             :         /* done */
    3335           6 :         break;
    3336             :     }
    3337             : 
    3338           6 :     LWLockRelease(AutovacuumLock);
    3339             : 
    3340           6 :     return result;
    3341             : }
    3342             : 
    3343             : /*
    3344             :  * autovac_init
    3345             :  *      This is called at postmaster initialization.
    3346             :  *
    3347             :  * All we do here is annoy the user if he got it wrong.
    3348             :  */
    3349             : void
    3350        1280 : autovac_init(void)
    3351             : {
    3352        1280 :     if (autovacuum_start_daemon && !pgstat_track_counts)
    3353           0 :         ereport(WARNING,
    3354             :                 (errmsg("autovacuum not started because of misconfiguration"),
    3355             :                  errhint("Enable the \"track_counts\" option.")));
    3356        1280 : }
    3357             : 
    3358             : /*
    3359             :  * IsAutoVacuum functions
    3360             :  *      Return whether this is either a launcher autovacuum process or a worker
    3361             :  *      process.
    3362             :  */
    3363             : bool
    3364       96046 : IsAutoVacuumLauncherProcess(void)
    3365             : {
    3366       96046 :     return am_autovacuum_launcher;
    3367             : }
    3368             : 
    3369             : bool
    3370      178500 : IsAutoVacuumWorkerProcess(void)
    3371             : {
    3372      178500 :     return am_autovacuum_worker;
    3373             : }
    3374             : 
    3375             : 
    3376             : /*
    3377             :  * AutoVacuumShmemSize
    3378             :  *      Compute space needed for autovacuum-related shared memory
    3379             :  */
    3380             : Size
    3381        4496 : AutoVacuumShmemSize(void)
    3382             : {
    3383             :     Size        size;
    3384             : 
    3385             :     /*
    3386             :      * Need the fixed struct and the array of WorkerInfoData.
    3387             :      */
    3388        4496 :     size = sizeof(AutoVacuumShmemStruct);
    3389        4496 :     size = MAXALIGN(size);
    3390        4496 :     size = add_size(size, mul_size(autovacuum_max_workers,
    3391             :                                    sizeof(WorkerInfoData)));
    3392        4496 :     return size;
    3393             : }
    3394             : 
    3395             : /*
    3396             :  * AutoVacuumShmemInit
    3397             :  *      Allocate and initialize autovacuum-related shared memory
    3398             :  */
    3399             : void
    3400        1562 : AutoVacuumShmemInit(void)
    3401             : {
    3402             :     bool        found;
    3403             : 
    3404        1562 :     AutoVacuumShmem = (AutoVacuumShmemStruct *)
    3405        1562 :         ShmemInitStruct("AutoVacuum Data",
    3406             :                         AutoVacuumShmemSize(),
    3407             :                         &found);
    3408             : 
    3409        1562 :     if (!IsUnderPostmaster)
    3410             :     {
    3411             :         WorkerInfo  worker;
    3412             :         int         i;
    3413             : 
    3414             :         Assert(!found);
    3415             : 
    3416        1562 :         AutoVacuumShmem->av_launcherpid = 0;
    3417        1562 :         dlist_init(&AutoVacuumShmem->av_freeWorkers);
    3418        1562 :         dlist_init(&AutoVacuumShmem->av_runningWorkers);
    3419        1562 :         AutoVacuumShmem->av_startingWorker = NULL;
    3420        1562 :         memset(AutoVacuumShmem->av_workItems, 0,
    3421             :                sizeof(AutoVacuumWorkItem) * NUM_WORKITEMS);
    3422             : 
    3423        1562 :         worker = (WorkerInfo) ((char *) AutoVacuumShmem +
    3424             :                                MAXALIGN(sizeof(AutoVacuumShmemStruct)));
    3425             : 
    3426             :         /* initialize the WorkerInfo free list */
    3427        6248 :         for (i = 0; i < autovacuum_max_workers; i++)
    3428             :         {
    3429        4686 :             dlist_push_head(&AutoVacuumShmem->av_freeWorkers,
    3430        4686 :                             &worker[i].wi_links);
    3431        4686 :             pg_atomic_init_flag(&worker[i].wi_dobalance);
    3432             :         }
    3433             : 
    3434        1562 :         pg_atomic_init_u32(&AutoVacuumShmem->av_nworkersForBalance, 0);
    3435             : 
    3436             :     }
    3437             :     else
    3438             :         Assert(found);
    3439        1562 : }
    3440             : 
    3441             : /*
    3442             :  * GUC check_hook for autovacuum_work_mem
    3443             :  */
    3444             : bool
    3445        1628 : check_autovacuum_work_mem(int *newval, void **extra, GucSource source)
    3446             : {
    3447             :     /*
    3448             :      * -1 indicates fallback.
    3449             :      *
    3450             :      * If we haven't yet changed the boot_val default of -1, just let it be.
    3451             :      * Autovacuum will look to maintenance_work_mem instead.
    3452             :      */
    3453        1628 :     if (*newval == -1)
    3454        1624 :         return true;
    3455             : 
    3456             :     /*
    3457             :      * We clamp manually-set values to at least 1MB.  Since
    3458             :      * maintenance_work_mem is always set to at least this value, do the same
    3459             :      * here.
    3460             :      */
    3461           4 :     if (*newval < 1024)
    3462           4 :         *newval = 1024;
    3463             : 
    3464           4 :     return true;
    3465             : }

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