LCOV - code coverage report
Current view: top level - src/backend/postmaster - autovacuum.c (source / functions) Hit Total Coverage
Test: PostgreSQL 16beta1 Lines: 761 950 80.1 %
Date: 2023-05-31 04:12:22 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             : 
     390             : /*
     391             :  * We need this set from the outside, before InitProcess is called
     392             :  */
     393             : void
     394             : AutovacuumLauncherIAm(void)
     395             : {
     396             :     am_autovacuum_launcher = true;
     397             : }
     398             : #endif
     399             : 
     400             : /*
     401             :  * Main entry point for autovacuum launcher process, to be called from the
     402             :  * postmaster.
     403             :  */
     404             : int
     405         976 : StartAutoVacLauncher(void)
     406             : {
     407             :     pid_t       AutoVacPID;
     408             : 
     409             : #ifdef EXEC_BACKEND
     410             :     switch ((AutoVacPID = avlauncher_forkexec()))
     411             : #else
     412         976 :     switch ((AutoVacPID = fork_process()))
     413             : #endif
     414             :     {
     415           0 :         case -1:
     416           0 :             ereport(LOG,
     417             :                     (errmsg("could not fork autovacuum launcher process: %m")));
     418           0 :             return 0;
     419             : 
     420             : #ifndef EXEC_BACKEND
     421         598 :         case 0:
     422             :             /* in postmaster child ... */
     423         598 :             InitPostmasterChild();
     424             : 
     425             :             /* Close the postmaster's sockets */
     426         598 :             ClosePostmasterPorts(false);
     427             : 
     428         598 :             AutoVacLauncherMain(0, NULL);
     429             :             break;
     430             : #endif
     431         976 :         default:
     432         976 :             return (int) AutoVacPID;
     433             :     }
     434             : 
     435             :     /* shouldn't get here */
     436             :     return 0;
     437             : }
     438             : 
     439             : /*
     440             :  * Main loop for the autovacuum launcher process.
     441             :  */
     442             : NON_EXEC_STATIC void
     443         598 : AutoVacLauncherMain(int argc, char *argv[])
     444             : {
     445             :     sigjmp_buf  local_sigjmp_buf;
     446             : 
     447         598 :     am_autovacuum_launcher = true;
     448             : 
     449         598 :     MyBackendType = B_AUTOVAC_LAUNCHER;
     450         598 :     init_ps_display(NULL);
     451             : 
     452         598 :     ereport(DEBUG1,
     453             :             (errmsg_internal("autovacuum launcher started")));
     454             : 
     455         598 :     if (PostAuthDelay)
     456           0 :         pg_usleep(PostAuthDelay * 1000000L);
     457             : 
     458         598 :     SetProcessingMode(InitProcessing);
     459             : 
     460             :     /*
     461             :      * Set up signal handlers.  We operate on databases much like a regular
     462             :      * backend, so we use the same signal handling.  See equivalent code in
     463             :      * tcop/postgres.c.
     464             :      */
     465         598 :     pqsignal(SIGHUP, SignalHandlerForConfigReload);
     466         598 :     pqsignal(SIGINT, StatementCancelHandler);
     467         598 :     pqsignal(SIGTERM, SignalHandlerForShutdownRequest);
     468             :     /* SIGQUIT handler was already set up by InitPostmasterChild */
     469             : 
     470         598 :     InitializeTimeouts();       /* establishes SIGALRM handler */
     471             : 
     472         598 :     pqsignal(SIGPIPE, SIG_IGN);
     473         598 :     pqsignal(SIGUSR1, procsignal_sigusr1_handler);
     474         598 :     pqsignal(SIGUSR2, avl_sigusr2_handler);
     475         598 :     pqsignal(SIGFPE, FloatExceptionHandler);
     476         598 :     pqsignal(SIGCHLD, SIG_DFL);
     477             : 
     478             :     /*
     479             :      * Create a per-backend PGPROC struct in shared memory, except in the
     480             :      * EXEC_BACKEND case where this was done in SubPostmasterMain. We must do
     481             :      * this before we can use LWLocks (and in the EXEC_BACKEND case we already
     482             :      * had to do some stuff with LWLocks).
     483             :      */
     484             : #ifndef EXEC_BACKEND
     485         598 :     InitProcess();
     486             : #endif
     487             : 
     488             :     /* Early initialization */
     489         598 :     BaseInit();
     490             : 
     491         598 :     InitPostgres(NULL, InvalidOid, NULL, InvalidOid, false, false, NULL);
     492             : 
     493         598 :     SetProcessingMode(NormalProcessing);
     494             : 
     495             :     /*
     496             :      * Create a memory context that we will do all our work in.  We do this so
     497             :      * that we can reset the context during error recovery and thereby avoid
     498             :      * possible memory leaks.
     499             :      */
     500         598 :     AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,
     501             :                                           "Autovacuum Launcher",
     502             :                                           ALLOCSET_DEFAULT_SIZES);
     503         598 :     MemoryContextSwitchTo(AutovacMemCxt);
     504             : 
     505             :     /*
     506             :      * If an exception is encountered, processing resumes here.
     507             :      *
     508             :      * This code is a stripped down version of PostgresMain error recovery.
     509             :      *
     510             :      * Note that we use sigsetjmp(..., 1), so that the prevailing signal mask
     511             :      * (to wit, BlockSig) will be restored when longjmp'ing to here.  Thus,
     512             :      * signals other than SIGQUIT will be blocked until we complete error
     513             :      * recovery.  It might seem that this policy makes the HOLD_INTERRUPTS()
     514             :      * call redundant, but it is not since InterruptPending might be set
     515             :      * already.
     516             :      */
     517         598 :     if (sigsetjmp(local_sigjmp_buf, 1) != 0)
     518             :     {
     519             :         /* since not using PG_TRY, must reset error stack by hand */
     520           0 :         error_context_stack = NULL;
     521             : 
     522             :         /* Prevents interrupts while cleaning up */
     523           0 :         HOLD_INTERRUPTS();
     524             : 
     525             :         /* Forget any pending QueryCancel or timeout request */
     526           0 :         disable_all_timeouts(false);
     527           0 :         QueryCancelPending = false; /* second to avoid race condition */
     528             : 
     529             :         /* Report the error to the server log */
     530           0 :         EmitErrorReport();
     531             : 
     532             :         /* Abort the current transaction in order to recover */
     533           0 :         AbortCurrentTransaction();
     534             : 
     535             :         /*
     536             :          * Release any other resources, for the case where we were not in a
     537             :          * transaction.
     538             :          */
     539           0 :         LWLockReleaseAll();
     540           0 :         pgstat_report_wait_end();
     541           0 :         UnlockBuffers();
     542             :         /* this is probably dead code, but let's be safe: */
     543           0 :         if (AuxProcessResourceOwner)
     544           0 :             ReleaseAuxProcessResources(false);
     545           0 :         AtEOXact_Buffers(false);
     546           0 :         AtEOXact_SMgr();
     547           0 :         AtEOXact_Files(false);
     548           0 :         AtEOXact_HashTables(false);
     549             : 
     550             :         /*
     551             :          * Now return to normal top-level context and clear ErrorContext for
     552             :          * next time.
     553             :          */
     554           0 :         MemoryContextSwitchTo(AutovacMemCxt);
     555           0 :         FlushErrorState();
     556             : 
     557             :         /* Flush any leaked data in the top-level context */
     558           0 :         MemoryContextResetAndDeleteChildren(AutovacMemCxt);
     559             : 
     560             :         /* don't leave dangling pointers to freed memory */
     561           0 :         DatabaseListCxt = NULL;
     562           0 :         dlist_init(&DatabaseList);
     563             : 
     564             :         /* Now we can allow interrupts again */
     565           0 :         RESUME_INTERRUPTS();
     566             : 
     567             :         /* if in shutdown mode, no need for anything further; just go away */
     568           0 :         if (ShutdownRequestPending)
     569           0 :             AutoVacLauncherShutdown();
     570             : 
     571             :         /*
     572             :          * Sleep at least 1 second after any error.  We don't want to be
     573             :          * filling the error logs as fast as we can.
     574             :          */
     575           0 :         pg_usleep(1000000L);
     576             :     }
     577             : 
     578             :     /* We can now handle ereport(ERROR) */
     579         598 :     PG_exception_stack = &local_sigjmp_buf;
     580             : 
     581             :     /* must unblock signals before calling rebuild_database_list */
     582         598 :     sigprocmask(SIG_SETMASK, &UnBlockSig, NULL);
     583             : 
     584             :     /*
     585             :      * Set always-secure search path.  Launcher doesn't connect to a database,
     586             :      * so this has no effect.
     587             :      */
     588         598 :     SetConfigOption("search_path", "", PGC_SUSET, PGC_S_OVERRIDE);
     589             : 
     590             :     /*
     591             :      * Force zero_damaged_pages OFF in the autovac process, even if it is set
     592             :      * in postgresql.conf.  We don't really want such a dangerous option being
     593             :      * applied non-interactively.
     594             :      */
     595         598 :     SetConfigOption("zero_damaged_pages", "false", PGC_SUSET, PGC_S_OVERRIDE);
     596             : 
     597             :     /*
     598             :      * Force settable timeouts off to avoid letting these settings prevent
     599             :      * regular maintenance from being executed.
     600             :      */
     601         598 :     SetConfigOption("statement_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
     602         598 :     SetConfigOption("lock_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
     603         598 :     SetConfigOption("idle_in_transaction_session_timeout", "0",
     604             :                     PGC_SUSET, PGC_S_OVERRIDE);
     605             : 
     606             :     /*
     607             :      * Force default_transaction_isolation to READ COMMITTED.  We don't want
     608             :      * to pay the overhead of serializable mode, nor add any risk of causing
     609             :      * deadlocks or delaying other transactions.
     610             :      */
     611         598 :     SetConfigOption("default_transaction_isolation", "read committed",
     612             :                     PGC_SUSET, PGC_S_OVERRIDE);
     613             : 
     614             :     /*
     615             :      * Even when system is configured to use a different fetch consistency,
     616             :      * for autovac we always want fresh stats.
     617             :      */
     618         598 :     SetConfigOption("stats_fetch_consistency", "none", PGC_SUSET, PGC_S_OVERRIDE);
     619             : 
     620             :     /*
     621             :      * In emergency mode, just start a worker (unless shutdown was requested)
     622             :      * and go away.
     623             :      */
     624         598 :     if (!AutoVacuumingActive())
     625             :     {
     626           0 :         if (!ShutdownRequestPending)
     627           0 :             do_start_worker();
     628           0 :         proc_exit(0);           /* done */
     629             :     }
     630             : 
     631         598 :     AutoVacuumShmem->av_launcherpid = MyProcPid;
     632             : 
     633             :     /*
     634             :      * Create the initial database list.  The invariant we want this list to
     635             :      * keep is that it's ordered by decreasing next_time.  As soon as an entry
     636             :      * is updated to a higher time, it will be moved to the front (which is
     637             :      * correct because the only operation is to add autovacuum_naptime to the
     638             :      * entry, and time always increases).
     639             :      */
     640         598 :     rebuild_database_list(InvalidOid);
     641             : 
     642             :     /* loop until shutdown request */
     643        3134 :     while (!ShutdownRequestPending)
     644             :     {
     645             :         struct timeval nap;
     646        3134 :         TimestampTz current_time = 0;
     647             :         bool        can_launch;
     648             : 
     649             :         /*
     650             :          * This loop is a bit different from the normal use of WaitLatch,
     651             :          * because we'd like to sleep before the first launch of a child
     652             :          * process.  So it's WaitLatch, then ResetLatch, then check for
     653             :          * wakening conditions.
     654             :          */
     655             : 
     656        3134 :         launcher_determine_sleep(!dlist_is_empty(&AutoVacuumShmem->av_freeWorkers),
     657        3134 :                                  false, &nap);
     658             : 
     659             :         /*
     660             :          * Wait until naptime expires or we get some type of signal (all the
     661             :          * signal handlers will wake us by calling SetLatch).
     662             :          */
     663        3134 :         (void) WaitLatch(MyLatch,
     664             :                          WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
     665        3134 :                          (nap.tv_sec * 1000L) + (nap.tv_usec / 1000L),
     666             :                          WAIT_EVENT_AUTOVACUUM_MAIN);
     667             : 
     668        3128 :         ResetLatch(MyLatch);
     669             : 
     670        3128 :         HandleAutoVacLauncherInterrupts();
     671             : 
     672             :         /*
     673             :          * a worker finished, or postmaster signaled failure to start a worker
     674             :          */
     675        2536 :         if (got_SIGUSR2)
     676             :         {
     677          36 :             got_SIGUSR2 = false;
     678             : 
     679             :             /* rebalance cost limits, if needed */
     680          36 :             if (AutoVacuumShmem->av_signal[AutoVacRebalance])
     681             :             {
     682          18 :                 LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
     683          18 :                 AutoVacuumShmem->av_signal[AutoVacRebalance] = false;
     684          18 :                 autovac_recalculate_workers_for_balance();
     685          18 :                 LWLockRelease(AutovacuumLock);
     686             :             }
     687             : 
     688          36 :             if (AutoVacuumShmem->av_signal[AutoVacForkFailed])
     689             :             {
     690             :                 /*
     691             :                  * If the postmaster failed to start a new worker, we sleep
     692             :                  * for a little while and resend the signal.  The new worker's
     693             :                  * state is still in memory, so this is sufficient.  After
     694             :                  * that, we restart the main loop.
     695             :                  *
     696             :                  * XXX should we put a limit to the number of times we retry?
     697             :                  * I don't think it makes much sense, because a future start
     698             :                  * of a worker will continue to fail in the same way.
     699             :                  */
     700           0 :                 AutoVacuumShmem->av_signal[AutoVacForkFailed] = false;
     701           0 :                 pg_usleep(1000000L);    /* 1s */
     702           0 :                 SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER);
     703           0 :                 continue;
     704             :             }
     705             :         }
     706             : 
     707             :         /*
     708             :          * There are some conditions that we need to check before trying to
     709             :          * start a worker.  First, we need to make sure that there is a worker
     710             :          * slot available.  Second, we need to make sure that no other worker
     711             :          * failed while starting up.
     712             :          */
     713             : 
     714        2536 :         current_time = GetCurrentTimestamp();
     715        2536 :         LWLockAcquire(AutovacuumLock, LW_SHARED);
     716             : 
     717        2536 :         can_launch = !dlist_is_empty(&AutoVacuumShmem->av_freeWorkers);
     718             : 
     719        2536 :         if (AutoVacuumShmem->av_startingWorker != NULL)
     720             :         {
     721             :             int         waittime;
     722           0 :             WorkerInfo  worker = AutoVacuumShmem->av_startingWorker;
     723             : 
     724             :             /*
     725             :              * We can't launch another worker when another one is still
     726             :              * starting up (or failed while doing so), so just sleep for a bit
     727             :              * more; that worker will wake us up again as soon as it's ready.
     728             :              * We will only wait autovacuum_naptime seconds (up to a maximum
     729             :              * of 60 seconds) for this to happen however.  Note that failure
     730             :              * to connect to a particular database is not a problem here,
     731             :              * because the worker removes itself from the startingWorker
     732             :              * pointer before trying to connect.  Problems detected by the
     733             :              * postmaster (like fork() failure) are also reported and handled
     734             :              * differently.  The only problems that may cause this code to
     735             :              * fire are errors in the earlier sections of AutoVacWorkerMain,
     736             :              * before the worker removes the WorkerInfo from the
     737             :              * startingWorker pointer.
     738             :              */
     739           0 :             waittime = Min(autovacuum_naptime, 60) * 1000;
     740           0 :             if (TimestampDifferenceExceeds(worker->wi_launchtime, current_time,
     741             :                                            waittime))
     742             :             {
     743           0 :                 LWLockRelease(AutovacuumLock);
     744           0 :                 LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
     745             : 
     746             :                 /*
     747             :                  * No other process can put a worker in starting mode, so if
     748             :                  * startingWorker is still INVALID after exchanging our lock,
     749             :                  * we assume it's the same one we saw above (so we don't
     750             :                  * recheck the launch time).
     751             :                  */
     752           0 :                 if (AutoVacuumShmem->av_startingWorker != NULL)
     753             :                 {
     754           0 :                     worker = AutoVacuumShmem->av_startingWorker;
     755           0 :                     worker->wi_dboid = InvalidOid;
     756           0 :                     worker->wi_tableoid = InvalidOid;
     757           0 :                     worker->wi_sharedrel = false;
     758           0 :                     worker->wi_proc = NULL;
     759           0 :                     worker->wi_launchtime = 0;
     760           0 :                     dlist_push_head(&AutoVacuumShmem->av_freeWorkers,
     761             :                                     &worker->wi_links);
     762           0 :                     AutoVacuumShmem->av_startingWorker = NULL;
     763           0 :                     ereport(WARNING,
     764             :                             errmsg("autovacuum worker took too long to start; canceled"));
     765             :                 }
     766             :             }
     767             :             else
     768           0 :                 can_launch = false;
     769             :         }
     770        2536 :         LWLockRelease(AutovacuumLock);  /* either shared or exclusive */
     771             : 
     772             :         /* if we can't do anything, just go back to sleep */
     773        2536 :         if (!can_launch)
     774           0 :             continue;
     775             : 
     776             :         /* We're OK to start a new worker */
     777             : 
     778        2536 :         if (dlist_is_empty(&DatabaseList))
     779             :         {
     780             :             /*
     781             :              * Special case when the list is empty: start a worker right away.
     782             :              * This covers the initial case, when no database is in pgstats
     783             :              * (thus the list is empty).  Note that the constraints in
     784             :              * launcher_determine_sleep keep us from starting workers too
     785             :              * quickly (at most once every autovacuum_naptime when the list is
     786             :              * empty).
     787             :              */
     788          58 :             launch_worker(current_time);
     789             :         }
     790             :         else
     791             :         {
     792             :             /*
     793             :              * because rebuild_database_list constructs a list with most
     794             :              * distant adl_next_worker first, we obtain our database from the
     795             :              * tail of the list.
     796             :              */
     797             :             avl_dbase  *avdb;
     798             : 
     799        2478 :             avdb = dlist_tail_element(avl_dbase, adl_node, &DatabaseList);
     800             : 
     801             :             /*
     802             :              * launch a worker if next_worker is right now or it is in the
     803             :              * past
     804             :              */
     805        2478 :             if (TimestampDifferenceExceeds(avdb->adl_next_worker,
     806             :                                            current_time, 0))
     807          18 :                 launch_worker(current_time);
     808             :         }
     809             :     }
     810             : 
     811           0 :     AutoVacLauncherShutdown();
     812             : }
     813             : 
     814             : /*
     815             :  * Process any new interrupts.
     816             :  */
     817             : static void
     818        3128 : HandleAutoVacLauncherInterrupts(void)
     819             : {
     820             :     /* the normal shutdown case */
     821        3128 :     if (ShutdownRequestPending)
     822         592 :         AutoVacLauncherShutdown();
     823             : 
     824        2536 :     if (ConfigReloadPending)
     825             :     {
     826          50 :         ConfigReloadPending = false;
     827          50 :         ProcessConfigFile(PGC_SIGHUP);
     828             : 
     829             :         /* shutdown requested in config file? */
     830          50 :         if (!AutoVacuumingActive())
     831           0 :             AutoVacLauncherShutdown();
     832             : 
     833             :         /* rebuild the list in case the naptime changed */
     834          50 :         rebuild_database_list(InvalidOid);
     835             :     }
     836             : 
     837             :     /* Process barrier events */
     838        2536 :     if (ProcSignalBarrierPending)
     839          40 :         ProcessProcSignalBarrier();
     840             : 
     841             :     /* Perform logging of memory contexts of this process */
     842        2536 :     if (LogMemoryContextPending)
     843           0 :         ProcessLogMemoryContextInterrupt();
     844             : 
     845             :     /* Process sinval catchup interrupts that happened while sleeping */
     846        2536 :     ProcessCatchupInterrupt();
     847        2536 : }
     848             : 
     849             : /*
     850             :  * Perform a normal exit from the autovac launcher.
     851             :  */
     852             : static void
     853         592 : AutoVacLauncherShutdown(void)
     854             : {
     855         592 :     ereport(DEBUG1,
     856             :             (errmsg_internal("autovacuum launcher shutting down")));
     857         592 :     AutoVacuumShmem->av_launcherpid = 0;
     858             : 
     859         592 :     proc_exit(0);               /* done */
     860             : }
     861             : 
     862             : /*
     863             :  * Determine the time to sleep, based on the database list.
     864             :  *
     865             :  * The "canlaunch" parameter indicates whether we can start a worker right now,
     866             :  * for example due to the workers being all busy.  If this is false, we will
     867             :  * cause a long sleep, which will be interrupted when a worker exits.
     868             :  */
     869             : static void
     870        3134 : launcher_determine_sleep(bool canlaunch, bool recursing, struct timeval *nap)
     871             : {
     872             :     /*
     873             :      * We sleep until the next scheduled vacuum.  We trust that when the
     874             :      * database list was built, care was taken so that no entries have times
     875             :      * in the past; if the first entry has too close a next_worker value, or a
     876             :      * time in the past, we will sleep a small nominal time.
     877             :      */
     878        3134 :     if (!canlaunch)
     879             :     {
     880           0 :         nap->tv_sec = autovacuum_naptime;
     881           0 :         nap->tv_usec = 0;
     882             :     }
     883        3134 :     else if (!dlist_is_empty(&DatabaseList))
     884             :     {
     885        3018 :         TimestampTz current_time = GetCurrentTimestamp();
     886             :         TimestampTz next_wakeup;
     887             :         avl_dbase  *avdb;
     888             :         long        secs;
     889             :         int         usecs;
     890             : 
     891        3018 :         avdb = dlist_tail_element(avl_dbase, adl_node, &DatabaseList);
     892             : 
     893        3018 :         next_wakeup = avdb->adl_next_worker;
     894        3018 :         TimestampDifference(current_time, next_wakeup, &secs, &usecs);
     895             : 
     896        3018 :         nap->tv_sec = secs;
     897        3018 :         nap->tv_usec = usecs;
     898             :     }
     899             :     else
     900             :     {
     901             :         /* list is empty, sleep for whole autovacuum_naptime seconds  */
     902         116 :         nap->tv_sec = autovacuum_naptime;
     903         116 :         nap->tv_usec = 0;
     904             :     }
     905             : 
     906             :     /*
     907             :      * If the result is exactly zero, it means a database had an entry with
     908             :      * time in the past.  Rebuild the list so that the databases are evenly
     909             :      * distributed again, and recalculate the time to sleep.  This can happen
     910             :      * if there are more tables needing vacuum than workers, and they all take
     911             :      * longer to vacuum than autovacuum_naptime.
     912             :      *
     913             :      * We only recurse once.  rebuild_database_list should always return times
     914             :      * in the future, but it seems best not to trust too much on that.
     915             :      */
     916        3134 :     if (nap->tv_sec == 0 && nap->tv_usec == 0 && !recursing)
     917             :     {
     918           0 :         rebuild_database_list(InvalidOid);
     919           0 :         launcher_determine_sleep(canlaunch, true, nap);
     920           0 :         return;
     921             :     }
     922             : 
     923             :     /* The smallest time we'll allow the launcher to sleep. */
     924        3134 :     if (nap->tv_sec <= 0 && nap->tv_usec <= MIN_AUTOVAC_SLEEPTIME * 1000)
     925             :     {
     926           6 :         nap->tv_sec = 0;
     927           6 :         nap->tv_usec = MIN_AUTOVAC_SLEEPTIME * 1000;
     928             :     }
     929             : 
     930             :     /*
     931             :      * If the sleep time is too large, clamp it to an arbitrary maximum (plus
     932             :      * any fractional seconds, for simplicity).  This avoids an essentially
     933             :      * infinite sleep in strange cases like the system clock going backwards a
     934             :      * few years.
     935             :      */
     936        3134 :     if (nap->tv_sec > MAX_AUTOVAC_SLEEPTIME)
     937          22 :         nap->tv_sec = MAX_AUTOVAC_SLEEPTIME;
     938             : }
     939             : 
     940             : /*
     941             :  * Build an updated DatabaseList.  It must only contain databases that appear
     942             :  * in pgstats, and must be sorted by next_worker from highest to lowest,
     943             :  * distributed regularly across the next autovacuum_naptime interval.
     944             :  *
     945             :  * Receives the Oid of the database that made this list be generated (we call
     946             :  * this the "new" database, because when the database was already present on
     947             :  * the list, we expect that this function is not called at all).  The
     948             :  * preexisting list, if any, will be used to preserve the order of the
     949             :  * databases in the autovacuum_naptime period.  The new database is put at the
     950             :  * end of the interval.  The actual values are not saved, which should not be
     951             :  * much of a problem.
     952             :  */
     953             : static void
     954         656 : rebuild_database_list(Oid newdb)
     955             : {
     956             :     List       *dblist;
     957             :     ListCell   *cell;
     958             :     MemoryContext newcxt;
     959             :     MemoryContext oldcxt;
     960             :     MemoryContext tmpcxt;
     961             :     HASHCTL     hctl;
     962             :     int         score;
     963             :     int         nelems;
     964             :     HTAB       *dbhash;
     965             :     dlist_iter  iter;
     966             : 
     967         656 :     newcxt = AllocSetContextCreate(AutovacMemCxt,
     968             :                                    "Autovacuum database list",
     969             :                                    ALLOCSET_DEFAULT_SIZES);
     970         656 :     tmpcxt = AllocSetContextCreate(newcxt,
     971             :                                    "Autovacuum database list (tmp)",
     972             :                                    ALLOCSET_DEFAULT_SIZES);
     973         656 :     oldcxt = MemoryContextSwitchTo(tmpcxt);
     974             : 
     975             :     /*
     976             :      * Implementing this is not as simple as it sounds, because we need to put
     977             :      * the new database at the end of the list; next the databases that were
     978             :      * already on the list, and finally (at the tail of the list) all the
     979             :      * other databases that are not on the existing list.
     980             :      *
     981             :      * To do this, we build an empty hash table of scored databases.  We will
     982             :      * start with the lowest score (zero) for the new database, then
     983             :      * increasing scores for the databases in the existing list, in order, and
     984             :      * lastly increasing scores for all databases gotten via
     985             :      * get_database_list() that are not already on the hash.
     986             :      *
     987             :      * Then we will put all the hash elements into an array, sort the array by
     988             :      * score, and finally put the array elements into the new doubly linked
     989             :      * list.
     990             :      */
     991         656 :     hctl.keysize = sizeof(Oid);
     992         656 :     hctl.entrysize = sizeof(avl_dbase);
     993         656 :     hctl.hcxt = tmpcxt;
     994         656 :     dbhash = hash_create("autovacuum db hash", 20, &hctl, /* magic number here
     995             :                                                              * FIXME */
     996             :                          HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
     997             : 
     998             :     /* start by inserting the new database */
     999         656 :     score = 0;
    1000         656 :     if (OidIsValid(newdb))
    1001             :     {
    1002             :         avl_dbase  *db;
    1003             :         PgStat_StatDBEntry *entry;
    1004             : 
    1005             :         /* only consider this database if it has a pgstat entry */
    1006           8 :         entry = pgstat_fetch_stat_dbentry(newdb);
    1007           8 :         if (entry != NULL)
    1008             :         {
    1009             :             /* we assume it isn't found because the hash was just created */
    1010           8 :             db = hash_search(dbhash, &newdb, HASH_ENTER, NULL);
    1011             : 
    1012             :             /* hash_search already filled in the key */
    1013           8 :             db->adl_score = score++;
    1014             :             /* next_worker is filled in later */
    1015             :         }
    1016             :     }
    1017             : 
    1018             :     /* Now insert the databases from the existing list */
    1019         740 :     dlist_foreach(iter, &DatabaseList)
    1020             :     {
    1021          84 :         avl_dbase  *avdb = dlist_container(avl_dbase, adl_node, iter.cur);
    1022             :         avl_dbase  *db;
    1023             :         bool        found;
    1024             :         PgStat_StatDBEntry *entry;
    1025             : 
    1026             :         /*
    1027             :          * skip databases with no stat entries -- in particular, this gets rid
    1028             :          * of dropped databases
    1029             :          */
    1030          84 :         entry = pgstat_fetch_stat_dbentry(avdb->adl_datid);
    1031          84 :         if (entry == NULL)
    1032           0 :             continue;
    1033             : 
    1034          84 :         db = hash_search(dbhash, &(avdb->adl_datid), HASH_ENTER, &found);
    1035             : 
    1036          84 :         if (!found)
    1037             :         {
    1038             :             /* hash_search already filled in the key */
    1039          84 :             db->adl_score = score++;
    1040             :             /* next_worker is filled in later */
    1041             :         }
    1042             :     }
    1043             : 
    1044             :     /* finally, insert all qualifying databases not previously inserted */
    1045         656 :     dblist = get_database_list();
    1046        2910 :     foreach(cell, dblist)
    1047             :     {
    1048        2254 :         avw_dbase  *avdb = lfirst(cell);
    1049             :         avl_dbase  *db;
    1050             :         bool        found;
    1051             :         PgStat_StatDBEntry *entry;
    1052             : 
    1053             :         /* only consider databases with a pgstat entry */
    1054        2254 :         entry = pgstat_fetch_stat_dbentry(avdb->adw_datid);
    1055        2254 :         if (entry == NULL)
    1056        1410 :             continue;
    1057             : 
    1058         844 :         db = hash_search(dbhash, &(avdb->adw_datid), HASH_ENTER, &found);
    1059             :         /* only update the score if the database was not already on the hash */
    1060         844 :         if (!found)
    1061             :         {
    1062             :             /* hash_search already filled in the key */
    1063         752 :             db->adl_score = score++;
    1064             :             /* next_worker is filled in later */
    1065             :         }
    1066             :     }
    1067         656 :     nelems = score;
    1068             : 
    1069             :     /* from here on, the allocated memory belongs to the new list */
    1070         656 :     MemoryContextSwitchTo(newcxt);
    1071         656 :     dlist_init(&DatabaseList);
    1072             : 
    1073         656 :     if (nelems > 0)
    1074             :     {
    1075             :         TimestampTz current_time;
    1076             :         int         millis_increment;
    1077             :         avl_dbase  *dbary;
    1078             :         avl_dbase  *db;
    1079             :         HASH_SEQ_STATUS seq;
    1080             :         int         i;
    1081             : 
    1082             :         /* put all the hash elements into an array */
    1083         598 :         dbary = palloc(nelems * sizeof(avl_dbase));
    1084             : 
    1085         598 :         i = 0;
    1086         598 :         hash_seq_init(&seq, dbhash);
    1087        1442 :         while ((db = hash_seq_search(&seq)) != NULL)
    1088         844 :             memcpy(&(dbary[i++]), db, sizeof(avl_dbase));
    1089             : 
    1090             :         /* sort the array */
    1091         598 :         qsort(dbary, nelems, sizeof(avl_dbase), db_comparator);
    1092             : 
    1093             :         /*
    1094             :          * Determine the time interval between databases in the schedule. If
    1095             :          * we see that the configured naptime would take us to sleep times
    1096             :          * lower than our min sleep time (which launcher_determine_sleep is
    1097             :          * coded not to allow), silently use a larger naptime (but don't touch
    1098             :          * the GUC variable).
    1099             :          */
    1100         598 :         millis_increment = 1000.0 * autovacuum_naptime / nelems;
    1101         598 :         if (millis_increment <= MIN_AUTOVAC_SLEEPTIME)
    1102           0 :             millis_increment = MIN_AUTOVAC_SLEEPTIME * 1.1;
    1103             : 
    1104         598 :         current_time = GetCurrentTimestamp();
    1105             : 
    1106             :         /*
    1107             :          * move the elements from the array into the dlist, setting the
    1108             :          * next_worker while walking the array
    1109             :          */
    1110        1442 :         for (i = 0; i < nelems; i++)
    1111             :         {
    1112         844 :             db = &(dbary[i]);
    1113             : 
    1114         844 :             current_time = TimestampTzPlusMilliseconds(current_time,
    1115             :                                                        millis_increment);
    1116         844 :             db->adl_next_worker = current_time;
    1117             : 
    1118             :             /* later elements should go closer to the head of the list */
    1119         844 :             dlist_push_head(&DatabaseList, &db->adl_node);
    1120             :         }
    1121             :     }
    1122             : 
    1123             :     /* all done, clean up memory */
    1124         656 :     if (DatabaseListCxt != NULL)
    1125          58 :         MemoryContextDelete(DatabaseListCxt);
    1126         656 :     MemoryContextDelete(tmpcxt);
    1127         656 :     DatabaseListCxt = newcxt;
    1128         656 :     MemoryContextSwitchTo(oldcxt);
    1129         656 : }
    1130             : 
    1131             : /* qsort comparator for avl_dbase, using adl_score */
    1132             : static int
    1133         332 : db_comparator(const void *a, const void *b)
    1134             : {
    1135         332 :     if (((const avl_dbase *) a)->adl_score == ((const avl_dbase *) b)->adl_score)
    1136           0 :         return 0;
    1137             :     else
    1138         332 :         return (((const avl_dbase *) a)->adl_score < ((const avl_dbase *) b)->adl_score) ? 1 : -1;
    1139             : }
    1140             : 
    1141             : /*
    1142             :  * do_start_worker
    1143             :  *
    1144             :  * Bare-bones procedure for starting an autovacuum worker from the launcher.
    1145             :  * It determines what database to work on, sets up shared memory stuff and
    1146             :  * signals postmaster to start the worker.  It fails gracefully if invoked when
    1147             :  * autovacuum_workers are already active.
    1148             :  *
    1149             :  * Return value is the OID of the database that the worker is going to process,
    1150             :  * or InvalidOid if no worker was actually started.
    1151             :  */
    1152             : static Oid
    1153          76 : do_start_worker(void)
    1154             : {
    1155             :     List       *dblist;
    1156             :     ListCell   *cell;
    1157             :     TransactionId xidForceLimit;
    1158             :     MultiXactId multiForceLimit;
    1159             :     bool        for_xid_wrap;
    1160             :     bool        for_multi_wrap;
    1161             :     avw_dbase  *avdb;
    1162             :     TimestampTz current_time;
    1163          76 :     bool        skipit = false;
    1164          76 :     Oid         retval = InvalidOid;
    1165             :     MemoryContext tmpcxt,
    1166             :                 oldcxt;
    1167             : 
    1168             :     /* return quickly when there are no free workers */
    1169          76 :     LWLockAcquire(AutovacuumLock, LW_SHARED);
    1170          76 :     if (dlist_is_empty(&AutoVacuumShmem->av_freeWorkers))
    1171             :     {
    1172           0 :         LWLockRelease(AutovacuumLock);
    1173           0 :         return InvalidOid;
    1174             :     }
    1175          76 :     LWLockRelease(AutovacuumLock);
    1176             : 
    1177             :     /*
    1178             :      * Create and switch to a temporary context to avoid leaking the memory
    1179             :      * allocated for the database list.
    1180             :      */
    1181          76 :     tmpcxt = AllocSetContextCreate(CurrentMemoryContext,
    1182             :                                    "Autovacuum start worker (tmp)",
    1183             :                                    ALLOCSET_DEFAULT_SIZES);
    1184          76 :     oldcxt = MemoryContextSwitchTo(tmpcxt);
    1185             : 
    1186             :     /* Get a list of databases */
    1187          76 :     dblist = get_database_list();
    1188             : 
    1189             :     /*
    1190             :      * Determine the oldest datfrozenxid/relfrozenxid that we will allow to
    1191             :      * pass without forcing a vacuum.  (This limit can be tightened for
    1192             :      * particular tables, but not loosened.)
    1193             :      */
    1194          76 :     recentXid = ReadNextTransactionId();
    1195          76 :     xidForceLimit = recentXid - autovacuum_freeze_max_age;
    1196             :     /* ensure it's a "normal" XID, else TransactionIdPrecedes misbehaves */
    1197             :     /* this can cause the limit to go backwards by 3, but that's OK */
    1198          76 :     if (xidForceLimit < FirstNormalTransactionId)
    1199           0 :         xidForceLimit -= FirstNormalTransactionId;
    1200             : 
    1201             :     /* Also determine the oldest datminmxid we will consider. */
    1202          76 :     recentMulti = ReadNextMultiXactId();
    1203          76 :     multiForceLimit = recentMulti - MultiXactMemberFreezeThreshold();
    1204          76 :     if (multiForceLimit < FirstMultiXactId)
    1205           0 :         multiForceLimit -= FirstMultiXactId;
    1206             : 
    1207             :     /*
    1208             :      * Choose a database to connect to.  We pick the database that was least
    1209             :      * recently auto-vacuumed, or one that needs vacuuming to prevent Xid
    1210             :      * wraparound-related data loss.  If any db at risk of Xid wraparound is
    1211             :      * found, we pick the one with oldest datfrozenxid, independently of
    1212             :      * autovacuum times; similarly we pick the one with the oldest datminmxid
    1213             :      * if any is in MultiXactId wraparound.  Note that those in Xid wraparound
    1214             :      * danger are given more priority than those in multi wraparound danger.
    1215             :      *
    1216             :      * Note that a database with no stats entry is not considered, except for
    1217             :      * Xid wraparound purposes.  The theory is that if no one has ever
    1218             :      * connected to it since the stats were last initialized, it doesn't need
    1219             :      * vacuuming.
    1220             :      *
    1221             :      * XXX This could be improved if we had more info about whether it needs
    1222             :      * vacuuming before connecting to it.  Perhaps look through the pgstats
    1223             :      * data for the database's tables?  One idea is to keep track of the
    1224             :      * number of new and dead tuples per database in pgstats.  However it
    1225             :      * isn't clear how to construct a metric that measures that and not cause
    1226             :      * starvation for less busy databases.
    1227             :      */
    1228          76 :     avdb = NULL;
    1229          76 :     for_xid_wrap = false;
    1230          76 :     for_multi_wrap = false;
    1231          76 :     current_time = GetCurrentTimestamp();
    1232         350 :     foreach(cell, dblist)
    1233             :     {
    1234         274 :         avw_dbase  *tmp = lfirst(cell);
    1235             :         dlist_iter  iter;
    1236             : 
    1237             :         /* Check to see if this one is at risk of wraparound */
    1238         274 :         if (TransactionIdPrecedes(tmp->adw_frozenxid, xidForceLimit))
    1239             :         {
    1240           0 :             if (avdb == NULL ||
    1241           0 :                 TransactionIdPrecedes(tmp->adw_frozenxid,
    1242             :                                       avdb->adw_frozenxid))
    1243           0 :                 avdb = tmp;
    1244           0 :             for_xid_wrap = true;
    1245         242 :             continue;
    1246             :         }
    1247         274 :         else if (for_xid_wrap)
    1248           0 :             continue;           /* ignore not-at-risk DBs */
    1249         274 :         else if (MultiXactIdPrecedes(tmp->adw_minmulti, multiForceLimit))
    1250             :         {
    1251           0 :             if (avdb == NULL ||
    1252           0 :                 MultiXactIdPrecedes(tmp->adw_minmulti, avdb->adw_minmulti))
    1253           0 :                 avdb = tmp;
    1254           0 :             for_multi_wrap = true;
    1255           0 :             continue;
    1256             :         }
    1257         274 :         else if (for_multi_wrap)
    1258           0 :             continue;           /* ignore not-at-risk DBs */
    1259             : 
    1260             :         /* Find pgstat entry if any */
    1261         274 :         tmp->adw_entry = pgstat_fetch_stat_dbentry(tmp->adw_datid);
    1262             : 
    1263             :         /*
    1264             :          * Skip a database with no pgstat entry; it means it hasn't seen any
    1265             :          * activity.
    1266             :          */
    1267         274 :         if (!tmp->adw_entry)
    1268         222 :             continue;
    1269             : 
    1270             :         /*
    1271             :          * Also, skip a database that appears on the database list as having
    1272             :          * been processed recently (less than autovacuum_naptime seconds ago).
    1273             :          * We do this so that we don't select a database which we just
    1274             :          * selected, but that pgstat hasn't gotten around to updating the last
    1275             :          * autovacuum time yet.
    1276             :          */
    1277          52 :         skipit = false;
    1278             : 
    1279          96 :         dlist_reverse_foreach(iter, &DatabaseList)
    1280             :         {
    1281          82 :             avl_dbase  *dbp = dlist_container(avl_dbase, adl_node, iter.cur);
    1282             : 
    1283          82 :             if (dbp->adl_datid == tmp->adw_datid)
    1284             :             {
    1285             :                 /*
    1286             :                  * Skip this database if its next_worker value falls between
    1287             :                  * the current time and the current time plus naptime.
    1288             :                  */
    1289          38 :                 if (!TimestampDifferenceExceeds(dbp->adl_next_worker,
    1290          20 :                                                 current_time, 0) &&
    1291          20 :                     !TimestampDifferenceExceeds(current_time,
    1292             :                                                 dbp->adl_next_worker,
    1293             :                                                 autovacuum_naptime * 1000))
    1294          20 :                     skipit = true;
    1295             : 
    1296          38 :                 break;
    1297             :             }
    1298             :         }
    1299          52 :         if (skipit)
    1300          20 :             continue;
    1301             : 
    1302             :         /*
    1303             :          * Remember the db with oldest autovac time.  (If we are here, both
    1304             :          * tmp->entry and db->entry must be non-null.)
    1305             :          */
    1306          32 :         if (avdb == NULL ||
    1307          14 :             tmp->adw_entry->last_autovac_time < avdb->adw_entry->last_autovac_time)
    1308          18 :             avdb = tmp;
    1309             :     }
    1310             : 
    1311             :     /* Found a database -- process it */
    1312          76 :     if (avdb != NULL)
    1313             :     {
    1314             :         WorkerInfo  worker;
    1315             :         dlist_node *wptr;
    1316             : 
    1317          18 :         LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    1318             : 
    1319             :         /*
    1320             :          * Get a worker entry from the freelist.  We checked above, so there
    1321             :          * really should be a free slot.
    1322             :          */
    1323          18 :         wptr = dlist_pop_head_node(&AutoVacuumShmem->av_freeWorkers);
    1324             : 
    1325          18 :         worker = dlist_container(WorkerInfoData, wi_links, wptr);
    1326          18 :         worker->wi_dboid = avdb->adw_datid;
    1327          18 :         worker->wi_proc = NULL;
    1328          18 :         worker->wi_launchtime = GetCurrentTimestamp();
    1329             : 
    1330          18 :         AutoVacuumShmem->av_startingWorker = worker;
    1331             : 
    1332          18 :         LWLockRelease(AutovacuumLock);
    1333             : 
    1334          18 :         SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER);
    1335             : 
    1336          18 :         retval = avdb->adw_datid;
    1337             :     }
    1338          58 :     else if (skipit)
    1339             :     {
    1340             :         /*
    1341             :          * If we skipped all databases on the list, rebuild it, because it
    1342             :          * probably contains a dropped database.
    1343             :          */
    1344           0 :         rebuild_database_list(InvalidOid);
    1345             :     }
    1346             : 
    1347          76 :     MemoryContextSwitchTo(oldcxt);
    1348          76 :     MemoryContextDelete(tmpcxt);
    1349             : 
    1350          76 :     return retval;
    1351             : }
    1352             : 
    1353             : /*
    1354             :  * launch_worker
    1355             :  *
    1356             :  * Wrapper for starting a worker from the launcher.  Besides actually starting
    1357             :  * it, update the database list to reflect the next time that another one will
    1358             :  * need to be started on the selected database.  The actual database choice is
    1359             :  * left to do_start_worker.
    1360             :  *
    1361             :  * This routine is also expected to insert an entry into the database list if
    1362             :  * the selected database was previously absent from the list.
    1363             :  */
    1364             : static void
    1365          76 : launch_worker(TimestampTz now)
    1366             : {
    1367             :     Oid         dbid;
    1368             :     dlist_iter  iter;
    1369             : 
    1370          76 :     dbid = do_start_worker();
    1371          76 :     if (OidIsValid(dbid))
    1372             :     {
    1373          18 :         bool        found = false;
    1374             : 
    1375             :         /*
    1376             :          * Walk the database list and update the corresponding entry.  If the
    1377             :          * database is not on the list, we'll recreate the list.
    1378             :          */
    1379          46 :         dlist_foreach(iter, &DatabaseList)
    1380             :         {
    1381          38 :             avl_dbase  *avdb = dlist_container(avl_dbase, adl_node, iter.cur);
    1382             : 
    1383          38 :             if (avdb->adl_datid == dbid)
    1384             :             {
    1385          10 :                 found = true;
    1386             : 
    1387             :                 /*
    1388             :                  * add autovacuum_naptime seconds to the current time, and use
    1389             :                  * that as the new "next_worker" field for this database.
    1390             :                  */
    1391          10 :                 avdb->adl_next_worker =
    1392          10 :                     TimestampTzPlusMilliseconds(now, autovacuum_naptime * 1000);
    1393             : 
    1394          10 :                 dlist_move_head(&DatabaseList, iter.cur);
    1395          10 :                 break;
    1396             :             }
    1397             :         }
    1398             : 
    1399             :         /*
    1400             :          * If the database was not present in the database list, we rebuild
    1401             :          * the list.  It's possible that the database does not get into the
    1402             :          * list anyway, for example if it's a database that doesn't have a
    1403             :          * pgstat entry, but this is not a problem because we don't want to
    1404             :          * schedule workers regularly into those in any case.
    1405             :          */
    1406          18 :         if (!found)
    1407           8 :             rebuild_database_list(dbid);
    1408             :     }
    1409          76 : }
    1410             : 
    1411             : /*
    1412             :  * Called from postmaster to signal a failure to fork a process to become
    1413             :  * worker.  The postmaster should kill(SIGUSR2) the launcher shortly
    1414             :  * after calling this function.
    1415             :  */
    1416             : void
    1417           0 : AutoVacWorkerFailed(void)
    1418             : {
    1419           0 :     AutoVacuumShmem->av_signal[AutoVacForkFailed] = true;
    1420           0 : }
    1421             : 
    1422             : /* SIGUSR2: a worker is up and running, or just finished, or failed to fork */
    1423             : static void
    1424          36 : avl_sigusr2_handler(SIGNAL_ARGS)
    1425             : {
    1426          36 :     int         save_errno = errno;
    1427             : 
    1428          36 :     got_SIGUSR2 = true;
    1429          36 :     SetLatch(MyLatch);
    1430             : 
    1431          36 :     errno = save_errno;
    1432          36 : }
    1433             : 
    1434             : 
    1435             : /********************************************************************
    1436             :  *                    AUTOVACUUM WORKER CODE
    1437             :  ********************************************************************/
    1438             : 
    1439             : #ifdef EXEC_BACKEND
    1440             : /*
    1441             :  * forkexec routines for the autovacuum worker.
    1442             :  *
    1443             :  * Format up the arglist, then fork and exec.
    1444             :  */
    1445             : static pid_t
    1446             : avworker_forkexec(void)
    1447             : {
    1448             :     char       *av[10];
    1449             :     int         ac = 0;
    1450             : 
    1451             :     av[ac++] = "postgres";
    1452             :     av[ac++] = "--forkavworker";
    1453             :     av[ac++] = NULL;            /* filled in by postmaster_forkexec */
    1454             :     av[ac] = NULL;
    1455             : 
    1456             :     Assert(ac < lengthof(av));
    1457             : 
    1458             :     return postmaster_forkexec(ac, av);
    1459             : }
    1460             : 
    1461             : /*
    1462             :  * We need this set from the outside, before InitProcess is called
    1463             :  */
    1464             : void
    1465             : AutovacuumWorkerIAm(void)
    1466             : {
    1467             :     am_autovacuum_worker = true;
    1468             : }
    1469             : #endif
    1470             : 
    1471             : /*
    1472             :  * Main entry point for autovacuum worker process.
    1473             :  *
    1474             :  * This code is heavily based on pgarch.c, q.v.
    1475             :  */
    1476             : int
    1477          18 : StartAutoVacWorker(void)
    1478             : {
    1479             :     pid_t       worker_pid;
    1480             : 
    1481             : #ifdef EXEC_BACKEND
    1482             :     switch ((worker_pid = avworker_forkexec()))
    1483             : #else
    1484          18 :     switch ((worker_pid = fork_process()))
    1485             : #endif
    1486             :     {
    1487           0 :         case -1:
    1488           0 :             ereport(LOG,
    1489             :                     (errmsg("could not fork autovacuum worker process: %m")));
    1490           0 :             return 0;
    1491             : 
    1492             : #ifndef EXEC_BACKEND
    1493          18 :         case 0:
    1494             :             /* in postmaster child ... */
    1495          18 :             InitPostmasterChild();
    1496             : 
    1497             :             /* Close the postmaster's sockets */
    1498          18 :             ClosePostmasterPorts(false);
    1499             : 
    1500          18 :             AutoVacWorkerMain(0, NULL);
    1501             :             break;
    1502             : #endif
    1503          18 :         default:
    1504          18 :             return (int) worker_pid;
    1505             :     }
    1506             : 
    1507             :     /* shouldn't get here */
    1508             :     return 0;
    1509             : }
    1510             : 
    1511             : /*
    1512             :  * AutoVacWorkerMain
    1513             :  */
    1514             : NON_EXEC_STATIC void
    1515          18 : AutoVacWorkerMain(int argc, char *argv[])
    1516             : {
    1517             :     sigjmp_buf  local_sigjmp_buf;
    1518             :     Oid         dbid;
    1519             : 
    1520          18 :     am_autovacuum_worker = true;
    1521             : 
    1522          18 :     MyBackendType = B_AUTOVAC_WORKER;
    1523          18 :     init_ps_display(NULL);
    1524             : 
    1525          18 :     SetProcessingMode(InitProcessing);
    1526             : 
    1527             :     /*
    1528             :      * Set up signal handlers.  We operate on databases much like a regular
    1529             :      * backend, so we use the same signal handling.  See equivalent code in
    1530             :      * tcop/postgres.c.
    1531             :      */
    1532          18 :     pqsignal(SIGHUP, SignalHandlerForConfigReload);
    1533             : 
    1534             :     /*
    1535             :      * SIGINT is used to signal canceling the current table's vacuum; SIGTERM
    1536             :      * means abort and exit cleanly, and SIGQUIT means abandon ship.
    1537             :      */
    1538          18 :     pqsignal(SIGINT, StatementCancelHandler);
    1539          18 :     pqsignal(SIGTERM, die);
    1540             :     /* SIGQUIT handler was already set up by InitPostmasterChild */
    1541             : 
    1542          18 :     InitializeTimeouts();       /* establishes SIGALRM handler */
    1543             : 
    1544          18 :     pqsignal(SIGPIPE, SIG_IGN);
    1545          18 :     pqsignal(SIGUSR1, procsignal_sigusr1_handler);
    1546          18 :     pqsignal(SIGUSR2, SIG_IGN);
    1547          18 :     pqsignal(SIGFPE, FloatExceptionHandler);
    1548          18 :     pqsignal(SIGCHLD, SIG_DFL);
    1549             : 
    1550             :     /*
    1551             :      * Create a per-backend PGPROC struct in shared memory, except in the
    1552             :      * EXEC_BACKEND case where this was done in SubPostmasterMain. We must do
    1553             :      * this before we can use LWLocks (and in the EXEC_BACKEND case we already
    1554             :      * had to do some stuff with LWLocks).
    1555             :      */
    1556             : #ifndef EXEC_BACKEND
    1557          18 :     InitProcess();
    1558             : #endif
    1559             : 
    1560             :     /* Early initialization */
    1561          18 :     BaseInit();
    1562             : 
    1563             :     /*
    1564             :      * If an exception is encountered, processing resumes here.
    1565             :      *
    1566             :      * Unlike most auxiliary processes, we don't attempt to continue
    1567             :      * processing after an error; we just clean up and exit.  The autovac
    1568             :      * launcher is responsible for spawning another worker later.
    1569             :      *
    1570             :      * Note that we use sigsetjmp(..., 1), so that the prevailing signal mask
    1571             :      * (to wit, BlockSig) will be restored when longjmp'ing to here.  Thus,
    1572             :      * signals other than SIGQUIT will be blocked until we exit.  It might
    1573             :      * seem that this policy makes the HOLD_INTERRUPTS() call redundant, but
    1574             :      * it is not since InterruptPending might be set already.
    1575             :      */
    1576          18 :     if (sigsetjmp(local_sigjmp_buf, 1) != 0)
    1577             :     {
    1578             :         /* since not using PG_TRY, must reset error stack by hand */
    1579           0 :         error_context_stack = NULL;
    1580             : 
    1581             :         /* Prevents interrupts while cleaning up */
    1582           0 :         HOLD_INTERRUPTS();
    1583             : 
    1584             :         /* Report the error to the server log */
    1585           0 :         EmitErrorReport();
    1586             : 
    1587             :         /*
    1588             :          * We can now go away.  Note that because we called InitProcess, a
    1589             :          * callback was registered to do ProcKill, which will clean up
    1590             :          * necessary state.
    1591             :          */
    1592           0 :         proc_exit(0);
    1593             :     }
    1594             : 
    1595             :     /* We can now handle ereport(ERROR) */
    1596          18 :     PG_exception_stack = &local_sigjmp_buf;
    1597             : 
    1598          18 :     sigprocmask(SIG_SETMASK, &UnBlockSig, NULL);
    1599             : 
    1600             :     /*
    1601             :      * Set always-secure search path, so malicious users can't redirect user
    1602             :      * code (e.g. pg_index.indexprs).  (That code runs in a
    1603             :      * SECURITY_RESTRICTED_OPERATION sandbox, so malicious users could not
    1604             :      * take control of the entire autovacuum worker in any case.)
    1605             :      */
    1606          18 :     SetConfigOption("search_path", "", PGC_SUSET, PGC_S_OVERRIDE);
    1607             : 
    1608             :     /*
    1609             :      * Force zero_damaged_pages OFF in the autovac process, even if it is set
    1610             :      * in postgresql.conf.  We don't really want such a dangerous option being
    1611             :      * applied non-interactively.
    1612             :      */
    1613          18 :     SetConfigOption("zero_damaged_pages", "false", PGC_SUSET, PGC_S_OVERRIDE);
    1614             : 
    1615             :     /*
    1616             :      * Force settable timeouts off to avoid letting these settings prevent
    1617             :      * regular maintenance from being executed.
    1618             :      */
    1619          18 :     SetConfigOption("statement_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
    1620          18 :     SetConfigOption("lock_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
    1621          18 :     SetConfigOption("idle_in_transaction_session_timeout", "0",
    1622             :                     PGC_SUSET, PGC_S_OVERRIDE);
    1623             : 
    1624             :     /*
    1625             :      * Force default_transaction_isolation to READ COMMITTED.  We don't want
    1626             :      * to pay the overhead of serializable mode, nor add any risk of causing
    1627             :      * deadlocks or delaying other transactions.
    1628             :      */
    1629          18 :     SetConfigOption("default_transaction_isolation", "read committed",
    1630             :                     PGC_SUSET, PGC_S_OVERRIDE);
    1631             : 
    1632             :     /*
    1633             :      * Force synchronous replication off to allow regular maintenance even if
    1634             :      * we are waiting for standbys to connect. This is important to ensure we
    1635             :      * aren't blocked from performing anti-wraparound tasks.
    1636             :      */
    1637          18 :     if (synchronous_commit > SYNCHRONOUS_COMMIT_LOCAL_FLUSH)
    1638          18 :         SetConfigOption("synchronous_commit", "local",
    1639             :                         PGC_SUSET, PGC_S_OVERRIDE);
    1640             : 
    1641             :     /*
    1642             :      * Even when system is configured to use a different fetch consistency,
    1643             :      * for autovac we always want fresh stats.
    1644             :      */
    1645          18 :     SetConfigOption("stats_fetch_consistency", "none", PGC_SUSET, PGC_S_OVERRIDE);
    1646             : 
    1647             :     /*
    1648             :      * Get the info about the database we're going to work on.
    1649             :      */
    1650          18 :     LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    1651             : 
    1652             :     /*
    1653             :      * beware of startingWorker being INVALID; this should normally not
    1654             :      * happen, but if a worker fails after forking and before this, the
    1655             :      * launcher might have decided to remove it from the queue and start
    1656             :      * again.
    1657             :      */
    1658          18 :     if (AutoVacuumShmem->av_startingWorker != NULL)
    1659             :     {
    1660          18 :         MyWorkerInfo = AutoVacuumShmem->av_startingWorker;
    1661          18 :         dbid = MyWorkerInfo->wi_dboid;
    1662          18 :         MyWorkerInfo->wi_proc = MyProc;
    1663             : 
    1664             :         /* insert into the running list */
    1665          18 :         dlist_push_head(&AutoVacuumShmem->av_runningWorkers,
    1666          18 :                         &MyWorkerInfo->wi_links);
    1667             : 
    1668             :         /*
    1669             :          * remove from the "starting" pointer, so that the launcher can start
    1670             :          * a new worker if required
    1671             :          */
    1672          18 :         AutoVacuumShmem->av_startingWorker = NULL;
    1673          18 :         LWLockRelease(AutovacuumLock);
    1674             : 
    1675          18 :         on_shmem_exit(FreeWorkerInfo, 0);
    1676             : 
    1677             :         /* wake up the launcher */
    1678          18 :         if (AutoVacuumShmem->av_launcherpid != 0)
    1679          18 :             kill(AutoVacuumShmem->av_launcherpid, SIGUSR2);
    1680             :     }
    1681             :     else
    1682             :     {
    1683             :         /* no worker entry for me, go away */
    1684           0 :         elog(WARNING, "autovacuum worker started without a worker entry");
    1685           0 :         dbid = InvalidOid;
    1686           0 :         LWLockRelease(AutovacuumLock);
    1687             :     }
    1688             : 
    1689          18 :     if (OidIsValid(dbid))
    1690             :     {
    1691             :         char        dbname[NAMEDATALEN];
    1692             : 
    1693             :         /*
    1694             :          * Report autovac startup to the cumulative stats system.  We
    1695             :          * deliberately do this before InitPostgres, so that the
    1696             :          * last_autovac_time will get updated even if the connection attempt
    1697             :          * fails.  This is to prevent autovac from getting "stuck" repeatedly
    1698             :          * selecting an unopenable database, rather than making any progress
    1699             :          * on stuff it can connect to.
    1700             :          */
    1701          18 :         pgstat_report_autovac(dbid);
    1702             : 
    1703             :         /*
    1704             :          * Connect to the selected database, specifying no particular user
    1705             :          *
    1706             :          * Note: if we have selected a just-deleted database (due to using
    1707             :          * stale stats info), we'll fail and exit here.
    1708             :          */
    1709          18 :         InitPostgres(NULL, dbid, NULL, InvalidOid, false, false,
    1710             :                      dbname);
    1711          18 :         SetProcessingMode(NormalProcessing);
    1712          18 :         set_ps_display(dbname);
    1713          18 :         ereport(DEBUG1,
    1714             :                 (errmsg_internal("autovacuum: processing database \"%s\"", dbname)));
    1715             : 
    1716          18 :         if (PostAuthDelay)
    1717           0 :             pg_usleep(PostAuthDelay * 1000000L);
    1718             : 
    1719             :         /* And do an appropriate amount of work */
    1720          18 :         recentXid = ReadNextTransactionId();
    1721          18 :         recentMulti = ReadNextMultiXactId();
    1722          18 :         do_autovacuum();
    1723             :     }
    1724             : 
    1725             :     /*
    1726             :      * The launcher will be notified of my death in ProcKill, *if* we managed
    1727             :      * to get a worker slot at all
    1728             :      */
    1729             : 
    1730             :     /* All done, go away */
    1731          18 :     proc_exit(0);
    1732             : }
    1733             : 
    1734             : /*
    1735             :  * Return a WorkerInfo to the free list
    1736             :  */
    1737             : static void
    1738          18 : FreeWorkerInfo(int code, Datum arg)
    1739             : {
    1740          18 :     if (MyWorkerInfo != NULL)
    1741             :     {
    1742          18 :         LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    1743             : 
    1744             :         /*
    1745             :          * Wake the launcher up so that he can launch a new worker immediately
    1746             :          * if required.  We only save the launcher's PID in local memory here;
    1747             :          * the actual signal will be sent when the PGPROC is recycled.  Note
    1748             :          * that we always do this, so that the launcher can rebalance the cost
    1749             :          * limit setting of the remaining workers.
    1750             :          *
    1751             :          * We somewhat ignore the risk that the launcher changes its PID
    1752             :          * between us reading it and the actual kill; we expect ProcKill to be
    1753             :          * called shortly after us, and we assume that PIDs are not reused too
    1754             :          * quickly after a process exits.
    1755             :          */
    1756          18 :         AutovacuumLauncherPid = AutoVacuumShmem->av_launcherpid;
    1757             : 
    1758          18 :         dlist_delete(&MyWorkerInfo->wi_links);
    1759          18 :         MyWorkerInfo->wi_dboid = InvalidOid;
    1760          18 :         MyWorkerInfo->wi_tableoid = InvalidOid;
    1761          18 :         MyWorkerInfo->wi_sharedrel = false;
    1762          18 :         MyWorkerInfo->wi_proc = NULL;
    1763          18 :         MyWorkerInfo->wi_launchtime = 0;
    1764          18 :         pg_atomic_clear_flag(&MyWorkerInfo->wi_dobalance);
    1765          18 :         dlist_push_head(&AutoVacuumShmem->av_freeWorkers,
    1766          18 :                         &MyWorkerInfo->wi_links);
    1767             :         /* not mine anymore */
    1768          18 :         MyWorkerInfo = NULL;
    1769             : 
    1770             :         /*
    1771             :          * now that we're inactive, cause a rebalancing of the surviving
    1772             :          * workers
    1773             :          */
    1774          18 :         AutoVacuumShmem->av_signal[AutoVacRebalance] = true;
    1775          18 :         LWLockRelease(AutovacuumLock);
    1776             :     }
    1777          18 : }
    1778             : 
    1779             : /*
    1780             :  * Update vacuum cost-based delay-related parameters for autovacuum workers and
    1781             :  * backends executing VACUUM or ANALYZE using the value of relevant GUCs and
    1782             :  * global state. This must be called during setup for vacuum and after every
    1783             :  * config reload to ensure up-to-date values.
    1784             :  */
    1785             : void
    1786       10666 : VacuumUpdateCosts(void)
    1787             : {
    1788       10666 :     if (MyWorkerInfo)
    1789             :     {
    1790         696 :         if (av_storage_param_cost_delay >= 0)
    1791           0 :             vacuum_cost_delay = av_storage_param_cost_delay;
    1792         696 :         else if (autovacuum_vac_cost_delay >= 0)
    1793         696 :             vacuum_cost_delay = autovacuum_vac_cost_delay;
    1794             :         else
    1795             :             /* fall back to VacuumCostDelay */
    1796           0 :             vacuum_cost_delay = VacuumCostDelay;
    1797             : 
    1798         696 :         AutoVacuumUpdateCostLimit();
    1799             :     }
    1800             :     else
    1801             :     {
    1802             :         /* Must be explicit VACUUM or ANALYZE */
    1803        9970 :         vacuum_cost_delay = VacuumCostDelay;
    1804        9970 :         vacuum_cost_limit = VacuumCostLimit;
    1805             :     }
    1806             : 
    1807             :     /*
    1808             :      * If configuration changes are allowed to impact VacuumCostActive, make
    1809             :      * sure it is updated.
    1810             :      */
    1811       10666 :     if (VacuumFailsafeActive)
    1812             :         Assert(!VacuumCostActive);
    1813       10666 :     else if (vacuum_cost_delay > 0)
    1814         696 :         VacuumCostActive = true;
    1815             :     else
    1816             :     {
    1817        9970 :         VacuumCostActive = false;
    1818        9970 :         VacuumCostBalance = 0;
    1819             :     }
    1820             : 
    1821             :     /*
    1822             :      * Since the cost logging requires a lock, avoid rendering the log message
    1823             :      * in case we are using a message level where the log wouldn't be emitted.
    1824             :      */
    1825       10666 :     if (MyWorkerInfo && message_level_is_interesting(DEBUG2))
    1826             :     {
    1827             :         Oid         dboid,
    1828             :                     tableoid;
    1829             : 
    1830             :         Assert(!LWLockHeldByMe(AutovacuumLock));
    1831             : 
    1832           0 :         LWLockAcquire(AutovacuumLock, LW_SHARED);
    1833           0 :         dboid = MyWorkerInfo->wi_dboid;
    1834           0 :         tableoid = MyWorkerInfo->wi_tableoid;
    1835           0 :         LWLockRelease(AutovacuumLock);
    1836             : 
    1837           0 :         elog(DEBUG2,
    1838             :              "Autovacuum VacuumUpdateCosts(db=%u, rel=%u, dobalance=%s, cost_limit=%d, cost_delay=%g active=%s failsafe=%s)",
    1839             :              dboid, tableoid, pg_atomic_unlocked_test_flag(&MyWorkerInfo->wi_dobalance) ? "no" : "yes",
    1840             :              vacuum_cost_limit, vacuum_cost_delay,
    1841             :              vacuum_cost_delay > 0 ? "yes" : "no",
    1842             :              VacuumFailsafeActive ? "yes" : "no");
    1843             :     }
    1844       10666 : }
    1845             : 
    1846             : /*
    1847             :  * Update vacuum_cost_limit with the correct value for an autovacuum worker,
    1848             :  * given the value of other relevant cost limit parameters and the number of
    1849             :  * workers across which the limit must be balanced. Autovacuum workers must
    1850             :  * call this regularly in case av_nworkersForBalance has been updated by
    1851             :  * another worker or by the autovacuum launcher. They must also call it after a
    1852             :  * config reload.
    1853             :  */
    1854             : void
    1855        1380 : AutoVacuumUpdateCostLimit(void)
    1856             : {
    1857        1380 :     if (!MyWorkerInfo)
    1858           0 :         return;
    1859             : 
    1860             :     /*
    1861             :      * note: in cost_limit, zero also means use value from elsewhere, because
    1862             :      * zero is not a valid value.
    1863             :      */
    1864             : 
    1865        1380 :     if (av_storage_param_cost_limit > 0)
    1866           0 :         vacuum_cost_limit = av_storage_param_cost_limit;
    1867             :     else
    1868             :     {
    1869             :         int         nworkers_for_balance;
    1870             : 
    1871        1380 :         if (autovacuum_vac_cost_limit > 0)
    1872           0 :             vacuum_cost_limit = autovacuum_vac_cost_limit;
    1873             :         else
    1874        1380 :             vacuum_cost_limit = VacuumCostLimit;
    1875             : 
    1876             :         /* Only balance limit if no cost-related storage parameters specified */
    1877        1380 :         if (pg_atomic_unlocked_test_flag(&MyWorkerInfo->wi_dobalance))
    1878           0 :             return;
    1879             : 
    1880             :         Assert(vacuum_cost_limit > 0);
    1881             : 
    1882        1380 :         nworkers_for_balance = pg_atomic_read_u32(&AutoVacuumShmem->av_nworkersForBalance);
    1883             : 
    1884             :         /* There is at least 1 autovac worker (this worker) */
    1885        1380 :         if (nworkers_for_balance <= 0)
    1886           0 :             elog(ERROR, "nworkers_for_balance must be > 0");
    1887             : 
    1888        1380 :         vacuum_cost_limit = Max(vacuum_cost_limit / nworkers_for_balance, 1);
    1889             :     }
    1890             : }
    1891             : 
    1892             : /*
    1893             :  * autovac_recalculate_workers_for_balance
    1894             :  *      Recalculate the number of workers to consider, given cost-related
    1895             :  *      storage parameters and the current number of active workers.
    1896             :  *
    1897             :  * Caller must hold the AutovacuumLock in at least shared mode to access
    1898             :  * worker->wi_proc.
    1899             :  */
    1900             : static void
    1901         366 : autovac_recalculate_workers_for_balance(void)
    1902             : {
    1903             :     dlist_iter  iter;
    1904             :     int         orig_nworkers_for_balance;
    1905         366 :     int         nworkers_for_balance = 0;
    1906             : 
    1907             :     Assert(LWLockHeldByMe(AutovacuumLock));
    1908             : 
    1909         366 :     orig_nworkers_for_balance =
    1910         366 :         pg_atomic_read_u32(&AutoVacuumShmem->av_nworkersForBalance);
    1911             : 
    1912         714 :     dlist_foreach(iter, &AutoVacuumShmem->av_runningWorkers)
    1913             :     {
    1914         348 :         WorkerInfo  worker = dlist_container(WorkerInfoData, wi_links, iter.cur);
    1915             : 
    1916         696 :         if (worker->wi_proc == NULL ||
    1917         348 :             pg_atomic_unlocked_test_flag(&worker->wi_dobalance))
    1918           0 :             continue;
    1919             : 
    1920         348 :         nworkers_for_balance++;
    1921             :     }
    1922             : 
    1923         366 :     if (nworkers_for_balance != orig_nworkers_for_balance)
    1924          32 :         pg_atomic_write_u32(&AutoVacuumShmem->av_nworkersForBalance,
    1925             :                             nworkers_for_balance);
    1926         366 : }
    1927             : 
    1928             : /*
    1929             :  * get_database_list
    1930             :  *      Return a list of all databases found in pg_database.
    1931             :  *
    1932             :  * The list and associated data is allocated in the caller's memory context,
    1933             :  * which is in charge of ensuring that it's properly cleaned up afterwards.
    1934             :  *
    1935             :  * Note: this is the only function in which the autovacuum launcher uses a
    1936             :  * transaction.  Although we aren't attached to any particular database and
    1937             :  * therefore can't access most catalogs, we do have enough infrastructure
    1938             :  * to do a seqscan on pg_database.
    1939             :  */
    1940             : static List *
    1941         732 : get_database_list(void)
    1942             : {
    1943         732 :     List       *dblist = NIL;
    1944             :     Relation    rel;
    1945             :     TableScanDesc scan;
    1946             :     HeapTuple   tup;
    1947             :     MemoryContext resultcxt;
    1948             : 
    1949             :     /* This is the context that we will allocate our output data in */
    1950         732 :     resultcxt = CurrentMemoryContext;
    1951             : 
    1952             :     /*
    1953             :      * Start a transaction so we can access pg_database, and get a snapshot.
    1954             :      * We don't have a use for the snapshot itself, but we're interested in
    1955             :      * the secondary effect that it sets RecentGlobalXmin.  (This is critical
    1956             :      * for anything that reads heap pages, because HOT may decide to prune
    1957             :      * them even if the process doesn't attempt to modify any tuples.)
    1958             :      *
    1959             :      * FIXME: This comment is inaccurate / the code buggy. A snapshot that is
    1960             :      * not pushed/active does not reliably prevent HOT pruning (->xmin could
    1961             :      * e.g. be cleared when cache invalidations are processed).
    1962             :      */
    1963         732 :     StartTransactionCommand();
    1964         732 :     (void) GetTransactionSnapshot();
    1965             : 
    1966         732 :     rel = table_open(DatabaseRelationId, AccessShareLock);
    1967         732 :     scan = table_beginscan_catalog(rel, 0, NULL);
    1968             : 
    1969        3260 :     while (HeapTupleIsValid(tup = heap_getnext(scan, ForwardScanDirection)))
    1970             :     {
    1971        2528 :         Form_pg_database pgdatabase = (Form_pg_database) GETSTRUCT(tup);
    1972             :         avw_dbase  *avdb;
    1973             :         MemoryContext oldcxt;
    1974             : 
    1975             :         /*
    1976             :          * Allocate our results in the caller's context, not the
    1977             :          * transaction's. We do this inside the loop, and restore the original
    1978             :          * context at the end, so that leaky things like heap_getnext() are
    1979             :          * not called in a potentially long-lived context.
    1980             :          */
    1981        2528 :         oldcxt = MemoryContextSwitchTo(resultcxt);
    1982             : 
    1983        2528 :         avdb = (avw_dbase *) palloc(sizeof(avw_dbase));
    1984             : 
    1985        2528 :         avdb->adw_datid = pgdatabase->oid;
    1986        2528 :         avdb->adw_name = pstrdup(NameStr(pgdatabase->datname));
    1987        2528 :         avdb->adw_frozenxid = pgdatabase->datfrozenxid;
    1988        2528 :         avdb->adw_minmulti = pgdatabase->datminmxid;
    1989             :         /* this gets set later: */
    1990        2528 :         avdb->adw_entry = NULL;
    1991             : 
    1992        2528 :         dblist = lappend(dblist, avdb);
    1993        2528 :         MemoryContextSwitchTo(oldcxt);
    1994             :     }
    1995             : 
    1996         732 :     table_endscan(scan);
    1997         732 :     table_close(rel, AccessShareLock);
    1998             : 
    1999         732 :     CommitTransactionCommand();
    2000             : 
    2001             :     /* Be sure to restore caller's memory context */
    2002         732 :     MemoryContextSwitchTo(resultcxt);
    2003             : 
    2004         732 :     return dblist;
    2005             : }
    2006             : 
    2007             : /*
    2008             :  * Process a database table-by-table
    2009             :  *
    2010             :  * Note that CHECK_FOR_INTERRUPTS is supposed to be used in certain spots in
    2011             :  * order not to ignore shutdown commands for too long.
    2012             :  */
    2013             : static void
    2014          18 : do_autovacuum(void)
    2015             : {
    2016             :     Relation    classRel;
    2017             :     HeapTuple   tuple;
    2018             :     TableScanDesc relScan;
    2019             :     Form_pg_database dbForm;
    2020          18 :     List       *table_oids = NIL;
    2021          18 :     List       *orphan_oids = NIL;
    2022             :     HASHCTL     ctl;
    2023             :     HTAB       *table_toast_map;
    2024             :     ListCell   *volatile cell;
    2025             :     BufferAccessStrategy bstrategy;
    2026             :     ScanKeyData key;
    2027             :     TupleDesc   pg_class_desc;
    2028             :     int         effective_multixact_freeze_max_age;
    2029          18 :     bool        did_vacuum = false;
    2030          18 :     bool        found_concurrent_worker = false;
    2031             :     int         i;
    2032             : 
    2033             :     /*
    2034             :      * StartTransactionCommand and CommitTransactionCommand will automatically
    2035             :      * switch to other contexts.  We need this one to keep the list of
    2036             :      * relations to vacuum/analyze across transactions.
    2037             :      */
    2038          18 :     AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,
    2039             :                                           "Autovacuum worker",
    2040             :                                           ALLOCSET_DEFAULT_SIZES);
    2041          18 :     MemoryContextSwitchTo(AutovacMemCxt);
    2042             : 
    2043             :     /* Start a transaction so our commands have one to play into. */
    2044          18 :     StartTransactionCommand();
    2045             : 
    2046             :     /*
    2047             :      * Compute the multixact age for which freezing is urgent.  This is
    2048             :      * normally autovacuum_multixact_freeze_max_age, but may be less if we are
    2049             :      * short of multixact member space.
    2050             :      */
    2051          18 :     effective_multixact_freeze_max_age = MultiXactMemberFreezeThreshold();
    2052             : 
    2053             :     /*
    2054             :      * Find the pg_database entry and select the default freeze ages. We use
    2055             :      * zero in template and nonconnectable databases, else the system-wide
    2056             :      * default.
    2057             :      */
    2058          18 :     tuple = SearchSysCache1(DATABASEOID, ObjectIdGetDatum(MyDatabaseId));
    2059          18 :     if (!HeapTupleIsValid(tuple))
    2060           0 :         elog(ERROR, "cache lookup failed for database %u", MyDatabaseId);
    2061          18 :     dbForm = (Form_pg_database) GETSTRUCT(tuple);
    2062             : 
    2063          18 :     if (dbForm->datistemplate || !dbForm->datallowconn)
    2064             :     {
    2065           4 :         default_freeze_min_age = 0;
    2066           4 :         default_freeze_table_age = 0;
    2067           4 :         default_multixact_freeze_min_age = 0;
    2068           4 :         default_multixact_freeze_table_age = 0;
    2069             :     }
    2070             :     else
    2071             :     {
    2072          14 :         default_freeze_min_age = vacuum_freeze_min_age;
    2073          14 :         default_freeze_table_age = vacuum_freeze_table_age;
    2074          14 :         default_multixact_freeze_min_age = vacuum_multixact_freeze_min_age;
    2075          14 :         default_multixact_freeze_table_age = vacuum_multixact_freeze_table_age;
    2076             :     }
    2077             : 
    2078          18 :     ReleaseSysCache(tuple);
    2079             : 
    2080             :     /* StartTransactionCommand changed elsewhere */
    2081          18 :     MemoryContextSwitchTo(AutovacMemCxt);
    2082             : 
    2083          18 :     classRel = table_open(RelationRelationId, AccessShareLock);
    2084             : 
    2085             :     /* create a copy so we can use it after closing pg_class */
    2086          18 :     pg_class_desc = CreateTupleDescCopy(RelationGetDescr(classRel));
    2087             : 
    2088             :     /* create hash table for toast <-> main relid mapping */
    2089          18 :     ctl.keysize = sizeof(Oid);
    2090          18 :     ctl.entrysize = sizeof(av_relation);
    2091             : 
    2092          18 :     table_toast_map = hash_create("TOAST to main relid map",
    2093             :                                   100,
    2094             :                                   &ctl,
    2095             :                                   HASH_ELEM | HASH_BLOBS);
    2096             : 
    2097             :     /*
    2098             :      * Scan pg_class to determine which tables to vacuum.
    2099             :      *
    2100             :      * We do this in two passes: on the first one we collect the list of plain
    2101             :      * relations and materialized views, and on the second one we collect
    2102             :      * TOAST tables. The reason for doing the second pass is that during it we
    2103             :      * want to use the main relation's pg_class.reloptions entry if the TOAST
    2104             :      * table does not have any, and we cannot obtain it unless we know
    2105             :      * beforehand what's the main table OID.
    2106             :      *
    2107             :      * We need to check TOAST tables separately because in cases with short,
    2108             :      * wide tables there might be proportionally much more activity in the
    2109             :      * TOAST table than in its parent.
    2110             :      */
    2111          18 :     relScan = table_beginscan_catalog(classRel, 0, NULL);
    2112             : 
    2113             :     /*
    2114             :      * On the first pass, we collect main tables to vacuum, and also the main
    2115             :      * table relid to TOAST relid mapping.
    2116             :      */
    2117       10274 :     while ((tuple = heap_getnext(relScan, ForwardScanDirection)) != NULL)
    2118             :     {
    2119       10256 :         Form_pg_class classForm = (Form_pg_class) GETSTRUCT(tuple);
    2120             :         PgStat_StatTabEntry *tabentry;
    2121             :         AutoVacOpts *relopts;
    2122             :         Oid         relid;
    2123             :         bool        dovacuum;
    2124             :         bool        doanalyze;
    2125             :         bool        wraparound;
    2126             : 
    2127       10256 :         if (classForm->relkind != RELKIND_RELATION &&
    2128        7944 :             classForm->relkind != RELKIND_MATVIEW)
    2129        7916 :             continue;
    2130             : 
    2131        2340 :         relid = classForm->oid;
    2132             : 
    2133             :         /*
    2134             :          * Check if it is a temp table (presumably, of some other backend's).
    2135             :          * We cannot safely process other backends' temp tables.
    2136             :          */
    2137        2340 :         if (classForm->relpersistence == RELPERSISTENCE_TEMP)
    2138             :         {
    2139             :             /*
    2140             :              * We just ignore it if the owning backend is still active and
    2141             :              * using the temporary schema.  Also, for safety, ignore it if the
    2142             :              * namespace doesn't exist or isn't a temp namespace after all.
    2143             :              */
    2144           0 :             if (checkTempNamespaceStatus(classForm->relnamespace) == TEMP_NAMESPACE_IDLE)
    2145             :             {
    2146             :                 /*
    2147             :                  * The table seems to be orphaned -- although it might be that
    2148             :                  * the owning backend has already deleted it and exited; our
    2149             :                  * pg_class scan snapshot is not necessarily up-to-date
    2150             :                  * anymore, so we could be looking at a committed-dead entry.
    2151             :                  * Remember it so we can try to delete it later.
    2152             :                  */
    2153           0 :                 orphan_oids = lappend_oid(orphan_oids, relid);
    2154             :             }
    2155           0 :             continue;
    2156             :         }
    2157             : 
    2158             :         /* Fetch reloptions and the pgstat entry for this table */
    2159        2340 :         relopts = extract_autovac_opts(tuple, pg_class_desc);
    2160        2340 :         tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
    2161             :                                                   relid);
    2162             : 
    2163             :         /* Check if it needs vacuum or analyze */
    2164        2340 :         relation_needs_vacanalyze(relid, relopts, classForm, tabentry,
    2165             :                                   effective_multixact_freeze_max_age,
    2166             :                                   &dovacuum, &doanalyze, &wraparound);
    2167             : 
    2168             :         /* Relations that need work are added to table_oids */
    2169        2340 :         if (dovacuum || doanalyze)
    2170         360 :             table_oids = lappend_oid(table_oids, relid);
    2171             : 
    2172             :         /*
    2173             :          * Remember TOAST associations for the second pass.  Note: we must do
    2174             :          * this whether or not the table is going to be vacuumed, because we
    2175             :          * don't automatically vacuum toast tables along the parent table.
    2176             :          */
    2177        2340 :         if (OidIsValid(classForm->reltoastrelid))
    2178             :         {
    2179             :             av_relation *hentry;
    2180             :             bool        found;
    2181             : 
    2182        2420 :             hentry = hash_search(table_toast_map,
    2183        1210 :                                  &classForm->reltoastrelid,
    2184             :                                  HASH_ENTER, &found);
    2185             : 
    2186        1210 :             if (!found)
    2187             :             {
    2188             :                 /* hash_search already filled in the key */
    2189        1210 :                 hentry->ar_relid = relid;
    2190        1210 :                 hentry->ar_hasrelopts = false;
    2191        1210 :                 if (relopts != NULL)
    2192             :                 {
    2193          36 :                     hentry->ar_hasrelopts = true;
    2194          36 :                     memcpy(&hentry->ar_reloptions, relopts,
    2195             :                            sizeof(AutoVacOpts));
    2196             :                 }
    2197             :             }
    2198             :         }
    2199             :     }
    2200             : 
    2201          18 :     table_endscan(relScan);
    2202             : 
    2203             :     /* second pass: check TOAST tables */
    2204          18 :     ScanKeyInit(&key,
    2205             :                 Anum_pg_class_relkind,
    2206             :                 BTEqualStrategyNumber, F_CHAREQ,
    2207             :                 CharGetDatum(RELKIND_TOASTVALUE));
    2208             : 
    2209          18 :     relScan = table_beginscan_catalog(classRel, 1, &key);
    2210        1228 :     while ((tuple = heap_getnext(relScan, ForwardScanDirection)) != NULL)
    2211             :     {
    2212        1210 :         Form_pg_class classForm = (Form_pg_class) GETSTRUCT(tuple);
    2213             :         PgStat_StatTabEntry *tabentry;
    2214             :         Oid         relid;
    2215        1210 :         AutoVacOpts *relopts = NULL;
    2216             :         bool        dovacuum;
    2217             :         bool        doanalyze;
    2218             :         bool        wraparound;
    2219             : 
    2220             :         /*
    2221             :          * We cannot safely process other backends' temp tables, so skip 'em.
    2222             :          */
    2223        1210 :         if (classForm->relpersistence == RELPERSISTENCE_TEMP)
    2224           0 :             continue;
    2225             : 
    2226        1210 :         relid = classForm->oid;
    2227             : 
    2228             :         /*
    2229             :          * fetch reloptions -- if this toast table does not have them, try the
    2230             :          * main rel
    2231             :          */
    2232        1210 :         relopts = extract_autovac_opts(tuple, pg_class_desc);
    2233        1210 :         if (relopts == NULL)
    2234             :         {
    2235             :             av_relation *hentry;
    2236             :             bool        found;
    2237             : 
    2238        1210 :             hentry = hash_search(table_toast_map, &relid, HASH_FIND, &found);
    2239        1210 :             if (found && hentry->ar_hasrelopts)
    2240          36 :                 relopts = &hentry->ar_reloptions;
    2241             :         }
    2242             : 
    2243             :         /* Fetch the pgstat entry for this table */
    2244        1210 :         tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
    2245             :                                                   relid);
    2246             : 
    2247        1210 :         relation_needs_vacanalyze(relid, relopts, classForm, tabentry,
    2248             :                                   effective_multixact_freeze_max_age,
    2249             :                                   &dovacuum, &doanalyze, &wraparound);
    2250             : 
    2251             :         /* ignore analyze for toast tables */
    2252        1210 :         if (dovacuum)
    2253           4 :             table_oids = lappend_oid(table_oids, relid);
    2254             :     }
    2255             : 
    2256          18 :     table_endscan(relScan);
    2257          18 :     table_close(classRel, AccessShareLock);
    2258             : 
    2259             :     /*
    2260             :      * Recheck orphan temporary tables, and if they still seem orphaned, drop
    2261             :      * them.  We'll eat a transaction per dropped table, which might seem
    2262             :      * excessive, but we should only need to do anything as a result of a
    2263             :      * previous backend crash, so this should not happen often enough to
    2264             :      * justify "optimizing".  Using separate transactions ensures that we
    2265             :      * don't bloat the lock table if there are many temp tables to be dropped,
    2266             :      * and it ensures that we don't lose work if a deletion attempt fails.
    2267             :      */
    2268          18 :     foreach(cell, orphan_oids)
    2269             :     {
    2270           0 :         Oid         relid = lfirst_oid(cell);
    2271             :         Form_pg_class classForm;
    2272             :         ObjectAddress object;
    2273             : 
    2274             :         /*
    2275             :          * Check for user-requested abort.
    2276             :          */
    2277           0 :         CHECK_FOR_INTERRUPTS();
    2278             : 
    2279             :         /*
    2280             :          * Try to lock the table.  If we can't get the lock immediately,
    2281             :          * somebody else is using (or dropping) the table, so it's not our
    2282             :          * concern anymore.  Having the lock prevents race conditions below.
    2283             :          */
    2284           0 :         if (!ConditionalLockRelationOid(relid, AccessExclusiveLock))
    2285           0 :             continue;
    2286             : 
    2287             :         /*
    2288             :          * Re-fetch the pg_class tuple and re-check whether it still seems to
    2289             :          * be an orphaned temp table.  If it's not there or no longer the same
    2290             :          * relation, ignore it.
    2291             :          */
    2292           0 :         tuple = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relid));
    2293           0 :         if (!HeapTupleIsValid(tuple))
    2294             :         {
    2295             :             /* be sure to drop useless lock so we don't bloat lock table */
    2296           0 :             UnlockRelationOid(relid, AccessExclusiveLock);
    2297           0 :             continue;
    2298             :         }
    2299           0 :         classForm = (Form_pg_class) GETSTRUCT(tuple);
    2300             : 
    2301             :         /*
    2302             :          * Make all the same tests made in the loop above.  In event of OID
    2303             :          * counter wraparound, the pg_class entry we have now might be
    2304             :          * completely unrelated to the one we saw before.
    2305             :          */
    2306           0 :         if (!((classForm->relkind == RELKIND_RELATION ||
    2307           0 :                classForm->relkind == RELKIND_MATVIEW) &&
    2308           0 :               classForm->relpersistence == RELPERSISTENCE_TEMP))
    2309             :         {
    2310           0 :             UnlockRelationOid(relid, AccessExclusiveLock);
    2311           0 :             continue;
    2312             :         }
    2313             : 
    2314           0 :         if (checkTempNamespaceStatus(classForm->relnamespace) != TEMP_NAMESPACE_IDLE)
    2315             :         {
    2316           0 :             UnlockRelationOid(relid, AccessExclusiveLock);
    2317           0 :             continue;
    2318             :         }
    2319             : 
    2320             :         /* OK, let's delete it */
    2321           0 :         ereport(LOG,
    2322             :                 (errmsg("autovacuum: dropping orphan temp table \"%s.%s.%s\"",
    2323             :                         get_database_name(MyDatabaseId),
    2324             :                         get_namespace_name(classForm->relnamespace),
    2325             :                         NameStr(classForm->relname))));
    2326             : 
    2327           0 :         object.classId = RelationRelationId;
    2328           0 :         object.objectId = relid;
    2329           0 :         object.objectSubId = 0;
    2330           0 :         performDeletion(&object, DROP_CASCADE,
    2331             :                         PERFORM_DELETION_INTERNAL |
    2332             :                         PERFORM_DELETION_QUIETLY |
    2333             :                         PERFORM_DELETION_SKIP_EXTENSIONS);
    2334             : 
    2335             :         /*
    2336             :          * To commit the deletion, end current transaction and start a new
    2337             :          * one.  Note this also releases the lock we took.
    2338             :          */
    2339           0 :         CommitTransactionCommand();
    2340           0 :         StartTransactionCommand();
    2341             : 
    2342             :         /* StartTransactionCommand changed current memory context */
    2343           0 :         MemoryContextSwitchTo(AutovacMemCxt);
    2344             :     }
    2345             : 
    2346             :     /*
    2347             :      * Optionally, create a buffer access strategy object for VACUUM to use.
    2348             :      * We use the same BufferAccessStrategy object for all tables VACUUMed by
    2349             :      * this worker to prevent autovacuum from blowing out shared buffers.
    2350             :      *
    2351             :      * VacuumBufferUsageLimit being set to 0 results in
    2352             :      * GetAccessStrategyWithSize returning NULL, effectively meaning we can
    2353             :      * use up to all of shared buffers.
    2354             :      *
    2355             :      * If we later enter failsafe mode on any of the tables being vacuumed, we
    2356             :      * will cease use of the BufferAccessStrategy only for that table.
    2357             :      *
    2358             :      * XXX should we consider adding code to adjust the size of this if
    2359             :      * VacuumBufferUsageLimit changes?
    2360             :      */
    2361          18 :     bstrategy = GetAccessStrategyWithSize(BAS_VACUUM, VacuumBufferUsageLimit);
    2362             : 
    2363             :     /*
    2364             :      * create a memory context to act as fake PortalContext, so that the
    2365             :      * contexts created in the vacuum code are cleaned up for each table.
    2366             :      */
    2367          18 :     PortalContext = AllocSetContextCreate(AutovacMemCxt,
    2368             :                                           "Autovacuum Portal",
    2369             :                                           ALLOCSET_DEFAULT_SIZES);
    2370             : 
    2371             :     /*
    2372             :      * Perform operations on collected tables.
    2373             :      */
    2374         382 :     foreach(cell, table_oids)
    2375             :     {
    2376         364 :         Oid         relid = lfirst_oid(cell);
    2377             :         HeapTuple   classTup;
    2378             :         autovac_table *tab;
    2379             :         bool        isshared;
    2380             :         bool        skipit;
    2381             :         dlist_iter  iter;
    2382             : 
    2383         364 :         CHECK_FOR_INTERRUPTS();
    2384             : 
    2385             :         /*
    2386             :          * Check for config changes before processing each collected table.
    2387             :          */
    2388         364 :         if (ConfigReloadPending)
    2389             :         {
    2390           0 :             ConfigReloadPending = false;
    2391           0 :             ProcessConfigFile(PGC_SIGHUP);
    2392             : 
    2393             :             /*
    2394             :              * You might be tempted to bail out if we see autovacuum is now
    2395             :              * disabled.  Must resist that temptation -- this might be a
    2396             :              * for-wraparound emergency worker, in which case that would be
    2397             :              * entirely inappropriate.
    2398             :              */
    2399             :         }
    2400             : 
    2401             :         /*
    2402             :          * Find out whether the table is shared or not.  (It's slightly
    2403             :          * annoying to fetch the syscache entry just for this, but in typical
    2404             :          * cases it adds little cost because table_recheck_autovac would
    2405             :          * refetch the entry anyway.  We could buy that back by copying the
    2406             :          * tuple here and passing it to table_recheck_autovac, but that
    2407             :          * increases the odds of that function working with stale data.)
    2408             :          */
    2409         364 :         classTup = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
    2410         364 :         if (!HeapTupleIsValid(classTup))
    2411          16 :             continue;           /* somebody deleted the rel, forget it */
    2412         364 :         isshared = ((Form_pg_class) GETSTRUCT(classTup))->relisshared;
    2413         364 :         ReleaseSysCache(classTup);
    2414             : 
    2415             :         /*
    2416             :          * Hold schedule lock from here until we've claimed the table.  We
    2417             :          * also need the AutovacuumLock to walk the worker array, but that one
    2418             :          * can just be a shared lock.
    2419             :          */
    2420         364 :         LWLockAcquire(AutovacuumScheduleLock, LW_EXCLUSIVE);
    2421         364 :         LWLockAcquire(AutovacuumLock, LW_SHARED);
    2422             : 
    2423             :         /*
    2424             :          * Check whether the table is being vacuumed concurrently by another
    2425             :          * worker.
    2426             :          */
    2427         364 :         skipit = false;
    2428         728 :         dlist_foreach(iter, &AutoVacuumShmem->av_runningWorkers)
    2429             :         {
    2430         364 :             WorkerInfo  worker = dlist_container(WorkerInfoData, wi_links, iter.cur);
    2431             : 
    2432             :             /* ignore myself */
    2433         364 :             if (worker == MyWorkerInfo)
    2434         364 :                 continue;
    2435             : 
    2436             :             /* ignore workers in other databases (unless table is shared) */
    2437           0 :             if (!worker->wi_sharedrel && worker->wi_dboid != MyDatabaseId)
    2438           0 :                 continue;
    2439             : 
    2440           0 :             if (worker->wi_tableoid == relid)
    2441             :             {
    2442           0 :                 skipit = true;
    2443           0 :                 found_concurrent_worker = true;
    2444           0 :                 break;
    2445             :             }
    2446             :         }
    2447         364 :         LWLockRelease(AutovacuumLock);
    2448         364 :         if (skipit)
    2449             :         {
    2450           0 :             LWLockRelease(AutovacuumScheduleLock);
    2451           0 :             continue;
    2452             :         }
    2453             : 
    2454             :         /*
    2455             :          * Store the table's OID in shared memory before releasing the
    2456             :          * schedule lock, so that other workers don't try to vacuum it
    2457             :          * concurrently.  (We claim it here so as not to hold
    2458             :          * AutovacuumScheduleLock while rechecking the stats.)
    2459             :          */
    2460         364 :         MyWorkerInfo->wi_tableoid = relid;
    2461         364 :         MyWorkerInfo->wi_sharedrel = isshared;
    2462         364 :         LWLockRelease(AutovacuumScheduleLock);
    2463             : 
    2464             :         /*
    2465             :          * Check whether pgstat data still says we need to vacuum this table.
    2466             :          * It could have changed if something else processed the table while
    2467             :          * we weren't looking. This doesn't entirely close the race condition,
    2468             :          * but it is very small.
    2469             :          */
    2470         364 :         MemoryContextSwitchTo(AutovacMemCxt);
    2471         364 :         tab = table_recheck_autovac(relid, table_toast_map, pg_class_desc,
    2472             :                                     effective_multixact_freeze_max_age);
    2473         364 :         if (tab == NULL)
    2474             :         {
    2475             :             /* someone else vacuumed the table, or it went away */
    2476          16 :             LWLockAcquire(AutovacuumScheduleLock, LW_EXCLUSIVE);
    2477          16 :             MyWorkerInfo->wi_tableoid = InvalidOid;
    2478          16 :             MyWorkerInfo->wi_sharedrel = false;
    2479          16 :             LWLockRelease(AutovacuumScheduleLock);
    2480          16 :             continue;
    2481             :         }
    2482             : 
    2483             :         /*
    2484             :          * Save the cost-related storage parameter values in global variables
    2485             :          * for reference when updating vacuum_cost_delay and vacuum_cost_limit
    2486             :          * during vacuuming this table.
    2487             :          */
    2488         348 :         av_storage_param_cost_delay = tab->at_storage_param_vac_cost_delay;
    2489         348 :         av_storage_param_cost_limit = tab->at_storage_param_vac_cost_limit;
    2490             : 
    2491             :         /*
    2492             :          * We only expect this worker to ever set the flag, so don't bother
    2493             :          * checking the return value. We shouldn't have to retry.
    2494             :          */
    2495         348 :         if (tab->at_dobalance)
    2496         348 :             pg_atomic_test_set_flag(&MyWorkerInfo->wi_dobalance);
    2497             :         else
    2498           0 :             pg_atomic_clear_flag(&MyWorkerInfo->wi_dobalance);
    2499             : 
    2500         348 :         LWLockAcquire(AutovacuumLock, LW_SHARED);
    2501         348 :         autovac_recalculate_workers_for_balance();
    2502         348 :         LWLockRelease(AutovacuumLock);
    2503             : 
    2504             :         /*
    2505             :          * We wait until this point to update cost delay and cost limit
    2506             :          * values, even though we reloaded the configuration file above, so
    2507             :          * that we can take into account the cost-related storage parameters.
    2508             :          */
    2509         348 :         VacuumUpdateCosts();
    2510             : 
    2511             : 
    2512             :         /* clean up memory before each iteration */
    2513         348 :         MemoryContextResetAndDeleteChildren(PortalContext);
    2514             : 
    2515             :         /*
    2516             :          * Save the relation name for a possible error message, to avoid a
    2517             :          * catalog lookup in case of an error.  If any of these return NULL,
    2518             :          * then the relation has been dropped since last we checked; skip it.
    2519             :          * Note: they must live in a long-lived memory context because we call
    2520             :          * vacuum and analyze in different transactions.
    2521             :          */
    2522             : 
    2523         348 :         tab->at_relname = get_rel_name(tab->at_relid);
    2524         348 :         tab->at_nspname = get_namespace_name(get_rel_namespace(tab->at_relid));
    2525         348 :         tab->at_datname = get_database_name(MyDatabaseId);
    2526         348 :         if (!tab->at_relname || !tab->at_nspname || !tab->at_datname)
    2527           0 :             goto deleted;
    2528             : 
    2529             :         /*
    2530             :          * We will abort vacuuming the current table if something errors out,
    2531             :          * and continue with the next one in schedule; in particular, this
    2532             :          * happens if we are interrupted with SIGINT.
    2533             :          */
    2534         348 :         PG_TRY();
    2535             :         {
    2536             :             /* Use PortalContext for any per-table allocations */
    2537         348 :             MemoryContextSwitchTo(PortalContext);
    2538             : 
    2539             :             /* have at it */
    2540         348 :             autovacuum_do_vac_analyze(tab, bstrategy);
    2541             : 
    2542             :             /*
    2543             :              * Clear a possible query-cancel signal, to avoid a late reaction
    2544             :              * to an automatically-sent signal because of vacuuming the
    2545             :              * current table (we're done with it, so it would make no sense to
    2546             :              * cancel at this point.)
    2547             :              */
    2548         348 :             QueryCancelPending = false;
    2549             :         }
    2550           0 :         PG_CATCH();
    2551             :         {
    2552             :             /*
    2553             :              * Abort the transaction, start a new one, and proceed with the
    2554             :              * next table in our list.
    2555             :              */
    2556           0 :             HOLD_INTERRUPTS();
    2557           0 :             if (tab->at_params.options & VACOPT_VACUUM)
    2558           0 :                 errcontext("automatic vacuum of table \"%s.%s.%s\"",
    2559             :                            tab->at_datname, tab->at_nspname, tab->at_relname);
    2560             :             else
    2561           0 :                 errcontext("automatic analyze of table \"%s.%s.%s\"",
    2562             :                            tab->at_datname, tab->at_nspname, tab->at_relname);
    2563           0 :             EmitErrorReport();
    2564             : 
    2565             :             /* this resets ProcGlobal->statusFlags[i] too */
    2566           0 :             AbortOutOfAnyTransaction();
    2567           0 :             FlushErrorState();
    2568           0 :             MemoryContextResetAndDeleteChildren(PortalContext);
    2569             : 
    2570             :             /* restart our transaction for the following operations */
    2571           0 :             StartTransactionCommand();
    2572           0 :             RESUME_INTERRUPTS();
    2573             :         }
    2574         348 :         PG_END_TRY();
    2575             : 
    2576             :         /* Make sure we're back in AutovacMemCxt */
    2577         348 :         MemoryContextSwitchTo(AutovacMemCxt);
    2578             : 
    2579         348 :         did_vacuum = true;
    2580             : 
    2581             :         /* ProcGlobal->statusFlags[i] are reset at the next end of xact */
    2582             : 
    2583             :         /* be tidy */
    2584         348 : deleted:
    2585         348 :         if (tab->at_datname != NULL)
    2586         348 :             pfree(tab->at_datname);
    2587         348 :         if (tab->at_nspname != NULL)
    2588         348 :             pfree(tab->at_nspname);
    2589         348 :         if (tab->at_relname != NULL)
    2590         348 :             pfree(tab->at_relname);
    2591         348 :         pfree(tab);
    2592             : 
    2593             :         /*
    2594             :          * Remove my info from shared memory.  We set wi_dobalance on the
    2595             :          * assumption that we are more likely than not to vacuum a table with
    2596             :          * no cost-related storage parameters next, so we want to claim our
    2597             :          * share of I/O as soon as possible to avoid thrashing the global
    2598             :          * balance.
    2599             :          */
    2600         348 :         LWLockAcquire(AutovacuumScheduleLock, LW_EXCLUSIVE);
    2601         348 :         MyWorkerInfo->wi_tableoid = InvalidOid;
    2602         348 :         MyWorkerInfo->wi_sharedrel = false;
    2603         348 :         LWLockRelease(AutovacuumScheduleLock);
    2604         348 :         pg_atomic_test_set_flag(&MyWorkerInfo->wi_dobalance);
    2605             :     }
    2606             : 
    2607             :     /*
    2608             :      * Perform additional work items, as requested by backends.
    2609             :      */
    2610          18 :     LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    2611        4626 :     for (i = 0; i < NUM_WORKITEMS; i++)
    2612             :     {
    2613        4608 :         AutoVacuumWorkItem *workitem = &AutoVacuumShmem->av_workItems[i];
    2614             : 
    2615        4608 :         if (!workitem->avw_used)
    2616        4602 :             continue;
    2617           6 :         if (workitem->avw_active)
    2618           0 :             continue;
    2619           6 :         if (workitem->avw_database != MyDatabaseId)
    2620           0 :             continue;
    2621             : 
    2622             :         /* claim this one, and release lock while performing it */
    2623           6 :         workitem->avw_active = true;
    2624           6 :         LWLockRelease(AutovacuumLock);
    2625             : 
    2626           6 :         perform_work_item(workitem);
    2627             : 
    2628             :         /*
    2629             :          * Check for config changes before acquiring lock for further jobs.
    2630             :          */
    2631           6 :         CHECK_FOR_INTERRUPTS();
    2632           6 :         if (ConfigReloadPending)
    2633             :         {
    2634           0 :             ConfigReloadPending = false;
    2635           0 :             ProcessConfigFile(PGC_SIGHUP);
    2636           0 :             VacuumUpdateCosts();
    2637             :         }
    2638             : 
    2639           6 :         LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    2640             : 
    2641             :         /* and mark it done */
    2642           6 :         workitem->avw_active = false;
    2643           6 :         workitem->avw_used = false;
    2644             :     }
    2645          18 :     LWLockRelease(AutovacuumLock);
    2646             : 
    2647             :     /*
    2648             :      * We leak table_toast_map here (among other things), but since we're
    2649             :      * going away soon, it's not a problem.
    2650             :      */
    2651             : 
    2652             :     /*
    2653             :      * Update pg_database.datfrozenxid, and truncate pg_xact if possible. We
    2654             :      * only need to do this once, not after each table.
    2655             :      *
    2656             :      * Even if we didn't vacuum anything, it may still be important to do
    2657             :      * this, because one indirect effect of vac_update_datfrozenxid() is to
    2658             :      * update ShmemVariableCache->xidVacLimit.  That might need to be done
    2659             :      * even if we haven't vacuumed anything, because relations with older
    2660             :      * relfrozenxid values or other databases with older datfrozenxid values
    2661             :      * might have been dropped, allowing xidVacLimit to advance.
    2662             :      *
    2663             :      * However, it's also important not to do this blindly in all cases,
    2664             :      * because when autovacuum=off this will restart the autovacuum launcher.
    2665             :      * If we're not careful, an infinite loop can result, where workers find
    2666             :      * no work to do and restart the launcher, which starts another worker in
    2667             :      * the same database that finds no work to do.  To prevent that, we skip
    2668             :      * this if (1) we found no work to do and (2) we skipped at least one
    2669             :      * table due to concurrent autovacuum activity.  In that case, the other
    2670             :      * worker has already done it, or will do so when it finishes.
    2671             :      */
    2672          18 :     if (did_vacuum || !found_concurrent_worker)
    2673          18 :         vac_update_datfrozenxid();
    2674             : 
    2675             :     /* Finally close out the last transaction. */
    2676          18 :     CommitTransactionCommand();
    2677          18 : }
    2678             : 
    2679             : /*
    2680             :  * Execute a previously registered work item.
    2681             :  */
    2682             : static void
    2683           6 : perform_work_item(AutoVacuumWorkItem *workitem)
    2684             : {
    2685           6 :     char       *cur_datname = NULL;
    2686           6 :     char       *cur_nspname = NULL;
    2687           6 :     char       *cur_relname = NULL;
    2688             : 
    2689             :     /*
    2690             :      * Note we do not store table info in MyWorkerInfo, since this is not
    2691             :      * vacuuming proper.
    2692             :      */
    2693             : 
    2694             :     /*
    2695             :      * Save the relation name for a possible error message, to avoid a catalog
    2696             :      * lookup in case of an error.  If any of these return NULL, then the
    2697             :      * relation has been dropped since last we checked; skip it.
    2698             :      */
    2699             :     Assert(CurrentMemoryContext == AutovacMemCxt);
    2700             : 
    2701           6 :     cur_relname = get_rel_name(workitem->avw_relation);
    2702           6 :     cur_nspname = get_namespace_name(get_rel_namespace(workitem->avw_relation));
    2703           6 :     cur_datname = get_database_name(MyDatabaseId);
    2704           6 :     if (!cur_relname || !cur_nspname || !cur_datname)
    2705           0 :         goto deleted2;
    2706             : 
    2707           6 :     autovac_report_workitem(workitem, cur_nspname, cur_relname);
    2708             : 
    2709             :     /* clean up memory before each work item */
    2710           6 :     MemoryContextResetAndDeleteChildren(PortalContext);
    2711             : 
    2712             :     /*
    2713             :      * We will abort the current work item if something errors out, and
    2714             :      * continue with the next one; in particular, this happens if we are
    2715             :      * interrupted with SIGINT.  Note that this means that the work item list
    2716             :      * can be lossy.
    2717             :      */
    2718           6 :     PG_TRY();
    2719             :     {
    2720             :         /* Use PortalContext for any per-work-item allocations */
    2721           6 :         MemoryContextSwitchTo(PortalContext);
    2722             : 
    2723             :         /*
    2724             :          * Have at it.  Functions called here are responsible for any required
    2725             :          * user switch and sandbox.
    2726             :          */
    2727           6 :         switch (workitem->avw_type)
    2728             :         {
    2729           6 :             case AVW_BRINSummarizeRange:
    2730           6 :                 DirectFunctionCall2(brin_summarize_range,
    2731             :                                     ObjectIdGetDatum(workitem->avw_relation),
    2732             :                                     Int64GetDatum((int64) workitem->avw_blockNumber));
    2733           6 :                 break;
    2734           0 :             default:
    2735           0 :                 elog(WARNING, "unrecognized work item found: type %d",
    2736             :                      workitem->avw_type);
    2737           0 :                 break;
    2738             :         }
    2739             : 
    2740             :         /*
    2741             :          * Clear a possible query-cancel signal, to avoid a late reaction to
    2742             :          * an automatically-sent signal because of vacuuming the current table
    2743             :          * (we're done with it, so it would make no sense to cancel at this
    2744             :          * point.)
    2745             :          */
    2746           6 :         QueryCancelPending = false;
    2747             :     }
    2748           0 :     PG_CATCH();
    2749             :     {
    2750             :         /*
    2751             :          * Abort the transaction, start a new one, and proceed with the next
    2752             :          * table in our list.
    2753             :          */
    2754           0 :         HOLD_INTERRUPTS();
    2755           0 :         errcontext("processing work entry for relation \"%s.%s.%s\"",
    2756             :                    cur_datname, cur_nspname, cur_relname);
    2757           0 :         EmitErrorReport();
    2758             : 
    2759             :         /* this resets ProcGlobal->statusFlags[i] too */
    2760           0 :         AbortOutOfAnyTransaction();
    2761           0 :         FlushErrorState();
    2762           0 :         MemoryContextResetAndDeleteChildren(PortalContext);
    2763             : 
    2764             :         /* restart our transaction for the following operations */
    2765           0 :         StartTransactionCommand();
    2766           0 :         RESUME_INTERRUPTS();
    2767             :     }
    2768           6 :     PG_END_TRY();
    2769             : 
    2770             :     /* Make sure we're back in AutovacMemCxt */
    2771           6 :     MemoryContextSwitchTo(AutovacMemCxt);
    2772             : 
    2773             :     /* We intentionally do not set did_vacuum here */
    2774             : 
    2775             :     /* be tidy */
    2776           6 : deleted2:
    2777           6 :     if (cur_datname)
    2778           6 :         pfree(cur_datname);
    2779           6 :     if (cur_nspname)
    2780           6 :         pfree(cur_nspname);
    2781           6 :     if (cur_relname)
    2782           6 :         pfree(cur_relname);
    2783           6 : }
    2784             : 
    2785             : /*
    2786             :  * extract_autovac_opts
    2787             :  *
    2788             :  * Given a relation's pg_class tuple, return the AutoVacOpts portion of
    2789             :  * reloptions, if set; otherwise, return NULL.
    2790             :  *
    2791             :  * Note: callers do not have a relation lock on the table at this point,
    2792             :  * so the table could have been dropped, and its catalog rows gone, after
    2793             :  * we acquired the pg_class row.  If pg_class had a TOAST table, this would
    2794             :  * be a risk; fortunately, it doesn't.
    2795             :  */
    2796             : static AutoVacOpts *
    2797        3914 : extract_autovac_opts(HeapTuple tup, TupleDesc pg_class_desc)
    2798             : {
    2799             :     bytea      *relopts;
    2800             :     AutoVacOpts *av;
    2801             : 
    2802             :     Assert(((Form_pg_class) GETSTRUCT(tup))->relkind == RELKIND_RELATION ||
    2803             :            ((Form_pg_class) GETSTRUCT(tup))->relkind == RELKIND_MATVIEW ||
    2804             :            ((Form_pg_class) GETSTRUCT(tup))->relkind == RELKIND_TOASTVALUE);
    2805             : 
    2806        3914 :     relopts = extractRelOptions(tup, pg_class_desc, NULL);
    2807        3914 :     if (relopts == NULL)
    2808        3838 :         return NULL;
    2809             : 
    2810          76 :     av = palloc(sizeof(AutoVacOpts));
    2811          76 :     memcpy(av, &(((StdRdOptions *) relopts)->autovacuum), sizeof(AutoVacOpts));
    2812          76 :     pfree(relopts);
    2813             : 
    2814          76 :     return av;
    2815             : }
    2816             : 
    2817             : 
    2818             : /*
    2819             :  * table_recheck_autovac
    2820             :  *
    2821             :  * Recheck whether a table still needs vacuum or analyze.  Return value is a
    2822             :  * valid autovac_table pointer if it does, NULL otherwise.
    2823             :  *
    2824             :  * Note that the returned autovac_table does not have the name fields set.
    2825             :  */
    2826             : static autovac_table *
    2827         364 : table_recheck_autovac(Oid relid, HTAB *table_toast_map,
    2828             :                       TupleDesc pg_class_desc,
    2829             :                       int effective_multixact_freeze_max_age)
    2830             : {
    2831             :     Form_pg_class classForm;
    2832             :     HeapTuple   classTup;
    2833             :     bool        dovacuum;
    2834             :     bool        doanalyze;
    2835         364 :     autovac_table *tab = NULL;
    2836             :     bool        wraparound;
    2837             :     AutoVacOpts *avopts;
    2838             : 
    2839             :     /* fetch the relation's relcache entry */
    2840         364 :     classTup = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relid));
    2841         364 :     if (!HeapTupleIsValid(classTup))
    2842           0 :         return NULL;
    2843         364 :     classForm = (Form_pg_class) GETSTRUCT(classTup);
    2844             : 
    2845             :     /*
    2846             :      * Get the applicable reloptions.  If it is a TOAST table, try to get the
    2847             :      * main table reloptions if the toast table itself doesn't have.
    2848             :      */
    2849         364 :     avopts = extract_autovac_opts(classTup, pg_class_desc);
    2850         364 :     if (classForm->relkind == RELKIND_TOASTVALUE &&
    2851           4 :         avopts == NULL && table_toast_map != NULL)
    2852             :     {
    2853             :         av_relation *hentry;
    2854             :         bool        found;
    2855             : 
    2856           4 :         hentry = hash_search(table_toast_map, &relid, HASH_FIND, &found);
    2857           4 :         if (found && hentry->ar_hasrelopts)
    2858           0 :             avopts = &hentry->ar_reloptions;
    2859             :     }
    2860             : 
    2861         364 :     recheck_relation_needs_vacanalyze(relid, avopts, classForm,
    2862             :                                       effective_multixact_freeze_max_age,
    2863             :                                       &dovacuum, &doanalyze, &wraparound);
    2864             : 
    2865             :     /* OK, it needs something done */
    2866         364 :     if (doanalyze || dovacuum)
    2867             :     {
    2868             :         int         freeze_min_age;
    2869             :         int         freeze_table_age;
    2870             :         int         multixact_freeze_min_age;
    2871             :         int         multixact_freeze_table_age;
    2872             :         int         log_min_duration;
    2873             : 
    2874             :         /*
    2875             :          * Calculate the vacuum cost parameters and the freeze ages.  If there
    2876             :          * are options set in pg_class.reloptions, use them; in the case of a
    2877             :          * toast table, try the main table too.  Otherwise use the GUC
    2878             :          * defaults, autovacuum's own first and plain vacuum second.
    2879             :          */
    2880             : 
    2881             :         /* -1 in autovac setting means use log_autovacuum_min_duration */
    2882          10 :         log_min_duration = (avopts && avopts->log_min_duration >= 0)
    2883             :             ? avopts->log_min_duration
    2884         358 :             : Log_autovacuum_min_duration;
    2885             : 
    2886             :         /* these do not have autovacuum-specific settings */
    2887          10 :         freeze_min_age = (avopts && avopts->freeze_min_age >= 0)
    2888             :             ? avopts->freeze_min_age
    2889         358 :             : default_freeze_min_age;
    2890             : 
    2891          10 :         freeze_table_age = (avopts && avopts->freeze_table_age >= 0)
    2892             :             ? avopts->freeze_table_age
    2893         358 :             : default_freeze_table_age;
    2894             : 
    2895         358 :         multixact_freeze_min_age = (avopts &&
    2896          10 :                                     avopts->multixact_freeze_min_age >= 0)
    2897             :             ? avopts->multixact_freeze_min_age
    2898         358 :             : default_multixact_freeze_min_age;
    2899             : 
    2900         358 :         multixact_freeze_table_age = (avopts &&
    2901          10 :                                       avopts->multixact_freeze_table_age >= 0)
    2902             :             ? avopts->multixact_freeze_table_age
    2903         358 :             : default_multixact_freeze_table_age;
    2904             : 
    2905         348 :         tab = palloc(sizeof(autovac_table));
    2906         348 :         tab->at_relid = relid;
    2907         348 :         tab->at_sharedrel = classForm->relisshared;
    2908             : 
    2909             :         /*
    2910             :          * Select VACUUM options.  Note we don't say VACOPT_PROCESS_TOAST, so
    2911             :          * that vacuum() skips toast relations.  Also note we tell vacuum() to
    2912             :          * skip vac_update_datfrozenxid(); we'll do that separately.
    2913             :          */
    2914         348 :         tab->at_params.options =
    2915         348 :             (dovacuum ? (VACOPT_VACUUM |
    2916             :                          VACOPT_PROCESS_MAIN |
    2917         348 :                          VACOPT_SKIP_DATABASE_STATS) : 0) |
    2918         348 :             (doanalyze ? VACOPT_ANALYZE : 0) |
    2919         348 :             (!wraparound ? VACOPT_SKIP_LOCKED : 0);
    2920             : 
    2921             :         /*
    2922             :          * index_cleanup and truncate are unspecified at first in autovacuum.
    2923             :          * They will be filled in with usable values using their reloptions
    2924             :          * (or reloption defaults) later.
    2925             :          */
    2926         348 :         tab->at_params.index_cleanup = VACOPTVALUE_UNSPECIFIED;
    2927         348 :         tab->at_params.truncate = VACOPTVALUE_UNSPECIFIED;
    2928             :         /* As of now, we don't support parallel vacuum for autovacuum */
    2929         348 :         tab->at_params.nworkers = -1;
    2930         348 :         tab->at_params.freeze_min_age = freeze_min_age;
    2931         348 :         tab->at_params.freeze_table_age = freeze_table_age;
    2932         348 :         tab->at_params.multixact_freeze_min_age = multixact_freeze_min_age;
    2933         348 :         tab->at_params.multixact_freeze_table_age = multixact_freeze_table_age;
    2934         348 :         tab->at_params.is_wraparound = wraparound;
    2935         348 :         tab->at_params.log_min_duration = log_min_duration;
    2936         348 :         tab->at_storage_param_vac_cost_limit = avopts ?
    2937         348 :             avopts->vacuum_cost_limit : 0;
    2938         348 :         tab->at_storage_param_vac_cost_delay = avopts ?
    2939         348 :             avopts->vacuum_cost_delay : -1;
    2940         348 :         tab->at_relname = NULL;
    2941         348 :         tab->at_nspname = NULL;
    2942         348 :         tab->at_datname = NULL;
    2943             : 
    2944             :         /*
    2945             :          * If any of the cost delay parameters has been set individually for
    2946             :          * this table, disable the balancing algorithm.
    2947             :          */
    2948         348 :         tab->at_dobalance =
    2949         358 :             !(avopts && (avopts->vacuum_cost_limit > 0 ||
    2950          10 :                          avopts->vacuum_cost_delay >= 0));
    2951             :     }
    2952             : 
    2953         364 :     heap_freetuple(classTup);
    2954         364 :     return tab;
    2955             : }
    2956             : 
    2957             : /*
    2958             :  * recheck_relation_needs_vacanalyze
    2959             :  *
    2960             :  * Subroutine for table_recheck_autovac.
    2961             :  *
    2962             :  * Fetch the pgstat of a relation and recheck whether a relation
    2963             :  * needs to be vacuumed or analyzed.
    2964             :  */
    2965             : static void
    2966         364 : recheck_relation_needs_vacanalyze(Oid relid,
    2967             :                                   AutoVacOpts *avopts,
    2968             :                                   Form_pg_class classForm,
    2969             :                                   int effective_multixact_freeze_max_age,
    2970             :                                   bool *dovacuum,
    2971             :                                   bool *doanalyze,
    2972             :                                   bool *wraparound)
    2973             : {
    2974             :     PgStat_StatTabEntry *tabentry;
    2975             : 
    2976             :     /* fetch the pgstat table entry */
    2977         364 :     tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
    2978             :                                               relid);
    2979             : 
    2980         364 :     relation_needs_vacanalyze(relid, avopts, classForm, tabentry,
    2981             :                               effective_multixact_freeze_max_age,
    2982             :                               dovacuum, doanalyze, wraparound);
    2983             : 
    2984             :     /* ignore ANALYZE for toast tables */
    2985         364 :     if (classForm->relkind == RELKIND_TOASTVALUE)
    2986           4 :         *doanalyze = false;
    2987         364 : }
    2988             : 
    2989             : /*
    2990             :  * relation_needs_vacanalyze
    2991             :  *
    2992             :  * Check whether a relation needs to be vacuumed or analyzed; return each into
    2993             :  * "dovacuum" and "doanalyze", respectively.  Also return whether the vacuum is
    2994             :  * being forced because of Xid or multixact wraparound.
    2995             :  *
    2996             :  * relopts is a pointer to the AutoVacOpts options (either for itself in the
    2997             :  * case of a plain table, or for either itself or its parent table in the case
    2998             :  * of a TOAST table), NULL if none; tabentry is the pgstats entry, which can be
    2999             :  * NULL.
    3000             :  *
    3001             :  * A table needs to be vacuumed if the number of dead tuples exceeds a
    3002             :  * threshold.  This threshold is calculated as
    3003             :  *
    3004             :  * threshold = vac_base_thresh + vac_scale_factor * reltuples
    3005             :  *
    3006             :  * For analyze, the analysis done is that the number of tuples inserted,
    3007             :  * deleted and updated since the last analyze exceeds a threshold calculated
    3008             :  * in the same fashion as above.  Note that the cumulative stats system stores
    3009             :  * the number of tuples (both live and dead) that there were as of the last
    3010             :  * analyze.  This is asymmetric to the VACUUM case.
    3011             :  *
    3012             :  * We also force vacuum if the table's relfrozenxid is more than freeze_max_age
    3013             :  * transactions back, and if its relminmxid is more than
    3014             :  * multixact_freeze_max_age multixacts back.
    3015             :  *
    3016             :  * A table whose autovacuum_enabled option is false is
    3017             :  * automatically skipped (unless we have to vacuum it due to freeze_max_age).
    3018             :  * Thus autovacuum can be disabled for specific tables. Also, when the cumulative
    3019             :  * stats system does not have data about a table, it will be skipped.
    3020             :  *
    3021             :  * A table whose vac_base_thresh value is < 0 takes the base value from the
    3022             :  * autovacuum_vacuum_threshold GUC variable.  Similarly, a vac_scale_factor
    3023             :  * value < 0 is substituted with the value of
    3024             :  * autovacuum_vacuum_scale_factor GUC variable.  Ditto for analyze.
    3025             :  */
    3026             : static void
    3027        3914 : relation_needs_vacanalyze(Oid relid,
    3028             :                           AutoVacOpts *relopts,
    3029             :                           Form_pg_class classForm,
    3030             :                           PgStat_StatTabEntry *tabentry,
    3031             :                           int effective_multixact_freeze_max_age,
    3032             :  /* output params below */
    3033             :                           bool *dovacuum,
    3034             :                           bool *doanalyze,
    3035             :                           bool *wraparound)
    3036             : {
    3037             :     bool        force_vacuum;
    3038             :     bool        av_enabled;
    3039             :     float4      reltuples;      /* pg_class.reltuples */
    3040             : 
    3041             :     /* constants from reloptions or GUC variables */
    3042             :     int         vac_base_thresh,
    3043             :                 vac_ins_base_thresh,
    3044             :                 anl_base_thresh;
    3045             :     float4      vac_scale_factor,
    3046             :                 vac_ins_scale_factor,
    3047             :                 anl_scale_factor;
    3048             : 
    3049             :     /* thresholds calculated from above constants */
    3050             :     float4      vacthresh,
    3051             :                 vacinsthresh,
    3052             :                 anlthresh;
    3053             : 
    3054             :     /* number of vacuum (resp. analyze) tuples at this time */
    3055             :     float4      vactuples,
    3056             :                 instuples,
    3057             :                 anltuples;
    3058             : 
    3059             :     /* freeze parameters */
    3060             :     int         freeze_max_age;
    3061             :     int         multixact_freeze_max_age;
    3062             :     TransactionId xidForceLimit;
    3063             :     MultiXactId multiForceLimit;
    3064             : 
    3065             :     Assert(classForm != NULL);
    3066             :     Assert(OidIsValid(relid));
    3067             : 
    3068             :     /*
    3069             :      * Determine vacuum/analyze equation parameters.  We have two possible
    3070             :      * sources: the passed reloptions (which could be a main table or a toast
    3071             :      * table), or the autovacuum GUC variables.
    3072             :      */
    3073             : 
    3074             :     /* -1 in autovac setting means use plain vacuum_scale_factor */
    3075         112 :     vac_scale_factor = (relopts && relopts->vacuum_scale_factor >= 0)
    3076           0 :         ? relopts->vacuum_scale_factor
    3077        4026 :         : autovacuum_vac_scale;
    3078             : 
    3079         112 :     vac_base_thresh = (relopts && relopts->vacuum_threshold >= 0)
    3080             :         ? relopts->vacuum_threshold
    3081        4026 :         : autovacuum_vac_thresh;
    3082             : 
    3083         112 :     vac_ins_scale_factor = (relopts && relopts->vacuum_ins_scale_factor >= 0)
    3084           0 :         ? relopts->vacuum_ins_scale_factor
    3085        4026 :         : autovacuum_vac_ins_scale;
    3086             : 
    3087             :     /* -1 is used to disable insert vacuums */
    3088         112 :     vac_ins_base_thresh = (relopts && relopts->vacuum_ins_threshold >= -1)
    3089             :         ? relopts->vacuum_ins_threshold
    3090        4026 :         : autovacuum_vac_ins_thresh;
    3091             : 
    3092         112 :     anl_scale_factor = (relopts && relopts->analyze_scale_factor >= 0)
    3093           0 :         ? relopts->analyze_scale_factor
    3094        4026 :         : autovacuum_anl_scale;
    3095             : 
    3096         112 :     anl_base_thresh = (relopts && relopts->analyze_threshold >= 0)
    3097             :         ? relopts->analyze_threshold
    3098        4026 :         : autovacuum_anl_thresh;
    3099             : 
    3100         112 :     freeze_max_age = (relopts && relopts->freeze_max_age >= 0)
    3101           0 :         ? Min(relopts->freeze_max_age, autovacuum_freeze_max_age)
    3102        4026 :         : autovacuum_freeze_max_age;
    3103             : 
    3104         112 :     multixact_freeze_max_age = (relopts && relopts->multixact_freeze_max_age >= 0)
    3105           0 :         ? Min(relopts->multixact_freeze_max_age, effective_multixact_freeze_max_age)
    3106        4026 :         : effective_multixact_freeze_max_age;
    3107             : 
    3108        3914 :     av_enabled = (relopts ? relopts->enabled : true);
    3109             : 
    3110             :     /* Force vacuum if table is at risk of wraparound */
    3111        3914 :     xidForceLimit = recentXid - freeze_max_age;
    3112        3914 :     if (xidForceLimit < FirstNormalTransactionId)
    3113           0 :         xidForceLimit -= FirstNormalTransactionId;
    3114        7828 :     force_vacuum = (TransactionIdIsNormal(classForm->relfrozenxid) &&
    3115        3914 :                     TransactionIdPrecedes(classForm->relfrozenxid,
    3116             :                                           xidForceLimit));
    3117        3914 :     if (!force_vacuum)
    3118             :     {
    3119        3914 :         multiForceLimit = recentMulti - multixact_freeze_max_age;
    3120        3914 :         if (multiForceLimit < FirstMultiXactId)
    3121           0 :             multiForceLimit -= FirstMultiXactId;
    3122        7828 :         force_vacuum = MultiXactIdIsValid(classForm->relminmxid) &&
    3123        3914 :             MultiXactIdPrecedes(classForm->relminmxid, multiForceLimit);
    3124             :     }
    3125        3914 :     *wraparound = force_vacuum;
    3126             : 
    3127             :     /* User disabled it in pg_class.reloptions?  (But ignore if at risk) */
    3128        3914 :     if (!av_enabled && !force_vacuum)
    3129             :     {
    3130          76 :         *doanalyze = false;
    3131          76 :         *dovacuum = false;
    3132          76 :         return;
    3133             :     }
    3134             : 
    3135             :     /*
    3136             :      * If we found stats for the table, and autovacuum is currently enabled,
    3137             :      * make a threshold-based decision whether to vacuum and/or analyze.  If
    3138             :      * autovacuum is currently disabled, we must be here for anti-wraparound
    3139             :      * vacuuming only, so don't vacuum (or analyze) anything that's not being
    3140             :      * forced.
    3141             :      */
    3142        3838 :     if (PointerIsValid(tabentry) && AutoVacuumingActive())
    3143             :     {
    3144        3030 :         reltuples = classForm->reltuples;
    3145        3030 :         vactuples = tabentry->dead_tuples;
    3146        3030 :         instuples = tabentry->ins_since_vacuum;
    3147        3030 :         anltuples = tabentry->mod_since_analyze;
    3148             : 
    3149             :         /* If the table hasn't yet been vacuumed, take reltuples as zero */
    3150        3030 :         if (reltuples < 0)
    3151         658 :             reltuples = 0;
    3152             : 
    3153        3030 :         vacthresh = (float4) vac_base_thresh + vac_scale_factor * reltuples;
    3154        3030 :         vacinsthresh = (float4) vac_ins_base_thresh + vac_ins_scale_factor * reltuples;
    3155        3030 :         anlthresh = (float4) anl_base_thresh + anl_scale_factor * reltuples;
    3156             : 
    3157             :         /*
    3158             :          * Note that we don't need to take special consideration for stat
    3159             :          * reset, because if that happens, the last vacuum and analyze counts
    3160             :          * will be reset too.
    3161             :          */
    3162        3030 :         if (vac_ins_base_thresh >= 0)
    3163        3030 :             elog(DEBUG3, "%s: vac: %.0f (threshold %.0f), ins: %.0f (threshold %.0f), anl: %.0f (threshold %.0f)",
    3164             :                  NameStr(classForm->relname),
    3165             :                  vactuples, vacthresh, instuples, vacinsthresh, anltuples, anlthresh);
    3166             :         else
    3167           0 :             elog(DEBUG3, "%s: vac: %.0f (threshold %.0f), ins: (disabled), anl: %.0f (threshold %.0f)",
    3168             :                  NameStr(classForm->relname),
    3169             :                  vactuples, vacthresh, anltuples, anlthresh);
    3170             : 
    3171             :         /* Determine if this table needs vacuum or analyze. */
    3172        5834 :         *dovacuum = force_vacuum || (vactuples > vacthresh) ||
    3173        2804 :             (vac_ins_base_thresh >= 0 && instuples > vacinsthresh);
    3174        3030 :         *doanalyze = (anltuples > anlthresh);
    3175             :     }
    3176             :     else
    3177             :     {
    3178             :         /*
    3179             :          * Skip a table not found in stat hash, unless we have to force vacuum
    3180             :          * for anti-wrap purposes.  If it's not acted upon, there's no need to
    3181             :          * vacuum it.
    3182             :          */
    3183         808 :         *dovacuum = force_vacuum;
    3184         808 :         *doanalyze = false;
    3185             :     }
    3186             : 
    3187             :     /* ANALYZE refuses to work with pg_statistic */
    3188        3838 :     if (relid == StatisticRelationId)
    3189          22 :         *doanalyze = false;
    3190             : }
    3191             : 
    3192             : /*
    3193             :  * autovacuum_do_vac_analyze
    3194             :  *      Vacuum and/or analyze the specified table
    3195             :  *
    3196             :  * We expect the caller to have switched into a memory context that won't
    3197             :  * disappear at transaction commit.
    3198             :  */
    3199             : static void
    3200         348 : autovacuum_do_vac_analyze(autovac_table *tab, BufferAccessStrategy bstrategy)
    3201             : {
    3202             :     RangeVar   *rangevar;
    3203             :     VacuumRelation *rel;
    3204             :     List       *rel_list;
    3205             :     MemoryContext vac_context;
    3206             : 
    3207             :     /* Let pgstat know what we're doing */
    3208         348 :     autovac_report_activity(tab);
    3209             : 
    3210             :     /* Set up one VacuumRelation target, identified by OID, for vacuum() */
    3211         348 :     rangevar = makeRangeVar(tab->at_nspname, tab->at_relname, -1);
    3212         348 :     rel = makeVacuumRelation(rangevar, tab->at_relid, NIL);
    3213         348 :     rel_list = list_make1(rel);
    3214             : 
    3215         348 :     vac_context = AllocSetContextCreate(CurrentMemoryContext,
    3216             :                                         "Vacuum",
    3217             :                                         ALLOCSET_DEFAULT_SIZES);
    3218             : 
    3219         348 :     vacuum(rel_list, &tab->at_params, bstrategy, vac_context, true);
    3220             : 
    3221         348 :     MemoryContextDelete(vac_context);
    3222         348 : }
    3223             : 
    3224             : /*
    3225             :  * autovac_report_activity
    3226             :  *      Report to pgstat what autovacuum is doing
    3227             :  *
    3228             :  * We send a SQL string corresponding to what the user would see if the
    3229             :  * equivalent command was to be issued manually.
    3230             :  *
    3231             :  * Note we assume that we are going to report the next command as soon as we're
    3232             :  * done with the current one, and exit right after the last one, so we don't
    3233             :  * bother to report "<IDLE>" or some such.
    3234             :  */
    3235             : static void
    3236         348 : autovac_report_activity(autovac_table *tab)
    3237             : {
    3238             : #define MAX_AUTOVAC_ACTIV_LEN (NAMEDATALEN * 2 + 56)
    3239             :     char        activity[MAX_AUTOVAC_ACTIV_LEN];
    3240             :     int         len;
    3241             : 
    3242             :     /* Report the command and possible options */
    3243         348 :     if (tab->at_params.options & VACOPT_VACUUM)
    3244         164 :         snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
    3245             :                  "autovacuum: VACUUM%s",
    3246         164 :                  tab->at_params.options & VACOPT_ANALYZE ? " ANALYZE" : "");
    3247             :     else
    3248         184 :         snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
    3249             :                  "autovacuum: ANALYZE");
    3250             : 
    3251             :     /*
    3252             :      * Report the qualified name of the relation.
    3253             :      */
    3254         348 :     len = strlen(activity);
    3255             : 
    3256         348 :     snprintf(activity + len, MAX_AUTOVAC_ACTIV_LEN - len,
    3257             :              " %s.%s%s", tab->at_nspname, tab->at_relname,
    3258         348 :              tab->at_params.is_wraparound ? " (to prevent wraparound)" : "");
    3259             : 
    3260             :     /* Set statement_timestamp() to current time for pg_stat_activity */
    3261         348 :     SetCurrentStatementStartTimestamp();
    3262             : 
    3263         348 :     pgstat_report_activity(STATE_RUNNING, activity);
    3264         348 : }
    3265             : 
    3266             : /*
    3267             :  * autovac_report_workitem
    3268             :  *      Report to pgstat that autovacuum is processing a work item
    3269             :  */
    3270             : static void
    3271           6 : autovac_report_workitem(AutoVacuumWorkItem *workitem,
    3272             :                         const char *nspname, const char *relname)
    3273             : {
    3274             :     char        activity[MAX_AUTOVAC_ACTIV_LEN + 12 + 2];
    3275             :     char        blk[12 + 2];
    3276             :     int         len;
    3277             : 
    3278           6 :     switch (workitem->avw_type)
    3279             :     {
    3280           6 :         case AVW_BRINSummarizeRange:
    3281           6 :             snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
    3282             :                      "autovacuum: BRIN summarize");
    3283           6 :             break;
    3284             :     }
    3285             : 
    3286             :     /*
    3287             :      * Report the qualified name of the relation, and the block number if any
    3288             :      */
    3289           6 :     len = strlen(activity);
    3290             : 
    3291           6 :     if (BlockNumberIsValid(workitem->avw_blockNumber))
    3292           6 :         snprintf(blk, sizeof(blk), " %u", workitem->avw_blockNumber);
    3293             :     else
    3294           0 :         blk[0] = '\0';
    3295             : 
    3296           6 :     snprintf(activity + len, MAX_AUTOVAC_ACTIV_LEN - len,
    3297             :              " %s.%s%s", nspname, relname, blk);
    3298             : 
    3299             :     /* Set statement_timestamp() to current time for pg_stat_activity */
    3300           6 :     SetCurrentStatementStartTimestamp();
    3301             : 
    3302           6 :     pgstat_report_activity(STATE_RUNNING, activity);
    3303           6 : }
    3304             : 
    3305             : /*
    3306             :  * AutoVacuumingActive
    3307             :  *      Check GUC vars and report whether the autovacuum process should be
    3308             :  *      running.
    3309             :  */
    3310             : bool
    3311       12584 : AutoVacuumingActive(void)
    3312             : {
    3313       12584 :     if (!autovacuum_start_daemon || !pgstat_track_counts)
    3314        2350 :         return false;
    3315       10234 :     return true;
    3316             : }
    3317             : 
    3318             : /*
    3319             :  * Request one work item to the next autovacuum run processing our database.
    3320             :  * Return false if the request can't be recorded.
    3321             :  */
    3322             : bool
    3323           6 : AutoVacuumRequestWork(AutoVacuumWorkItemType type, Oid relationId,
    3324             :                       BlockNumber blkno)
    3325             : {
    3326             :     int         i;
    3327           6 :     bool        result = false;
    3328             : 
    3329           6 :     LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
    3330             : 
    3331             :     /*
    3332             :      * Locate an unused work item and fill it with the given data.
    3333             :      */
    3334          12 :     for (i = 0; i < NUM_WORKITEMS; i++)
    3335             :     {
    3336          12 :         AutoVacuumWorkItem *workitem = &AutoVacuumShmem->av_workItems[i];
    3337             : 
    3338          12 :         if (workitem->avw_used)
    3339           6 :             continue;
    3340             : 
    3341           6 :         workitem->avw_used = true;
    3342           6 :         workitem->avw_active = false;
    3343           6 :         workitem->avw_type = type;
    3344           6 :         workitem->avw_database = MyDatabaseId;
    3345           6 :         workitem->avw_relation = relationId;
    3346           6 :         workitem->avw_blockNumber = blkno;
    3347           6 :         result = true;
    3348             : 
    3349             :         /* done */
    3350           6 :         break;
    3351             :     }
    3352             : 
    3353           6 :     LWLockRelease(AutovacuumLock);
    3354             : 
    3355           6 :     return result;
    3356             : }
    3357             : 
    3358             : /*
    3359             :  * autovac_init
    3360             :  *      This is called at postmaster initialization.
    3361             :  *
    3362             :  * All we do here is annoy the user if he got it wrong.
    3363             :  */
    3364             : void
    3365        1186 : autovac_init(void)
    3366             : {
    3367        1186 :     if (autovacuum_start_daemon && !pgstat_track_counts)
    3368           0 :         ereport(WARNING,
    3369             :                 (errmsg("autovacuum not started because of misconfiguration"),
    3370             :                  errhint("Enable the \"track_counts\" option.")));
    3371        1186 : }
    3372             : 
    3373             : /*
    3374             :  * IsAutoVacuum functions
    3375             :  *      Return whether this is either a launcher autovacuum process or a worker
    3376             :  *      process.
    3377             :  */
    3378             : bool
    3379       93070 : IsAutoVacuumLauncherProcess(void)
    3380             : {
    3381       93070 :     return am_autovacuum_launcher;
    3382             : }
    3383             : 
    3384             : bool
    3385      458682 : IsAutoVacuumWorkerProcess(void)
    3386             : {
    3387      458682 :     return am_autovacuum_worker;
    3388             : }
    3389             : 
    3390             : 
    3391             : /*
    3392             :  * AutoVacuumShmemSize
    3393             :  *      Compute space needed for autovacuum-related shared memory
    3394             :  */
    3395             : Size
    3396        9092 : AutoVacuumShmemSize(void)
    3397             : {
    3398             :     Size        size;
    3399             : 
    3400             :     /*
    3401             :      * Need the fixed struct and the array of WorkerInfoData.
    3402             :      */
    3403        9092 :     size = sizeof(AutoVacuumShmemStruct);
    3404        9092 :     size = MAXALIGN(size);
    3405        9092 :     size = add_size(size, mul_size(autovacuum_max_workers,
    3406             :                                    sizeof(WorkerInfoData)));
    3407        9092 :     return size;
    3408             : }
    3409             : 
    3410             : /*
    3411             :  * AutoVacuumShmemInit
    3412             :  *      Allocate and initialize autovacuum-related shared memory
    3413             :  */
    3414             : void
    3415        3636 : AutoVacuumShmemInit(void)
    3416             : {
    3417             :     bool        found;
    3418             : 
    3419        3636 :     AutoVacuumShmem = (AutoVacuumShmemStruct *)
    3420        3636 :         ShmemInitStruct("AutoVacuum Data",
    3421             :                         AutoVacuumShmemSize(),
    3422             :                         &found);
    3423             : 
    3424        3636 :     if (!IsUnderPostmaster)
    3425             :     {
    3426             :         WorkerInfo  worker;
    3427             :         int         i;
    3428             : 
    3429             :         Assert(!found);
    3430             : 
    3431        3636 :         AutoVacuumShmem->av_launcherpid = 0;
    3432        3636 :         dlist_init(&AutoVacuumShmem->av_freeWorkers);
    3433        3636 :         dlist_init(&AutoVacuumShmem->av_runningWorkers);
    3434        3636 :         AutoVacuumShmem->av_startingWorker = NULL;
    3435        3636 :         memset(AutoVacuumShmem->av_workItems, 0,
    3436             :                sizeof(AutoVacuumWorkItem) * NUM_WORKITEMS);
    3437             : 
    3438        3636 :         worker = (WorkerInfo) ((char *) AutoVacuumShmem +
    3439             :                                MAXALIGN(sizeof(AutoVacuumShmemStruct)));
    3440             : 
    3441             :         /* initialize the WorkerInfo free list */
    3442       14544 :         for (i = 0; i < autovacuum_max_workers; i++)
    3443             :         {
    3444       10908 :             dlist_push_head(&AutoVacuumShmem->av_freeWorkers,
    3445       10908 :                             &worker[i].wi_links);
    3446       10908 :             pg_atomic_init_flag(&worker[i].wi_dobalance);
    3447             :         }
    3448             : 
    3449        3636 :         pg_atomic_init_u32(&AutoVacuumShmem->av_nworkersForBalance, 0);
    3450             : 
    3451             :     }
    3452             :     else
    3453             :         Assert(found);
    3454        3636 : }
    3455             : 
    3456             : /*
    3457             :  * GUC check_hook for autovacuum_work_mem
    3458             :  */
    3459             : bool
    3460        3702 : check_autovacuum_work_mem(int *newval, void **extra, GucSource source)
    3461             : {
    3462             :     /*
    3463             :      * -1 indicates fallback.
    3464             :      *
    3465             :      * If we haven't yet changed the boot_val default of -1, just let it be.
    3466             :      * Autovacuum will look to maintenance_work_mem instead.
    3467             :      */
    3468        3702 :     if (*newval == -1)
    3469        3698 :         return true;
    3470             : 
    3471             :     /*
    3472             :      * We clamp manually-set values to at least 1MB.  Since
    3473             :      * maintenance_work_mem is always set to at least this value, do the same
    3474             :      * here.
    3475             :      */
    3476           4 :     if (*newval < 1024)
    3477           4 :         *newval = 1024;
    3478             : 
    3479           4 :     return true;
    3480             : }

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