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postgres/src/backend/postmaster/autovacuum.c
Heikki Linnakangas 7537f52a00 Utilize the visibility map in autovacuum, too. There was an oversight in 
the visibility map patch that because autovacuum always sets
VacuumStmt->freeze_min_age, visibility map was never used for autovacuum,
only for manually launched vacuums. This patch introduces a new scan_all
field to VacuumStmt, indicating explicitly whether the visibility map
should be used, or the whole relation should be scanned, to advance
relfrozenxid. Anti-wraparound vacuums still need to scan all pages.
2008-12-04 11:42:24 +00:00

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/*-------------------------------------------------------------------------
*
* autovacuum.c
*
* PostgreSQL Integrated Autovacuum Daemon
*
* The autovacuum system is structured in two different kinds of processes: the
* autovacuum launcher and the autovacuum worker. The launcher is an
* always-running process, started by the postmaster when the autovacuum GUC
* parameter is set. The launcher schedules autovacuum workers to be started
* when appropriate. The workers are the processes which execute the actual
* vacuuming; they connect to a database as determined in the launcher, and
* once connected they examine the catalogs to select the tables to vacuum.
*
* The autovacuum launcher cannot start the worker processes by itself,
* because doing so would cause robustness issues (namely, failure to shut
* them down on exceptional conditions, and also, since the launcher is
* connected to shared memory and is thus subject to corruption there, it is
* not as robust as the postmaster). So it leaves that task to the postmaster.
*
* There is an autovacuum shared memory area, where the launcher stores
* information about the database it wants vacuumed. When it wants a new
* worker to start, it sets a flag in shared memory and sends a signal to the
* postmaster. Then postmaster knows nothing more than it must start a worker;
* so it forks a new child, which turns into a worker. This new process
* connects to shared memory, and there it can inspect the information that the
* launcher has set up.
*
* If the fork() call fails in the postmaster, it sets a flag in the shared
* memory area, and sends a signal to the launcher. The launcher, upon
* noticing the flag, can try starting the worker again by resending the
* signal. Note that the failure can only be transient (fork failure due to
* high load, memory pressure, too many processes, etc); more permanent
* problems, like failure to connect to a database, are detected later in the
* worker and dealt with just by having the worker exit normally. The launcher
* will launch a new worker again later, per schedule.
*
* When the worker is done vacuuming it sends SIGUSR1 to the launcher. The
* launcher then wakes up and is able to launch another worker, if the schedule
* is so tight that a new worker is needed immediately. At this time the
* launcher can also balance the settings for the various remaining workers'
* cost-based vacuum delay feature.
*
* Note that there can be more than one worker in a database concurrently.
* They will store the table they are currently vacuuming in shared memory, so
* that other workers avoid being blocked waiting for the vacuum lock for that
* table. They will also reload the pgstats data just before vacuuming each
* table, to avoid vacuuming a table that was just finished being vacuumed by
* another worker and thus is no longer noted in shared memory. However,
* there is a window (caused by pgstat delay) on which a worker may choose a
* table that was already vacuumed; this is a bug in the current design.
*
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.88 2008/12/04 11:42:24 heikki Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <signal.h>
#include <sys/types.h>
#include <sys/time.h>
#include <time.h>
#include <unistd.h>
#include "access/genam.h"
#include "access/heapam.h"
#include "access/transam.h"
#include "access/xact.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/namespace.h"
#include "catalog/pg_autovacuum.h"
#include "catalog/pg_database.h"
#include "commands/dbcommands.h"
#include "commands/vacuum.h"
#include "libpq/hba.h"
#include "libpq/pqsignal.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "postmaster/autovacuum.h"
#include "postmaster/fork_process.h"
#include "postmaster/postmaster.h"
#include "storage/bufmgr.h"
#include "storage/fd.h"
#include "storage/ipc.h"
#include "storage/pmsignal.h"
#include "storage/proc.h"
#include "storage/procarray.h"
#include "storage/sinvaladt.h"
#include "tcop/tcopprot.h"
#include "utils/dynahash.h"
#include "utils/flatfiles.h"
#include "utils/fmgroids.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/ps_status.h"
#include "utils/syscache.h"
#include "utils/tqual.h"
/*
* GUC parameters
*/
bool autovacuum_start_daemon = false;
int autovacuum_max_workers;
int autovacuum_naptime;
int autovacuum_vac_thresh;
double autovacuum_vac_scale;
int autovacuum_anl_thresh;
double autovacuum_anl_scale;
int autovacuum_freeze_max_age;
int autovacuum_vac_cost_delay;
int autovacuum_vac_cost_limit;
int Log_autovacuum_min_duration = -1;
/* how long to keep pgstat data in the launcher, in milliseconds */
#define STATS_READ_DELAY 1000
/* Flags to tell if we are in an autovacuum process */
static bool am_autovacuum_launcher = false;
static bool am_autovacuum_worker = false;
/* Flags set by signal handlers */
static volatile sig_atomic_t got_SIGHUP = false;
static volatile sig_atomic_t got_SIGUSR1 = false;
static volatile sig_atomic_t got_SIGTERM = false;
/* Comparison point for determining whether freeze_max_age is exceeded */
static TransactionId recentXid;
/* Default freeze_min_age to use for autovacuum (varies by database) */
static int default_freeze_min_age;
/* Memory context for long-lived data */
static MemoryContext AutovacMemCxt;
/* struct to keep track of databases in launcher */
typedef struct avl_dbase
{
Oid adl_datid; /* hash key -- must be first */
TimestampTz adl_next_worker;
int adl_score;
} avl_dbase;
/* struct to keep track of databases in worker */
typedef struct avw_dbase
{
Oid adw_datid;
char *adw_name;
TransactionId adw_frozenxid;
PgStat_StatDBEntry *adw_entry;
} avw_dbase;
/* struct to keep track of tables to vacuum and/or analyze, in 1st pass */
typedef struct av_relation
{
Oid ar_toastrelid; /* hash key - must be first */
Oid ar_relid;
} av_relation;
/* struct to keep track of tables to vacuum and/or analyze, after rechecking */
typedef struct autovac_table
{
Oid at_relid;
Oid at_toastrelid;
bool at_dovacuum;
bool at_doanalyze;
int at_freeze_min_age;
int at_vacuum_cost_delay;
int at_vacuum_cost_limit;
bool at_wraparound;
char *at_relname;
char *at_nspname;
char *at_datname;
} autovac_table;
/*-------------
* This struct holds information about a single worker's whereabouts. We keep
* an array of these in shared memory, sized according to
* autovacuum_max_workers.
*
* wi_links entry into free list or running list
* wi_dboid OID of the database this worker is supposed to work on
* wi_tableoid OID of the table currently being vacuumed
* wi_proc pointer to PGPROC of the running worker, NULL if not started
* wi_launchtime Time at which this worker was launched
* wi_cost_* Vacuum cost-based delay parameters current in this worker
*
* All fields are protected by AutovacuumLock, except for wi_tableoid which is
* protected by AutovacuumScheduleLock (which is read-only for everyone except
* that worker itself).
*-------------
*/
typedef struct WorkerInfoData
{
SHM_QUEUE wi_links;
Oid wi_dboid;
Oid wi_tableoid;
PGPROC *wi_proc;
TimestampTz wi_launchtime;
int wi_cost_delay;
int wi_cost_limit;
int wi_cost_limit_base;
} WorkerInfoData;
typedef struct WorkerInfoData *WorkerInfo;
/*
* Possible signals received by the launcher from remote processes. These are
* stored atomically in shared memory so that other processes can set them
* without locking.
*/
typedef enum
{
AutoVacForkFailed, /* failed trying to start a worker */
AutoVacRebalance, /* rebalance the cost limits */
AutoVacNumSignals /* must be last */
} AutoVacuumSignal;
/*-------------
* The main autovacuum shmem struct. On shared memory we store this main
* struct and the array of WorkerInfo structs. This struct keeps:
*
* av_signal set by other processes to indicate various conditions
* av_launcherpid the PID of the autovacuum launcher
* av_freeWorkers the WorkerInfo freelist
* av_runningWorkers the WorkerInfo non-free queue
* av_startingWorker pointer to WorkerInfo currently being started (cleared by
* the worker itself as soon as it's up and running)
*
* This struct is protected by AutovacuumLock, except for av_signal and parts
* of the worker list (see above).
*-------------
*/
typedef struct
{
sig_atomic_t av_signal[AutoVacNumSignals];
pid_t av_launcherpid;
WorkerInfo av_freeWorkers;
SHM_QUEUE av_runningWorkers;
WorkerInfo av_startingWorker;
} AutoVacuumShmemStruct;
static AutoVacuumShmemStruct *AutoVacuumShmem;
/* the database list in the launcher, and the context that contains it */
static Dllist *DatabaseList = NULL;
static MemoryContext DatabaseListCxt = NULL;
/* Pointer to my own WorkerInfo, valid on each worker */
static WorkerInfo MyWorkerInfo = NULL;
/* PID of launcher, valid only in worker while shutting down */
int AutovacuumLauncherPid = 0;
#ifdef EXEC_BACKEND
static pid_t avlauncher_forkexec(void);
static pid_t avworker_forkexec(void);
#endif
NON_EXEC_STATIC void AutoVacWorkerMain(int argc, char *argv[]);
NON_EXEC_STATIC void AutoVacLauncherMain(int argc, char *argv[]);
static Oid do_start_worker(void);
static void launcher_determine_sleep(bool canlaunch, bool recursing,
struct timeval * nap);
static void launch_worker(TimestampTz now);
static List *get_database_list(void);
static void rebuild_database_list(Oid newdb);
static int db_comparator(const void *a, const void *b);
static void autovac_balance_cost(void);
static void do_autovacuum(void);
static void FreeWorkerInfo(int code, Datum arg);
static autovac_table *table_recheck_autovac(Oid relid, HTAB *table_toast_map);
static void relation_needs_vacanalyze(Oid relid, Form_pg_autovacuum avForm,
Form_pg_class classForm,
PgStat_StatTabEntry *tabentry, bool *dovacuum,
bool *doanalyze, bool *wraparound);
static void autovacuum_do_vac_analyze(autovac_table *tab,
BufferAccessStrategy bstrategy);
static HeapTuple get_pg_autovacuum_tuple_relid(Relation avRel, Oid relid,
HTAB *table_toast_map);
static PgStat_StatTabEntry *get_pgstat_tabentry_relid(Oid relid, bool isshared,
PgStat_StatDBEntry *shared,
PgStat_StatDBEntry *dbentry);
static void autovac_report_activity(autovac_table *tab);
static void avl_sighup_handler(SIGNAL_ARGS);
static void avl_sigusr1_handler(SIGNAL_ARGS);
static void avl_sigterm_handler(SIGNAL_ARGS);
static void avl_quickdie(SIGNAL_ARGS);
static void autovac_refresh_stats(void);
/********************************************************************
* AUTOVACUUM LAUNCHER CODE
********************************************************************/
#ifdef EXEC_BACKEND
/*
* forkexec routine for the autovacuum launcher process.
*
* Format up the arglist, then fork and exec.
*/
static pid_t
avlauncher_forkexec(void)
{
char *av[10];
int ac = 0;
av[ac++] = "postgres";
av[ac++] = "--forkavlauncher";
av[ac++] = NULL; /* filled in by postmaster_forkexec */
av[ac] = NULL;
Assert(ac < lengthof(av));
return postmaster_forkexec(ac, av);
}
/*
* We need this set from the outside, before InitProcess is called
*/
void
AutovacuumLauncherIAm(void)
{
am_autovacuum_launcher = true;
}
#endif
/*
* Main entry point for autovacuum launcher process, to be called from the
* postmaster.
*/
int
StartAutoVacLauncher(void)
{
pid_t AutoVacPID;
#ifdef EXEC_BACKEND
switch ((AutoVacPID = avlauncher_forkexec()))
#else
switch ((AutoVacPID = fork_process()))
#endif
{
case -1:
ereport(LOG,
(errmsg("could not fork autovacuum launcher process: %m")));
return 0;
#ifndef EXEC_BACKEND
case 0:
/* in postmaster child ... */
/* Close the postmaster's sockets */
ClosePostmasterPorts(false);
/* Lose the postmaster's on-exit routines */
on_exit_reset();
AutoVacLauncherMain(0, NULL);
break;
#endif
default:
return (int) AutoVacPID;
}
/* shouldn't get here */
return 0;
}
/*
* Main loop for the autovacuum launcher process.
*/
NON_EXEC_STATIC void
AutoVacLauncherMain(int argc, char *argv[])
{
sigjmp_buf local_sigjmp_buf;
/* we are a postmaster subprocess now */
IsUnderPostmaster = true;
am_autovacuum_launcher = true;
/* reset MyProcPid */
MyProcPid = getpid();
/* record Start Time for logging */
MyStartTime = time(NULL);
/* Identify myself via ps */
init_ps_display("autovacuum launcher process", "", "", "");
if (PostAuthDelay)
pg_usleep(PostAuthDelay * 1000000L);
SetProcessingMode(InitProcessing);
/*
* If possible, make this process a group leader, so that the postmaster
* can signal any child processes too. (autovacuum probably never has any
* child processes, but for consistency we make all postmaster child
* processes do this.)
*/
#ifdef HAVE_SETSID
if (setsid() < 0)
elog(FATAL, "setsid() failed: %m");
#endif
/*
* Set up signal handlers. Since this is an auxiliary process, it has
* particular signal requirements -- no deadlock checker or sinval
* catchup, for example.
*/
pqsignal(SIGHUP, avl_sighup_handler);
pqsignal(SIGINT, SIG_IGN);
pqsignal(SIGTERM, avl_sigterm_handler);
pqsignal(SIGQUIT, avl_quickdie);
pqsignal(SIGALRM, SIG_IGN);
pqsignal(SIGPIPE, SIG_IGN);
pqsignal(SIGUSR1, avl_sigusr1_handler);
/* We don't listen for async notifies */
pqsignal(SIGUSR2, SIG_IGN);
pqsignal(SIGFPE, FloatExceptionHandler);
pqsignal(SIGCHLD, SIG_DFL);
/* Early initialization */
BaseInit();
/*
* Create a per-backend PGPROC struct in shared memory, except in the
* EXEC_BACKEND case where this was done in SubPostmasterMain. We must do
* this before we can use LWLocks (and in the EXEC_BACKEND case we already
* had to do some stuff with LWLocks).
*/
#ifndef EXEC_BACKEND
InitAuxiliaryProcess();
#endif
/*
* Create a memory context that we will do all our work in. We do this so
* that we can reset the context during error recovery and thereby avoid
* possible memory leaks.
*/
AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,
"Autovacuum Launcher",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
MemoryContextSwitchTo(AutovacMemCxt);
/*
* If an exception is encountered, processing resumes here.
*
* This code is heavily based on bgwriter.c, q.v.
*/
if (sigsetjmp(local_sigjmp_buf, 1) != 0)
{
/* since not using PG_TRY, must reset error stack by hand */
error_context_stack = NULL;
/* Prevents interrupts while cleaning up */
HOLD_INTERRUPTS();
/* Report the error to the server log */
EmitErrorReport();
/*
* These operations are really just a minimal subset of
* AbortTransaction(). We don't have very many resources to worry
* about, but we do have LWLocks.
*/
LWLockReleaseAll();
AtEOXact_Files();
AtEOXact_HashTables(false);
/*
* Now return to normal top-level context and clear ErrorContext for
* next time.
*/
MemoryContextSwitchTo(AutovacMemCxt);
FlushErrorState();
/* Flush any leaked data in the top-level context */
MemoryContextResetAndDeleteChildren(AutovacMemCxt);
/* don't leave dangling pointers to freed memory */
DatabaseListCxt = NULL;
DatabaseList = NULL;
/*
* Make sure pgstat also considers our stat data as gone. Note: we
* mustn't use autovac_refresh_stats here.
*/
pgstat_clear_snapshot();
/* Now we can allow interrupts again */
RESUME_INTERRUPTS();
/*
* Sleep at least 1 second after any error. We don't want to be
* filling the error logs as fast as we can.
*/
pg_usleep(1000000L);
}
/* We can now handle ereport(ERROR) */
PG_exception_stack = &local_sigjmp_buf;
ereport(LOG,
(errmsg("autovacuum launcher started")));
/* must unblock signals before calling rebuild_database_list */
PG_SETMASK(&UnBlockSig);
/* in emergency mode, just start a worker and go away */
if (!AutoVacuumingActive())
{
do_start_worker();
proc_exit(0); /* done */
}
AutoVacuumShmem->av_launcherpid = MyProcPid;
/*
* Create the initial database list. The invariant we want this list to
* keep is that it's ordered by decreasing next_time. As soon as an entry
* is updated to a higher time, it will be moved to the front (which is
* correct because the only operation is to add autovacuum_naptime to the
* entry, and time always increases).
*/
rebuild_database_list(InvalidOid);
for (;;)
{
struct timeval nap;
TimestampTz current_time = 0;
bool can_launch;
Dlelem *elem;
/*
* Emergency bailout if postmaster has died. This is to avoid the
* necessity for manual cleanup of all postmaster children.
*/
if (!PostmasterIsAlive(true))
exit(1);
launcher_determine_sleep((AutoVacuumShmem->av_freeWorkers != NULL),
false, &nap);
/*
* Sleep for a while according to schedule.
*
* On some platforms, signals won't interrupt the sleep. To ensure we
* respond reasonably promptly when someone signals us, break down the
* sleep into 1-second increments, and check for interrupts after each
* nap.
*/
while (nap.tv_sec > 0 || nap.tv_usec > 0)
{
uint32 sleeptime;
if (nap.tv_sec > 0)
{
sleeptime = 1000000;
nap.tv_sec--;
}
else
{
sleeptime = nap.tv_usec;
nap.tv_usec = 0;
}
pg_usleep(sleeptime);
/*
* Emergency bailout if postmaster has died. This is to avoid the
* necessity for manual cleanup of all postmaster children.
*/
if (!PostmasterIsAlive(true))
exit(1);
if (got_SIGTERM || got_SIGHUP || got_SIGUSR1)
break;
}
/* the normal shutdown case */
if (got_SIGTERM)
break;
if (got_SIGHUP)
{
got_SIGHUP = false;
ProcessConfigFile(PGC_SIGHUP);
/* shutdown requested in config file */
if (!AutoVacuumingActive())
break;
/* rebalance in case the default cost parameters changed */
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
autovac_balance_cost();
LWLockRelease(AutovacuumLock);
/* rebuild the list in case the naptime changed */
rebuild_database_list(InvalidOid);
}
/*
* a worker finished, or postmaster signalled failure to start a
* worker
*/
if (got_SIGUSR1)
{
got_SIGUSR1 = false;
/* rebalance cost limits, if needed */
if (AutoVacuumShmem->av_signal[AutoVacRebalance])
{
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
AutoVacuumShmem->av_signal[AutoVacRebalance] = false;
autovac_balance_cost();
LWLockRelease(AutovacuumLock);
}
if (AutoVacuumShmem->av_signal[AutoVacForkFailed])
{
/*
* If the postmaster failed to start a new worker, we sleep
* for a little while and resend the signal. The new worker's
* state is still in memory, so this is sufficient. After
* that, we restart the main loop.
*
* XXX should we put a limit to the number of times we retry?
* I don't think it makes much sense, because a future start
* of a worker will continue to fail in the same way.
*/
AutoVacuumShmem->av_signal[AutoVacForkFailed] = false;
pg_usleep(100000L); /* 100ms */
SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER);
continue;
}
}
/*
* There are some conditions that we need to check before trying to
* start a launcher. First, we need to make sure that there is a
* launcher slot available. Second, we need to make sure that no
* other worker failed while starting up.
*/
current_time = GetCurrentTimestamp();
LWLockAcquire(AutovacuumLock, LW_SHARED);
can_launch = (AutoVacuumShmem->av_freeWorkers != NULL);
if (AutoVacuumShmem->av_startingWorker != NULL)
{
int waittime;
WorkerInfo worker = AutoVacuumShmem->av_startingWorker;
/*
* We can't launch another worker when another one is still
* starting up (or failed while doing so), so just sleep for a bit
* more; that worker will wake us up again as soon as it's ready.
* We will only wait autovacuum_naptime seconds (up to a maximum
* of 60 seconds) for this to happen however. Note that failure
* to connect to a particular database is not a problem here,
* because the worker removes itself from the startingWorker
* pointer before trying to connect. Problems detected by the
* postmaster (like fork() failure) are also reported and handled
* differently. The only problems that may cause this code to
* fire are errors in the earlier sections of AutoVacWorkerMain,
* before the worker removes the WorkerInfo from the
* startingWorker pointer.
*/
waittime = Min(autovacuum_naptime, 60) * 1000;
if (TimestampDifferenceExceeds(worker->wi_launchtime, current_time,
waittime))
{
LWLockRelease(AutovacuumLock);
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
/*
* No other process can put a worker in starting mode, so if
* startingWorker is still INVALID after exchanging our lock,
* we assume it's the same one we saw above (so we don't
* recheck the launch time).
*/
if (AutoVacuumShmem->av_startingWorker != NULL)
{
worker = AutoVacuumShmem->av_startingWorker;
worker->wi_dboid = InvalidOid;
worker->wi_tableoid = InvalidOid;
worker->wi_proc = NULL;
worker->wi_launchtime = 0;
worker->wi_links.next = (SHM_QUEUE *) AutoVacuumShmem->av_freeWorkers;
AutoVacuumShmem->av_freeWorkers = worker;
AutoVacuumShmem->av_startingWorker = NULL;
elog(WARNING, "worker took too long to start; cancelled");
}
}
else
can_launch = false;
}
LWLockRelease(AutovacuumLock); /* either shared or exclusive */
/* if we can't do anything, just go back to sleep */
if (!can_launch)
continue;
/* We're OK to start a new worker */
elem = DLGetTail(DatabaseList);
if (elem != NULL)
{
avl_dbase *avdb = DLE_VAL(elem);
/*
* launch a worker if next_worker is right now or it is in the
* past
*/
if (TimestampDifferenceExceeds(avdb->adl_next_worker,
current_time, 0))
launch_worker(current_time);
}
else
{
/*
* Special case when the list is empty: start a worker right away.
* This covers the initial case, when no database is in pgstats
* (thus the list is empty). Note that the constraints in
* launcher_determine_sleep keep us from starting workers too
* quickly (at most once every autovacuum_naptime when the list is
* empty).
*/
launch_worker(current_time);
}
}
/* Normal exit from the autovac launcher is here */
ereport(LOG,
(errmsg("autovacuum launcher shutting down")));
AutoVacuumShmem->av_launcherpid = 0;
proc_exit(0); /* done */
}
/*
* Determine the time to sleep, based on the database list.
*
* The "canlaunch" parameter indicates whether we can start a worker right now,
* for example due to the workers being all busy. If this is false, we will
* cause a long sleep, which will be interrupted when a worker exits.
*/
static void
launcher_determine_sleep(bool canlaunch, bool recursing, struct timeval * nap)
{
Dlelem *elem;
/*
* We sleep until the next scheduled vacuum. We trust that when the
* database list was built, care was taken so that no entries have times
* in the past; if the first entry has too close a next_worker value, or a
* time in the past, we will sleep a small nominal time.
*/
if (!canlaunch)
{
nap->tv_sec = autovacuum_naptime;
nap->tv_usec = 0;
}
else if ((elem = DLGetTail(DatabaseList)) != NULL)
{
avl_dbase *avdb = DLE_VAL(elem);
TimestampTz current_time = GetCurrentTimestamp();
TimestampTz next_wakeup;
long secs;
int usecs;
next_wakeup = avdb->adl_next_worker;
TimestampDifference(current_time, next_wakeup, &secs, &usecs);
nap->tv_sec = secs;
nap->tv_usec = usecs;
}
else
{
/* list is empty, sleep for whole autovacuum_naptime seconds */
nap->tv_sec = autovacuum_naptime;
nap->tv_usec = 0;
}
/*
* If the result is exactly zero, it means a database had an entry with
* time in the past. Rebuild the list so that the databases are evenly
* distributed again, and recalculate the time to sleep. This can happen
* if there are more tables needing vacuum than workers, and they all take
* longer to vacuum than autovacuum_naptime.
*
* We only recurse once. rebuild_database_list should always return times
* in the future, but it seems best not to trust too much on that.
*/
if (nap->tv_sec == 0 && nap->tv_usec == 0 && !recursing)
{
rebuild_database_list(InvalidOid);
launcher_determine_sleep(canlaunch, true, nap);
return;
}
/* 100ms is the smallest time we'll allow the launcher to sleep */
if (nap->tv_sec <= 0 && nap->tv_usec <= 100000)
{
nap->tv_sec = 0;
nap->tv_usec = 100000; /* 100 ms */
}
}
/*
* Build an updated DatabaseList. It must only contain databases that appear
* in pgstats, and must be sorted by next_worker from highest to lowest,
* distributed regularly across the next autovacuum_naptime interval.
*
* Receives the Oid of the database that made this list be generated (we call
* this the "new" database, because when the database was already present on
* the list, we expect that this function is not called at all). The
* preexisting list, if any, will be used to preserve the order of the
* databases in the autovacuum_naptime period. The new database is put at the
* end of the interval. The actual values are not saved, which should not be
* much of a problem.
*/
static void
rebuild_database_list(Oid newdb)
{
List *dblist;
ListCell *cell;
MemoryContext newcxt;
MemoryContext oldcxt;
MemoryContext tmpcxt;
HASHCTL hctl;
int score;
int nelems;
HTAB *dbhash;
/* use fresh stats */
autovac_refresh_stats();
newcxt = AllocSetContextCreate(AutovacMemCxt,
"AV dblist",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
tmpcxt = AllocSetContextCreate(newcxt,
"tmp AV dblist",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
oldcxt = MemoryContextSwitchTo(tmpcxt);
/*
* Implementing this is not as simple as it sounds, because we need to put
* the new database at the end of the list; next the databases that were
* already on the list, and finally (at the tail of the list) all the
* other databases that are not on the existing list.
*
* To do this, we build an empty hash table of scored databases. We will
* start with the lowest score (zero) for the new database, then
* increasing scores for the databases in the existing list, in order, and
* lastly increasing scores for all databases gotten via
* get_database_list() that are not already on the hash.
*
* Then we will put all the hash elements into an array, sort the array by
* score, and finally put the array elements into the new doubly linked
* list.
*/
hctl.keysize = sizeof(Oid);
hctl.entrysize = sizeof(avl_dbase);
hctl.hash = oid_hash;
hctl.hcxt = tmpcxt;
dbhash = hash_create("db hash", 20, &hctl, /* magic number here FIXME */
HASH_ELEM | HASH_FUNCTION | HASH_CONTEXT);
/* start by inserting the new database */
score = 0;
if (OidIsValid(newdb))
{
avl_dbase *db;
PgStat_StatDBEntry *entry;
/* only consider this database if it has a pgstat entry */
entry = pgstat_fetch_stat_dbentry(newdb);
if (entry != NULL)
{
/* we assume it isn't found because the hash was just created */
db = hash_search(dbhash, &newdb, HASH_ENTER, NULL);
/* hash_search already filled in the key */
db->adl_score = score++;
/* next_worker is filled in later */
}
}
/* Now insert the databases from the existing list */
if (DatabaseList != NULL)
{
Dlelem *elem;
elem = DLGetHead(DatabaseList);
while (elem != NULL)
{
avl_dbase *avdb = DLE_VAL(elem);
avl_dbase *db;
bool found;
PgStat_StatDBEntry *entry;
elem = DLGetSucc(elem);
/*
* skip databases with no stat entries -- in particular, this gets
* rid of dropped databases
*/
entry = pgstat_fetch_stat_dbentry(avdb->adl_datid);
if (entry == NULL)
continue;
db = hash_search(dbhash, &(avdb->adl_datid), HASH_ENTER, &found);
if (!found)
{
/* hash_search already filled in the key */
db->adl_score = score++;
/* next_worker is filled in later */
}
}
}
/* finally, insert all qualifying databases not previously inserted */
dblist = get_database_list();
foreach(cell, dblist)
{
avw_dbase *avdb = lfirst(cell);
avl_dbase *db;
bool found;
PgStat_StatDBEntry *entry;
/* only consider databases with a pgstat entry */
entry = pgstat_fetch_stat_dbentry(avdb->adw_datid);
if (entry == NULL)
continue;
db = hash_search(dbhash, &(avdb->adw_datid), HASH_ENTER, &found);
/* only update the score if the database was not already on the hash */
if (!found)
{
/* hash_search already filled in the key */
db->adl_score = score++;
/* next_worker is filled in later */
}
}
nelems = score;
/* from here on, the allocated memory belongs to the new list */
MemoryContextSwitchTo(newcxt);
DatabaseList = DLNewList();
if (nelems > 0)
{
TimestampTz current_time;
int millis_increment;
avl_dbase *dbary;
avl_dbase *db;
HASH_SEQ_STATUS seq;
int i;
/* put all the hash elements into an array */
dbary = palloc(nelems * sizeof(avl_dbase));
i = 0;
hash_seq_init(&seq, dbhash);
while ((db = hash_seq_search(&seq)) != NULL)
memcpy(&(dbary[i++]), db, sizeof(avl_dbase));
/* sort the array */
qsort(dbary, nelems, sizeof(avl_dbase), db_comparator);
/* this is the time interval between databases in the schedule */
millis_increment = 1000.0 * autovacuum_naptime / nelems;
current_time = GetCurrentTimestamp();
/*
* move the elements from the array into the dllist, setting the
* next_worker while walking the array
*/
for (i = 0; i < nelems; i++)
{
avl_dbase *db = &(dbary[i]);
Dlelem *elem;
current_time = TimestampTzPlusMilliseconds(current_time,
millis_increment);
db->adl_next_worker = current_time;
elem = DLNewElem(db);
/* later elements should go closer to the head of the list */
DLAddHead(DatabaseList, elem);
}
}
/* all done, clean up memory */
if (DatabaseListCxt != NULL)
MemoryContextDelete(DatabaseListCxt);
MemoryContextDelete(tmpcxt);
DatabaseListCxt = newcxt;
MemoryContextSwitchTo(oldcxt);
}
/* qsort comparator for avl_dbase, using adl_score */
static int
db_comparator(const void *a, const void *b)
{
if (((avl_dbase *) a)->adl_score == ((avl_dbase *) b)->adl_score)
return 0;
else
return (((avl_dbase *) a)->adl_score < ((avl_dbase *) b)->adl_score) ? 1 : -1;
}
/*
* do_start_worker
*
* Bare-bones procedure for starting an autovacuum worker from the launcher.
* It determines what database to work on, sets up shared memory stuff and
* signals postmaster to start the worker. It fails gracefully if invoked when
* autovacuum_workers are already active.
*
* Return value is the OID of the database that the worker is going to process,
* or InvalidOid if no worker was actually started.
*/
static Oid
do_start_worker(void)
{
List *dblist;
ListCell *cell;
TransactionId xidForceLimit;
bool for_xid_wrap;
avw_dbase *avdb;
TimestampTz current_time;
bool skipit = false;
Oid retval = InvalidOid;
MemoryContext tmpcxt,
oldcxt;
/* return quickly when there are no free workers */
LWLockAcquire(AutovacuumLock, LW_SHARED);
if (AutoVacuumShmem->av_freeWorkers == NULL)
{
LWLockRelease(AutovacuumLock);
return InvalidOid;
}
LWLockRelease(AutovacuumLock);
/*
* Create and switch to a temporary context to avoid leaking the memory
* allocated for the database list.
*/
tmpcxt = AllocSetContextCreate(CurrentMemoryContext,
"Start worker tmp cxt",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
oldcxt = MemoryContextSwitchTo(tmpcxt);
/* use fresh stats */
autovac_refresh_stats();
/* Get a list of databases */
dblist = get_database_list();
/*
* Determine the oldest datfrozenxid/relfrozenxid that we will allow to
* pass without forcing a vacuum. (This limit can be tightened for
* particular tables, but not loosened.)
*/
recentXid = ReadNewTransactionId();
xidForceLimit = recentXid - autovacuum_freeze_max_age;
/* ensure it's a "normal" XID, else TransactionIdPrecedes misbehaves */
if (xidForceLimit < FirstNormalTransactionId)
xidForceLimit -= FirstNormalTransactionId;
/*
* Choose a database to connect to. We pick the database that was least
* recently auto-vacuumed, or one that needs vacuuming to prevent Xid
* wraparound-related data loss. If any db at risk of wraparound is
* found, we pick the one with oldest datfrozenxid, independently of
* autovacuum times.
*
* Note that a database with no stats entry is not considered, except for
* Xid wraparound purposes. The theory is that if no one has ever
* connected to it since the stats were last initialized, it doesn't need
* vacuuming.
*
* XXX This could be improved if we had more info about whether it needs
* vacuuming before connecting to it. Perhaps look through the pgstats
* data for the database's tables? One idea is to keep track of the
* number of new and dead tuples per database in pgstats. However it
* isn't clear how to construct a metric that measures that and not cause
* starvation for less busy databases.
*/
avdb = NULL;
for_xid_wrap = false;
current_time = GetCurrentTimestamp();
foreach(cell, dblist)
{
avw_dbase *tmp = lfirst(cell);
Dlelem *elem;
/* Check to see if this one is at risk of wraparound */
if (TransactionIdPrecedes(tmp->adw_frozenxid, xidForceLimit))
{
if (avdb == NULL ||
TransactionIdPrecedes(tmp->adw_frozenxid, avdb->adw_frozenxid))
avdb = tmp;
for_xid_wrap = true;
continue;
}
else if (for_xid_wrap)
continue; /* ignore not-at-risk DBs */
/* Find pgstat entry if any */
tmp->adw_entry = pgstat_fetch_stat_dbentry(tmp->adw_datid);
/*
* Skip a database with no pgstat entry; it means it hasn't seen any
* activity.
*/
if (!tmp->adw_entry)
continue;
/*
* Also, skip a database that appears on the database list as having
* been processed recently (less than autovacuum_naptime seconds ago).
* We do this so that we don't select a database which we just
* selected, but that pgstat hasn't gotten around to updating the last
* autovacuum time yet.
*/
skipit = false;
elem = DatabaseList ? DLGetTail(DatabaseList) : NULL;
while (elem != NULL)
{
avl_dbase *dbp = DLE_VAL(elem);
if (dbp->adl_datid == tmp->adw_datid)
{
/*
* Skip this database if its next_worker value falls between
* the current time and the current time plus naptime.
*/
if (!TimestampDifferenceExceeds(dbp->adl_next_worker,
current_time, 0) &&
!TimestampDifferenceExceeds(current_time,
dbp->adl_next_worker,
autovacuum_naptime * 1000))
skipit = true;
break;
}
elem = DLGetPred(elem);
}
if (skipit)
continue;
/*
* Remember the db with oldest autovac time. (If we are here, both
* tmp->entry and db->entry must be non-null.)
*/
if (avdb == NULL ||
tmp->adw_entry->last_autovac_time < avdb->adw_entry->last_autovac_time)
avdb = tmp;
}
/* Found a database -- process it */
if (avdb != NULL)
{
WorkerInfo worker;
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
/*
* Get a worker entry from the freelist. We checked above, so there
* really should be a free slot -- complain very loudly if there
* isn't.
*/
worker = AutoVacuumShmem->av_freeWorkers;
if (worker == NULL)
elog(FATAL, "no free worker found");
AutoVacuumShmem->av_freeWorkers = (WorkerInfo) worker->wi_links.next;
worker->wi_dboid = avdb->adw_datid;
worker->wi_proc = NULL;
worker->wi_launchtime = GetCurrentTimestamp();
AutoVacuumShmem->av_startingWorker = worker;
LWLockRelease(AutovacuumLock);
SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER);
retval = avdb->adw_datid;
}
else if (skipit)
{
/*
* If we skipped all databases on the list, rebuild it, because it
* probably contains a dropped database.
*/
rebuild_database_list(InvalidOid);
}
MemoryContextSwitchTo(oldcxt);
MemoryContextDelete(tmpcxt);
return retval;
}
/*
* launch_worker
*
* Wrapper for starting a worker from the launcher. Besides actually starting
* it, update the database list to reflect the next time that another one will
* need to be started on the selected database. The actual database choice is
* left to do_start_worker.
*
* This routine is also expected to insert an entry into the database list if
* the selected database was previously absent from the list.
*/
static void
launch_worker(TimestampTz now)
{
Oid dbid;
Dlelem *elem;
dbid = do_start_worker();
if (OidIsValid(dbid))
{
/*
* Walk the database list and update the corresponding entry. If the
* database is not on the list, we'll recreate the list.
*/
elem = (DatabaseList == NULL) ? NULL : DLGetHead(DatabaseList);
while (elem != NULL)
{
avl_dbase *avdb = DLE_VAL(elem);
if (avdb->adl_datid == dbid)
{
/*
* add autovacuum_naptime seconds to the current time, and use
* that as the new "next_worker" field for this database.
*/
avdb->adl_next_worker =
TimestampTzPlusMilliseconds(now, autovacuum_naptime * 1000);
DLMoveToFront(elem);
break;
}
elem = DLGetSucc(elem);
}
/*
* If the database was not present in the database list, we rebuild
* the list. It's possible that the database does not get into the
* list anyway, for example if it's a database that doesn't have a
* pgstat entry, but this is not a problem because we don't want to
* schedule workers regularly into those in any case.
*/
if (elem == NULL)
rebuild_database_list(dbid);
}
}
/*
* Called from postmaster to signal a failure to fork a process to become
* worker. The postmaster should kill(SIGUSR1) the launcher shortly
* after calling this function.
*/
void
AutoVacWorkerFailed(void)
{
AutoVacuumShmem->av_signal[AutoVacForkFailed] = true;
}
/* SIGHUP: set flag to re-read config file at next convenient time */
static void
avl_sighup_handler(SIGNAL_ARGS)
{
got_SIGHUP = true;
}
/* SIGUSR1: a worker is up and running, or just finished */
static void
avl_sigusr1_handler(SIGNAL_ARGS)
{
got_SIGUSR1 = true;
}
/* SIGTERM: time to die */
static void
avl_sigterm_handler(SIGNAL_ARGS)
{
got_SIGTERM = true;
}
/*
* avl_quickdie occurs when signalled SIGQUIT from postmaster.
*
* Some backend has bought the farm, so we need to stop what we're doing
* and exit.
*/
static void
avl_quickdie(SIGNAL_ARGS)
{
PG_SETMASK(&BlockSig);
/*
* DO NOT proc_exit() -- we're here because shared memory may be
* corrupted, so we don't want to try to clean up our transaction. Just
* nail the windows shut and get out of town.
*
* Note we do exit(2) not exit(0). This is to force the postmaster into a
* system reset cycle if some idiot DBA sends a manual SIGQUIT to a random
* backend. This is necessary precisely because we don't clean up our
* shared memory state.
*/
exit(2);
}
/********************************************************************
* AUTOVACUUM WORKER CODE
********************************************************************/
#ifdef EXEC_BACKEND
/*
* forkexec routines for the autovacuum worker.
*
* Format up the arglist, then fork and exec.
*/
static pid_t
avworker_forkexec(void)
{
char *av[10];
int ac = 0;
av[ac++] = "postgres";
av[ac++] = "--forkavworker";
av[ac++] = NULL; /* filled in by postmaster_forkexec */
av[ac] = NULL;
Assert(ac < lengthof(av));
return postmaster_forkexec(ac, av);
}
/*
* We need this set from the outside, before InitProcess is called
*/
void
AutovacuumWorkerIAm(void)
{
am_autovacuum_worker = true;
}
#endif
/*
* Main entry point for autovacuum worker process.
*
* This code is heavily based on pgarch.c, q.v.
*/
int
StartAutoVacWorker(void)
{
pid_t worker_pid;
#ifdef EXEC_BACKEND
switch ((worker_pid = avworker_forkexec()))
#else
switch ((worker_pid = fork_process()))
#endif
{
case -1:
ereport(LOG,
(errmsg("could not fork autovacuum worker process: %m")));
return 0;
#ifndef EXEC_BACKEND
case 0:
/* in postmaster child ... */
/* Close the postmaster's sockets */
ClosePostmasterPorts(false);
/* Lose the postmaster's on-exit routines */
on_exit_reset();
AutoVacWorkerMain(0, NULL);
break;
#endif
default:
return (int) worker_pid;
}
/* shouldn't get here */
return 0;
}
/*
* AutoVacWorkerMain
*/
NON_EXEC_STATIC void
AutoVacWorkerMain(int argc, char *argv[])
{
sigjmp_buf local_sigjmp_buf;
Oid dbid;
/* we are a postmaster subprocess now */
IsUnderPostmaster = true;
am_autovacuum_worker = true;
/* reset MyProcPid */
MyProcPid = getpid();
/* record Start Time for logging */
MyStartTime = time(NULL);
/* Identify myself via ps */
init_ps_display("autovacuum worker process", "", "", "");
SetProcessingMode(InitProcessing);
/*
* If possible, make this process a group leader, so that the postmaster
* can signal any child processes too. (autovacuum probably never has any
* child processes, but for consistency we make all postmaster child
* processes do this.)
*/
#ifdef HAVE_SETSID
if (setsid() < 0)
elog(FATAL, "setsid() failed: %m");
#endif
/*
* Set up signal handlers. We operate on databases much like a regular
* backend, so we use the same signal handling. See equivalent code in
* tcop/postgres.c.
*
* Currently, we don't pay attention to postgresql.conf changes that
* happen during a single daemon iteration, so we can ignore SIGHUP.
*/
pqsignal(SIGHUP, SIG_IGN);
/*
* SIGINT is used to signal cancelling the current table's vacuum; SIGTERM
* means abort and exit cleanly, and SIGQUIT means abandon ship.
*/
pqsignal(SIGINT, StatementCancelHandler);
pqsignal(SIGTERM, die);
pqsignal(SIGQUIT, quickdie);
pqsignal(SIGALRM, handle_sig_alarm);
pqsignal(SIGPIPE, SIG_IGN);
pqsignal(SIGUSR1, CatchupInterruptHandler);
/* We don't listen for async notifies */
pqsignal(SIGUSR2, SIG_IGN);
pqsignal(SIGFPE, FloatExceptionHandler);
pqsignal(SIGCHLD, SIG_DFL);
/* Early initialization */
BaseInit();
/*
* Create a per-backend PGPROC struct in shared memory, except in the
* EXEC_BACKEND case where this was done in SubPostmasterMain. We must do
* this before we can use LWLocks (and in the EXEC_BACKEND case we already
* had to do some stuff with LWLocks).
*/
#ifndef EXEC_BACKEND
InitProcess();
#endif
/*
* If an exception is encountered, processing resumes here.
*
* See notes in postgres.c about the design of this coding.
*/
if (sigsetjmp(local_sigjmp_buf, 1) != 0)
{
/* Prevents interrupts while cleaning up */
HOLD_INTERRUPTS();
/* Report the error to the server log */
EmitErrorReport();
/*
* We can now go away. Note that because we called InitProcess, a
* callback was registered to do ProcKill, which will clean up
* necessary state.
*/
proc_exit(0);
}
/* We can now handle ereport(ERROR) */
PG_exception_stack = &local_sigjmp_buf;
PG_SETMASK(&UnBlockSig);
/*
* Force zero_damaged_pages OFF in the autovac process, even if it is set
* in postgresql.conf. We don't really want such a dangerous option being
* applied non-interactively.
*/
SetConfigOption("zero_damaged_pages", "false", PGC_SUSET, PGC_S_OVERRIDE);
/*
* Force statement_timeout to zero to avoid a timeout setting from
* preventing regular maintenance from being executed.
*/
SetConfigOption("statement_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
/*
* Get the info about the database we're going to work on.
*/
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
/*
* beware of startingWorker being INVALID; this should normally not
* happen, but if a worker fails after forking and before this, the
* launcher might have decided to remove it from the queue and start
* again.
*/
if (AutoVacuumShmem->av_startingWorker != NULL)
{
MyWorkerInfo = AutoVacuumShmem->av_startingWorker;
dbid = MyWorkerInfo->wi_dboid;
MyWorkerInfo->wi_proc = MyProc;
/* insert into the running list */
SHMQueueInsertBefore(&AutoVacuumShmem->av_runningWorkers,
&MyWorkerInfo->wi_links);
/*
* remove from the "starting" pointer, so that the launcher can start
* a new worker if required
*/
AutoVacuumShmem->av_startingWorker = NULL;
LWLockRelease(AutovacuumLock);
on_shmem_exit(FreeWorkerInfo, 0);
/* wake up the launcher */
if (AutoVacuumShmem->av_launcherpid != 0)
kill(AutoVacuumShmem->av_launcherpid, SIGUSR1);
}
else
{
/* no worker entry for me, go away */
elog(WARNING, "autovacuum worker started without a worker entry");
dbid = InvalidOid;
LWLockRelease(AutovacuumLock);
}
if (OidIsValid(dbid))
{
char *dbname;
/*
* Report autovac startup to the stats collector. We deliberately do
* this before InitPostgres, so that the last_autovac_time will get
* updated even if the connection attempt fails. This is to prevent
* autovac from getting "stuck" repeatedly selecting an unopenable
* database, rather than making any progress on stuff it can connect
* to.
*/
pgstat_report_autovac(dbid);
/*
* Connect to the selected database
*
* Note: if we have selected a just-deleted database (due to using
* stale stats info), we'll fail and exit here.
*/
InitPostgres(NULL, dbid, NULL, &dbname);
SetProcessingMode(NormalProcessing);
set_ps_display(dbname, false);
ereport(DEBUG1,
(errmsg("autovacuum: processing database \"%s\"", dbname)));
if (PostAuthDelay)
pg_usleep(PostAuthDelay * 1000000L);
/* And do an appropriate amount of work */
recentXid = ReadNewTransactionId();
do_autovacuum();
}
/*
* The launcher will be notified of my death in ProcKill, *if* we managed
* to get a worker slot at all
*/
/* All done, go away */
proc_exit(0);
}
/*
* Return a WorkerInfo to the free list
*/
static void
FreeWorkerInfo(int code, Datum arg)
{
if (MyWorkerInfo != NULL)
{
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
/*
* Wake the launcher up so that he can launch a new worker immediately
* if required. We only save the launcher's PID in local memory here;
* the actual signal will be sent when the PGPROC is recycled. Note
* that we always do this, so that the launcher can rebalance the cost
* limit setting of the remaining workers.
*
* We somewhat ignore the risk that the launcher changes its PID
* between we reading it and the actual kill; we expect ProcKill to be
* called shortly after us, and we assume that PIDs are not reused too
* quickly after a process exits.
*/
AutovacuumLauncherPid = AutoVacuumShmem->av_launcherpid;
SHMQueueDelete(&MyWorkerInfo->wi_links);
MyWorkerInfo->wi_links.next = (SHM_QUEUE *) AutoVacuumShmem->av_freeWorkers;
MyWorkerInfo->wi_dboid = InvalidOid;
MyWorkerInfo->wi_tableoid = InvalidOid;
MyWorkerInfo->wi_proc = NULL;
MyWorkerInfo->wi_launchtime = 0;
MyWorkerInfo->wi_cost_delay = 0;
MyWorkerInfo->wi_cost_limit = 0;
MyWorkerInfo->wi_cost_limit_base = 0;
AutoVacuumShmem->av_freeWorkers = MyWorkerInfo;
/* not mine anymore */
MyWorkerInfo = NULL;
/*
* now that we're inactive, cause a rebalancing of the surviving
* workers
*/
AutoVacuumShmem->av_signal[AutoVacRebalance] = true;
LWLockRelease(AutovacuumLock);
}
}
/*
* Update the cost-based delay parameters, so that multiple workers consume
* each a fraction of the total available I/O.
*/
void
AutoVacuumUpdateDelay(void)
{
if (MyWorkerInfo)
{
VacuumCostDelay = MyWorkerInfo->wi_cost_delay;
VacuumCostLimit = MyWorkerInfo->wi_cost_limit;
}
}
/*
* autovac_balance_cost
* Recalculate the cost limit setting for each active workers.
*
* Caller must hold the AutovacuumLock in exclusive mode.
*/
static void
autovac_balance_cost(void)
{
WorkerInfo worker;
/*
* note: in cost_limit, zero also means use value from elsewhere, because
* zero is not a valid value.
*/
int vac_cost_limit = (autovacuum_vac_cost_limit > 0 ?
autovacuum_vac_cost_limit : VacuumCostLimit);
int vac_cost_delay = (autovacuum_vac_cost_delay >= 0 ?
autovacuum_vac_cost_delay : VacuumCostDelay);
double cost_total;
double cost_avail;
/* not set? nothing to do */
if (vac_cost_limit <= 0 || vac_cost_delay <= 0)
return;
/* caculate the total base cost limit of active workers */
cost_total = 0.0;
worker = (WorkerInfo) SHMQueueNext(&AutoVacuumShmem->av_runningWorkers,
&AutoVacuumShmem->av_runningWorkers,
offsetof(WorkerInfoData, wi_links));
while (worker)
{
if (worker->wi_proc != NULL &&
worker->wi_cost_limit_base > 0 && worker->wi_cost_delay > 0)
cost_total +=
(double) worker->wi_cost_limit_base / worker->wi_cost_delay;
worker = (WorkerInfo) SHMQueueNext(&AutoVacuumShmem->av_runningWorkers,
&worker->wi_links,
offsetof(WorkerInfoData, wi_links));
}
/* there are no cost limits -- nothing to do */
if (cost_total <= 0)
return;
/*
* Adjust each cost limit of active workers to balance the total of cost
* limit to autovacuum_vacuum_cost_limit.
*/
cost_avail = (double) vac_cost_limit / vac_cost_delay;
worker = (WorkerInfo) SHMQueueNext(&AutoVacuumShmem->av_runningWorkers,
&AutoVacuumShmem->av_runningWorkers,
offsetof(WorkerInfoData, wi_links));
while (worker)
{
if (worker->wi_proc != NULL &&
worker->wi_cost_limit_base > 0 && worker->wi_cost_delay > 0)
{
int limit = (int)
(cost_avail * worker->wi_cost_limit_base / cost_total);
/*
* We put a lower bound of 1 to the cost_limit, to avoid division-
* by-zero in the vacuum code.
*/
worker->wi_cost_limit = Max(Min(limit, worker->wi_cost_limit_base), 1);
elog(DEBUG2, "autovac_balance_cost(pid=%u db=%u, rel=%u, cost_limit=%d, cost_delay=%d)",
worker->wi_proc->pid, worker->wi_dboid,
worker->wi_tableoid, worker->wi_cost_limit, worker->wi_cost_delay);
}
worker = (WorkerInfo) SHMQueueNext(&AutoVacuumShmem->av_runningWorkers,
&worker->wi_links,
offsetof(WorkerInfoData, wi_links));
}
}
/*
* get_database_list
*
* Return a list of all databases. Note we cannot use pg_database,
* because we aren't connected; we use the flat database file.
*/
static List *
get_database_list(void)
{
char *filename;
List *dblist = NIL;
char thisname[NAMEDATALEN];
FILE *db_file;
Oid db_id;
Oid db_tablespace;
TransactionId db_frozenxid;
filename = database_getflatfilename();
db_file = AllocateFile(filename, "r");
if (db_file == NULL)
ereport(FATAL,
(errcode_for_file_access(),
errmsg("could not open file \"%s\": %m", filename)));
while (read_pg_database_line(db_file, thisname, &db_id,
&db_tablespace, &db_frozenxid))
{
avw_dbase *avdb;
avdb = (avw_dbase *) palloc(sizeof(avw_dbase));
avdb->adw_datid = db_id;
avdb->adw_name = pstrdup(thisname);
avdb->adw_frozenxid = db_frozenxid;
/* this gets set later: */
avdb->adw_entry = NULL;
dblist = lappend(dblist, avdb);
}
FreeFile(db_file);
pfree(filename);
return dblist;
}
/*
* Process a database table-by-table
*
* Note that CHECK_FOR_INTERRUPTS is supposed to be used in certain spots in
* order not to ignore shutdown commands for too long.
*/
static void
do_autovacuum(void)
{
Relation classRel,
avRel;
HeapTuple tuple;
HeapScanDesc relScan;
Form_pg_database dbForm;
List *table_oids = NIL;
HASHCTL ctl;
HTAB *table_toast_map;
ListCell *volatile cell;
PgStat_StatDBEntry *shared;
PgStat_StatDBEntry *dbentry;
BufferAccessStrategy bstrategy;
ScanKeyData key;
/*
* StartTransactionCommand and CommitTransactionCommand will automatically
* switch to other contexts. We need this one to keep the list of
* relations to vacuum/analyze across transactions.
*/
AutovacMemCxt = AllocSetContextCreate(TopMemoryContext,
"AV worker",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
MemoryContextSwitchTo(AutovacMemCxt);
/*
* may be NULL if we couldn't find an entry (only happens if we are
* forcing a vacuum for anti-wrap purposes).
*/
dbentry = pgstat_fetch_stat_dbentry(MyDatabaseId);
/* Start a transaction so our commands have one to play into. */
StartTransactionCommand();
/*
* Clean up any dead statistics collector entries for this DB. We always
* want to do this exactly once per DB-processing cycle, even if we find
* nothing worth vacuuming in the database.
*/
pgstat_vacuum_stat();
/*
* Find the pg_database entry and select the default freeze_min_age. We
* use zero in template and nonconnectable databases, else the system-wide
* default.
*/
tuple = SearchSysCache(DATABASEOID,
ObjectIdGetDatum(MyDatabaseId),
0, 0, 0);
if (!HeapTupleIsValid(tuple))
elog(ERROR, "cache lookup failed for database %u", MyDatabaseId);
dbForm = (Form_pg_database) GETSTRUCT(tuple);
if (dbForm->datistemplate || !dbForm->datallowconn)
default_freeze_min_age = 0;
else
default_freeze_min_age = vacuum_freeze_min_age;
ReleaseSysCache(tuple);
/* StartTransactionCommand changed elsewhere */
MemoryContextSwitchTo(AutovacMemCxt);
/* The database hash where pgstat keeps shared relations */
shared = pgstat_fetch_stat_dbentry(InvalidOid);
classRel = heap_open(RelationRelationId, AccessShareLock);
avRel = heap_open(AutovacuumRelationId, AccessShareLock);
/* create hash table for toast <-> main relid mapping */
MemSet(&ctl, 0, sizeof(ctl));
ctl.keysize = sizeof(Oid);
ctl.entrysize = sizeof(Oid) * 2;
ctl.hash = oid_hash;
table_toast_map = hash_create("TOAST to main relid map",
100,
&ctl,
HASH_ELEM | HASH_FUNCTION);
/*
* Scan pg_class to determine which tables to vacuum.
*
* We do this in two passes: on the first one we collect the list of
* plain relations, and on the second one we collect TOAST tables.
* The reason for doing the second pass is that during it we want to use
* the main relation's pg_autovacuum entry if the TOAST table does not have
* any, and we cannot obtain it unless we know beforehand what's the main
* table OID.
*
* We need to check TOAST tables separately because in cases with short,
* wide tables there might be proportionally much more activity in the
* TOAST table than in its parent.
*/
ScanKeyInit(&key,
Anum_pg_class_relkind,
BTEqualStrategyNumber, F_CHAREQ,
CharGetDatum(RELKIND_RELATION));
relScan = heap_beginscan(classRel, SnapshotNow, 1, &key);
/*
* On the first pass, we collect main tables to vacuum, and also the
* main table relid to TOAST relid mapping.
*/
while ((tuple = heap_getnext(relScan, ForwardScanDirection)) != NULL)
{
Form_pg_class classForm = (Form_pg_class) GETSTRUCT(tuple);
Form_pg_autovacuum avForm = NULL;
PgStat_StatTabEntry *tabentry;
HeapTuple avTup;
Oid relid;
bool dovacuum;
bool doanalyze;
bool wraparound;
int backendID;
relid = HeapTupleGetOid(tuple);
/* Fetch the pg_autovacuum tuple for the relation, if any */
avTup = get_pg_autovacuum_tuple_relid(avRel, relid, NULL);
if (HeapTupleIsValid(avTup))
avForm = (Form_pg_autovacuum) GETSTRUCT(avTup);
/* Fetch the pgstat entry for this table */
tabentry = get_pgstat_tabentry_relid(relid, classForm->relisshared,
shared, dbentry);
/* Check if it needs vacuum or analyze */
relation_needs_vacanalyze(relid, avForm, classForm, tabentry,
&dovacuum, &doanalyze, &wraparound);
/*
* Check if it is a temp table (presumably, of some other backend's).
* We cannot safely process other backends' temp tables.
*/
backendID = GetTempNamespaceBackendId(classForm->relnamespace);
if (backendID > 0)
{
/* We just ignore it if the owning backend is still active */
if (backendID == MyBackendId || !BackendIdIsActive(backendID))
{
/*
* We found an orphan temp table (which was probably left
* behind by a crashed backend). If it's so old as to need
* vacuum for wraparound, forcibly drop it. Otherwise just
* log a complaint.
*/
if (wraparound)
{
ObjectAddress object;
ereport(LOG,
(errmsg("autovacuum: dropping orphan temp table \"%s\".\"%s\" in database \"%s\"",
get_namespace_name(classForm->relnamespace),
NameStr(classForm->relname),
get_database_name(MyDatabaseId))));
object.classId = RelationRelationId;
object.objectId = relid;
object.objectSubId = 0;
performDeletion(&object, DROP_CASCADE);
}
else
{
ereport(LOG,
(errmsg("autovacuum: found orphan temp table \"%s\".\"%s\" in database \"%s\"",
get_namespace_name(classForm->relnamespace),
NameStr(classForm->relname),
get_database_name(MyDatabaseId))));
}
}
}
else
{
/* Plain relations that need work are added to table_oids */
if (dovacuum || doanalyze)
table_oids = lappend_oid(table_oids, relid);
/*
* Remember the association for the second pass. Note: we must do
* this even if the table is going to be vacuumed, because we
* don't automatically vacuum toast tables along the parent table.
*/
if (OidIsValid(classForm->reltoastrelid))
{
av_relation *hentry;
bool found;
hentry = hash_search(table_toast_map,
&classForm->reltoastrelid,
HASH_ENTER, &found);
if (!found)
{
/* hash_search already filled in the key */
hentry->ar_relid = relid;
}
}
}
if (HeapTupleIsValid(avTup))
heap_freetuple(avTup);
}
heap_endscan(relScan);
/* second pass: check TOAST tables */
ScanKeyInit(&key,
Anum_pg_class_relkind,
BTEqualStrategyNumber, F_CHAREQ,
CharGetDatum(RELKIND_TOASTVALUE));
relScan = heap_beginscan(classRel, SnapshotNow, 1, &key);
while ((tuple = heap_getnext(relScan, ForwardScanDirection)) != NULL)
{
Form_pg_class classForm = (Form_pg_class) GETSTRUCT(tuple);
Form_pg_autovacuum avForm = NULL;
PgStat_StatTabEntry *tabentry;
HeapTuple avTup;
Oid relid;
bool dovacuum;
bool doanalyze;
bool wraparound;
/*
* Skip temp tables (i.e. those in temp namespaces). We cannot safely
* process other backends' temp tables.
*/
if (isAnyTempNamespace(classForm->relnamespace))
continue;
relid = HeapTupleGetOid(tuple);
/* Fetch the pg_autovacuum tuple for this rel */
avTup = get_pg_autovacuum_tuple_relid(avRel, relid, table_toast_map);
if (HeapTupleIsValid(avTup))
avForm = (Form_pg_autovacuum) GETSTRUCT(avTup);
/* Fetch the pgstat entry for this table */
tabentry = get_pgstat_tabentry_relid(relid, classForm->relisshared,
shared, dbentry);
relation_needs_vacanalyze(relid, avForm, classForm, tabentry,
&dovacuum, &doanalyze, &wraparound);
/* ignore analyze for toast tables */
if (dovacuum)
table_oids = lappend_oid(table_oids, relid);
}
heap_endscan(relScan);
heap_close(avRel, AccessShareLock);
heap_close(classRel, AccessShareLock);
/*
* Create a buffer access strategy object for VACUUM to use. We want to
* use the same one across all the vacuum operations we perform, since the
* point is for VACUUM not to blow out the shared cache.
*/
bstrategy = GetAccessStrategy(BAS_VACUUM);
/*
* create a memory context to act as fake PortalContext, so that the
* contexts created in the vacuum code are cleaned up for each table.
*/
PortalContext = AllocSetContextCreate(AutovacMemCxt,
"Autovacuum Portal",
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
/*
* Perform operations on collected tables.
*/
foreach(cell, table_oids)
{
Oid relid = lfirst_oid(cell);
autovac_table *tab;
WorkerInfo worker;
bool skipit;
CHECK_FOR_INTERRUPTS();
/*
* hold schedule lock from here until we're sure that this table still
* needs vacuuming. We also need the AutovacuumLock to walk the
* worker array, but we'll let go of that one quickly.
*/
LWLockAcquire(AutovacuumScheduleLock, LW_EXCLUSIVE);
LWLockAcquire(AutovacuumLock, LW_SHARED);
/*
* Check whether the table is being vacuumed concurrently by another
* worker.
*/
skipit = false;
worker = (WorkerInfo) SHMQueueNext(&AutoVacuumShmem->av_runningWorkers,
&AutoVacuumShmem->av_runningWorkers,
offsetof(WorkerInfoData, wi_links));
while (worker)
{
/* ignore myself */
if (worker == MyWorkerInfo)
goto next_worker;
/* ignore workers in other databases */
if (worker->wi_dboid != MyDatabaseId)
goto next_worker;
if (worker->wi_tableoid == relid)
{
skipit = true;
break;
}
next_worker:
worker = (WorkerInfo) SHMQueueNext(&AutoVacuumShmem->av_runningWorkers,
&worker->wi_links,
offsetof(WorkerInfoData, wi_links));
}
LWLockRelease(AutovacuumLock);
if (skipit)
{
LWLockRelease(AutovacuumScheduleLock);
continue;
}
/*
* Check whether pgstat data still says we need to vacuum this table.
* It could have changed if something else processed the table while
* we weren't looking.
*
* Note: we have a special case in pgstat code to ensure that the stats
* we read are as up-to-date as possible, to avoid the problem that
* somebody just finished vacuuming this table. The window to the race
* condition is not closed but it is very small.
*/
MemoryContextSwitchTo(AutovacMemCxt);
tab = table_recheck_autovac(relid, table_toast_map);
if (tab == NULL)
{
/* someone else vacuumed the table */
LWLockRelease(AutovacuumScheduleLock);
continue;
}
/*
* Ok, good to go. Store the table in shared memory before releasing
* the lock so that other workers don't vacuum it concurrently.
*/
MyWorkerInfo->wi_tableoid = relid;
LWLockRelease(AutovacuumScheduleLock);
/* Set the initial vacuum cost parameters for this table */
VacuumCostDelay = tab->at_vacuum_cost_delay;
VacuumCostLimit = tab->at_vacuum_cost_limit;
/* Last fixups before actually starting to work */
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
/* advertise my cost delay parameters for the balancing algorithm */
MyWorkerInfo->wi_cost_delay = tab->at_vacuum_cost_delay;
MyWorkerInfo->wi_cost_limit = tab->at_vacuum_cost_limit;
MyWorkerInfo->wi_cost_limit_base = tab->at_vacuum_cost_limit;
/* do a balance */
autovac_balance_cost();
/* done */
LWLockRelease(AutovacuumLock);
/* clean up memory before each iteration */
MemoryContextResetAndDeleteChildren(PortalContext);
/*
* Save the relation name for a possible error message, to avoid a
* catalog lookup in case of an error. If any of these return NULL,
* then the relation has been dropped since last we checked; skip it.
* Note: they must live in a long-lived memory context because we call
* vacuum and analyze in different transactions.
*/
tab->at_relname = get_rel_name(tab->at_relid);
tab->at_nspname = get_namespace_name(get_rel_namespace(tab->at_relid));
tab->at_datname = get_database_name(MyDatabaseId);
if (!tab->at_relname || !tab->at_nspname || !tab->at_datname)
goto deleted;
/*
* We will abort vacuuming the current table if something errors out,
* and continue with the next one in schedule; in particular, this
* happens if we are interrupted with SIGINT.
*/
PG_TRY();
{
/* have at it */
MemoryContextSwitchTo(TopTransactionContext);
autovacuum_do_vac_analyze(tab, bstrategy);
/*
* Clear a possible query-cancel signal, to avoid a late reaction
* to an automatically-sent signal because of vacuuming the
* current table (we're done with it, so it would make no sense to
* cancel at this point.)
*/
QueryCancelPending = false;
}
PG_CATCH();
{
/*
* Abort the transaction, start a new one, and proceed with the
* next table in our list.
*/
HOLD_INTERRUPTS();
if (tab->at_dovacuum)
errcontext("automatic vacuum of table \"%s.%s.%s\"",
tab->at_datname, tab->at_nspname, tab->at_relname);
else
errcontext("automatic analyze of table \"%s.%s.%s\"",
tab->at_datname, tab->at_nspname, tab->at_relname);
EmitErrorReport();
/* this resets the PGPROC flags too */
AbortOutOfAnyTransaction();
FlushErrorState();
MemoryContextResetAndDeleteChildren(PortalContext);
/* restart our transaction for the following operations */
StartTransactionCommand();
RESUME_INTERRUPTS();
}
PG_END_TRY();
/* the PGPROC flags are reset at the next end of transaction */
/* be tidy */
deleted:
if (tab->at_datname != NULL)
pfree(tab->at_datname);
if (tab->at_nspname != NULL)
pfree(tab->at_nspname);
if (tab->at_relname != NULL)
pfree(tab->at_relname);
pfree(tab);
/* remove my info from shared memory */
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
MyWorkerInfo->wi_tableoid = InvalidOid;
LWLockRelease(AutovacuumLock);
}
/*
* We leak table_toast_map here (among other things), but since we're going
* away soon, it's not a problem.
*/
/*
* Update pg_database.datfrozenxid, and truncate pg_clog if possible. We
* only need to do this once, not after each table.
*/
vac_update_datfrozenxid();
/* Finally close out the last transaction. */
CommitTransactionCommand();
}
/*
* Returns a copy of the pg_autovacuum tuple for the given relid, or NULL if
* there isn't any. avRel is pg_autovacuum, already open and suitably locked.
*
* If table_toast_map is not null, use it to find an alternative OID with which
* to search a pg_autovacuum entry, if the passed relid does not yield one
* directly.
*/
static HeapTuple
get_pg_autovacuum_tuple_relid(Relation avRel, Oid relid,
HTAB *table_toast_map)
{
ScanKeyData entry[1];
SysScanDesc avScan;
HeapTuple avTup;
ScanKeyInit(&entry[0],
Anum_pg_autovacuum_vacrelid,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(relid));
avScan = systable_beginscan(avRel, AutovacuumRelidIndexId, true,
SnapshotNow, 1, entry);
avTup = systable_getnext(avScan);
if (HeapTupleIsValid(avTup))
avTup = heap_copytuple(avTup);
systable_endscan(avScan);
if (!HeapTupleIsValid(avTup) && table_toast_map != NULL)
{
av_relation *hentry;
bool found;
hentry = hash_search(table_toast_map, &relid, HASH_FIND, &found);
if (found)
/* avoid second recursion */
avTup = get_pg_autovacuum_tuple_relid(avRel, hentry->ar_relid,
NULL);
}
return avTup;
}
/*
* get_pgstat_tabentry_relid
*
* Fetch the pgstat entry of a table, either local to a database or shared.
*/
static PgStat_StatTabEntry *
get_pgstat_tabentry_relid(Oid relid, bool isshared, PgStat_StatDBEntry *shared,
PgStat_StatDBEntry *dbentry)
{
PgStat_StatTabEntry *tabentry = NULL;
if (isshared)
{
if (PointerIsValid(shared))
tabentry = hash_search(shared->tables, &relid,
HASH_FIND, NULL);
}
else if (PointerIsValid(dbentry))
tabentry = hash_search(dbentry->tables, &relid,
HASH_FIND, NULL);
return tabentry;
}
/*
* table_recheck_autovac
*
* Recheck whether a table still needs vacuum or analyze. Return value is a
* valid autovac_table pointer if it does, NULL otherwise.
*
* Note that the returned autovac_table does not have the name fields set.
*/
static autovac_table *
table_recheck_autovac(Oid relid, HTAB *table_toast_map)
{
Form_pg_autovacuum avForm = NULL;
Form_pg_class classForm;
HeapTuple classTup;
HeapTuple avTup;
Relation avRel;
bool dovacuum;
bool doanalyze;
autovac_table *tab = NULL;
PgStat_StatTabEntry *tabentry;
PgStat_StatDBEntry *shared;
PgStat_StatDBEntry *dbentry;
bool wraparound;
/* use fresh stats */
autovac_refresh_stats();
shared = pgstat_fetch_stat_dbentry(InvalidOid);
dbentry = pgstat_fetch_stat_dbentry(MyDatabaseId);
/* fetch the relation's relcache entry */
classTup = SearchSysCacheCopy(RELOID,
ObjectIdGetDatum(relid),
0, 0, 0);
if (!HeapTupleIsValid(classTup))
return NULL;
classForm = (Form_pg_class) GETSTRUCT(classTup);
/*
* Fetch the pg_autovacuum entry, if any. For a toast table, also try the
* main rel's pg_autovacuum entry if there isn't one for the TOAST table
* itself.
*/
avRel = heap_open(AutovacuumRelationId, AccessShareLock);
avTup = get_pg_autovacuum_tuple_relid(avRel, relid,
classForm->relkind == RELKIND_TOASTVALUE ? table_toast_map : NULL);
if (HeapTupleIsValid(avTup))
avForm = (Form_pg_autovacuum) GETSTRUCT(avTup);
/* fetch the pgstat table entry */
tabentry = get_pgstat_tabentry_relid(relid, classForm->relisshared,
shared, dbentry);
relation_needs_vacanalyze(relid, avForm, classForm, tabentry,
&dovacuum, &doanalyze, &wraparound);
/* ignore ANALYZE for toast tables */
if (classForm->relkind == RELKIND_TOASTVALUE)
doanalyze = false;
/* OK, it needs something done */
if (doanalyze || dovacuum)
{
int freeze_min_age;
int vac_cost_limit;
int vac_cost_delay;
/*
* Calculate the vacuum cost parameters and the minimum freeze age. If
* there is a tuple in pg_autovacuum, use it; else, use the GUC
* defaults. Note that the fields may contain "-1" (or indeed any
* negative value), which means use the GUC defaults for each setting.
* In cost_limit, the value 0 also means to use the value from
* elsewhere.
*/
if (avForm != NULL)
{
vac_cost_limit = (avForm->vac_cost_limit > 0) ?
avForm->vac_cost_limit :
((autovacuum_vac_cost_limit > 0) ?
autovacuum_vac_cost_limit : VacuumCostLimit);
vac_cost_delay = (avForm->vac_cost_delay >= 0) ?
avForm->vac_cost_delay :
((autovacuum_vac_cost_delay >= 0) ?
autovacuum_vac_cost_delay : VacuumCostDelay);
freeze_min_age = (avForm->freeze_min_age >= 0) ?
avForm->freeze_min_age : default_freeze_min_age;
}
else
{
vac_cost_limit = (autovacuum_vac_cost_limit > 0) ?
autovacuum_vac_cost_limit : VacuumCostLimit;
vac_cost_delay = (autovacuum_vac_cost_delay >= 0) ?
autovacuum_vac_cost_delay : VacuumCostDelay;
freeze_min_age = default_freeze_min_age;
}
tab = palloc(sizeof(autovac_table));
tab->at_relid = relid;
tab->at_dovacuum = dovacuum;
tab->at_doanalyze = doanalyze;
tab->at_freeze_min_age = freeze_min_age;
tab->at_vacuum_cost_limit = vac_cost_limit;
tab->at_vacuum_cost_delay = vac_cost_delay;
tab->at_wraparound = wraparound;
tab->at_relname = NULL;
tab->at_nspname = NULL;
tab->at_datname = NULL;
}
heap_close(avRel, AccessShareLock);
if (HeapTupleIsValid(avTup))
heap_freetuple(avTup);
heap_freetuple(classTup);
return tab;
}
/*
* relation_needs_vacanalyze
*
* Check whether a relation needs to be vacuumed or analyzed; return each into
* "dovacuum" and "doanalyze", respectively. Also return whether the vacuum is
* being forced because of Xid wraparound. avForm and tabentry can be NULL,
* classForm shouldn't.
*
* A table needs to be vacuumed if the number of dead tuples exceeds a
* threshold. This threshold is calculated as
*
* threshold = vac_base_thresh + vac_scale_factor * reltuples
*
* For analyze, the analysis done is that the number of tuples inserted,
* deleted and updated since the last analyze exceeds a threshold calculated
* in the same fashion as above. Note that the collector actually stores
* the number of tuples (both live and dead) that there were as of the last
* analyze. This is asymmetric to the VACUUM case.
*
* We also force vacuum if the table's relfrozenxid is more than freeze_max_age
* transactions back.
*
* A table whose pg_autovacuum.enabled value is false, is automatically
* skipped (unless we have to vacuum it due to freeze_max_age). Thus
* autovacuum can be disabled for specific tables. Also, when the stats
* collector does not have data about a table, it will be skipped.
*
* A table whose vac_base_thresh value is <0 takes the base value from the
* autovacuum_vacuum_threshold GUC variable. Similarly, a vac_scale_factor
* value <0 is substituted with the value of
* autovacuum_vacuum_scale_factor GUC variable. Ditto for analyze.
*/
static void
relation_needs_vacanalyze(Oid relid,
Form_pg_autovacuum avForm,
Form_pg_class classForm,
PgStat_StatTabEntry *tabentry,
/* output params below */
bool *dovacuum,
bool *doanalyze,
bool *wraparound)
{
bool force_vacuum;
float4 reltuples; /* pg_class.reltuples */
/* constants from pg_autovacuum or GUC variables */
int vac_base_thresh,
anl_base_thresh;
float4 vac_scale_factor,
anl_scale_factor;
/* thresholds calculated from above constants */
float4 vacthresh,
anlthresh;
/* number of vacuum (resp. analyze) tuples at this time */
float4 vactuples,
anltuples;
/* freeze parameters */
int freeze_max_age;
TransactionId xidForceLimit;
AssertArg(classForm != NULL);
AssertArg(OidIsValid(relid));
/*
* Determine vacuum/analyze equation parameters. If there is a tuple in
* pg_autovacuum, use it; else, use the GUC defaults. Note that the
* fields may contain "-1" (or indeed any negative value), which means use
* the GUC defaults for each setting.
*/
if (avForm != NULL)
{
vac_scale_factor = (avForm->vac_scale_factor >= 0) ?
avForm->vac_scale_factor : autovacuum_vac_scale;
vac_base_thresh = (avForm->vac_base_thresh >= 0) ?
avForm->vac_base_thresh : autovacuum_vac_thresh;
anl_scale_factor = (avForm->anl_scale_factor >= 0) ?
avForm->anl_scale_factor : autovacuum_anl_scale;
anl_base_thresh = (avForm->anl_base_thresh >= 0) ?
avForm->anl_base_thresh : autovacuum_anl_thresh;
freeze_max_age = (avForm->freeze_max_age >= 0) ?
Min(avForm->freeze_max_age, autovacuum_freeze_max_age) :
autovacuum_freeze_max_age;
}
else
{
vac_scale_factor = autovacuum_vac_scale;
vac_base_thresh = autovacuum_vac_thresh;
anl_scale_factor = autovacuum_anl_scale;
anl_base_thresh = autovacuum_anl_thresh;
freeze_max_age = autovacuum_freeze_max_age;
}
/* Force vacuum if table is at risk of wraparound */
xidForceLimit = recentXid - freeze_max_age;
if (xidForceLimit < FirstNormalTransactionId)
xidForceLimit -= FirstNormalTransactionId;
force_vacuum = (TransactionIdIsNormal(classForm->relfrozenxid) &&
TransactionIdPrecedes(classForm->relfrozenxid,
xidForceLimit));
*wraparound = force_vacuum;
/* User disabled it in pg_autovacuum? (But ignore if at risk) */
if (avForm && !avForm->enabled && !force_vacuum)
{
*doanalyze = false;
*dovacuum = false;
return;
}
if (PointerIsValid(tabentry))
{
reltuples = classForm->reltuples;
vactuples = tabentry->n_dead_tuples;
anltuples = tabentry->n_live_tuples + tabentry->n_dead_tuples -
tabentry->last_anl_tuples;
vacthresh = (float4) vac_base_thresh + vac_scale_factor * reltuples;
anlthresh = (float4) anl_base_thresh + anl_scale_factor * reltuples;
/*
* Note that we don't need to take special consideration for stat
* reset, because if that happens, the last vacuum and analyze counts
* will be reset too.
*/
elog(DEBUG3, "%s: vac: %.0f (threshold %.0f), anl: %.0f (threshold %.0f)",
NameStr(classForm->relname),
vactuples, vacthresh, anltuples, anlthresh);
/* Determine if this table needs vacuum or analyze. */
*dovacuum = force_vacuum || (vactuples > vacthresh);
*doanalyze = (anltuples > anlthresh);
}
else
{
/*
* Skip a table not found in stat hash, unless we have to force vacuum
* for anti-wrap purposes. If it's not acted upon, there's no need to
* vacuum it.
*/
*dovacuum = force_vacuum;
*doanalyze = false;
}
/* ANALYZE refuses to work with pg_statistics */
if (relid == StatisticRelationId)
*doanalyze = false;
}
/*
* autovacuum_do_vac_analyze
* Vacuum and/or analyze the specified table
*/
static void
autovacuum_do_vac_analyze(autovac_table *tab,
BufferAccessStrategy bstrategy)
{
VacuumStmt vacstmt;
/* Set up command parameters --- use a local variable instead of palloc */
MemSet(&vacstmt, 0, sizeof(vacstmt));
vacstmt.type = T_VacuumStmt;
vacstmt.vacuum = tab->at_dovacuum;
vacstmt.full = false;
vacstmt.analyze = tab->at_doanalyze;
vacstmt.freeze_min_age = tab->at_freeze_min_age;
vacstmt.scan_all = tab->at_wraparound;
vacstmt.verbose = false;
vacstmt.relation = NULL; /* not used since we pass a relid */
vacstmt.va_cols = NIL;
/* Let pgstat know what we're doing */
autovac_report_activity(tab);
vacuum(&vacstmt, tab->at_relid, false, bstrategy, tab->at_wraparound, true);
}
/*
* autovac_report_activity
* Report to pgstat what autovacuum is doing
*
* We send a SQL string corresponding to what the user would see if the
* equivalent command was to be issued manually.
*
* Note we assume that we are going to report the next command as soon as we're
* done with the current one, and exit right after the last one, so we don't
* bother to report "<IDLE>" or some such.
*/
static void
autovac_report_activity(autovac_table *tab)
{
#define MAX_AUTOVAC_ACTIV_LEN (NAMEDATALEN * 2 + 56)
char activity[MAX_AUTOVAC_ACTIV_LEN];
int len;
/* Report the command and possible options */
if (tab->at_dovacuum)
snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
"autovacuum: VACUUM%s",
tab->at_doanalyze ? " ANALYZE" : "");
else
snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
"autovacuum: ANALYZE");
/*
* Report the qualified name of the relation.
*/
len = strlen(activity);
snprintf(activity + len, MAX_AUTOVAC_ACTIV_LEN - len,
" %s.%s%s", tab->at_nspname, tab->at_relname,
tab->at_wraparound ? " (to prevent wraparound)" : "");
/* Set statement_timestamp() to current time for pg_stat_activity */
SetCurrentStatementStartTimestamp();
pgstat_report_activity(activity);
}
/*
* AutoVacuumingActive
* Check GUC vars and report whether the autovacuum process should be
* running.
*/
bool
AutoVacuumingActive(void)
{
if (!autovacuum_start_daemon || !pgstat_track_counts)
return false;
return true;
}
/*
* autovac_init
* This is called at postmaster initialization.
*
* All we do here is annoy the user if he got it wrong.
*/
void
autovac_init(void)
{
if (autovacuum_start_daemon && !pgstat_track_counts)
ereport(WARNING,
(errmsg("autovacuum not started because of misconfiguration"),
errhint("Enable the \"track_counts\" option.")));
}
/*
* IsAutoVacuum functions
* Return whether this is either a launcher autovacuum process or a worker
* process.
*/
bool
IsAutoVacuumLauncherProcess(void)
{
return am_autovacuum_launcher;
}
bool
IsAutoVacuumWorkerProcess(void)
{
return am_autovacuum_worker;
}
/*
* AutoVacuumShmemSize
* Compute space needed for autovacuum-related shared memory
*/
Size
AutoVacuumShmemSize(void)
{
Size size;
/*
* Need the fixed struct and the array of WorkerInfoData.
*/
size = sizeof(AutoVacuumShmemStruct);
size = MAXALIGN(size);
size = add_size(size, mul_size(autovacuum_max_workers,
sizeof(WorkerInfoData)));
return size;
}
/*
* AutoVacuumShmemInit
* Allocate and initialize autovacuum-related shared memory
*/
void
AutoVacuumShmemInit(void)
{
bool found;
AutoVacuumShmem = (AutoVacuumShmemStruct *)
ShmemInitStruct("AutoVacuum Data",
AutoVacuumShmemSize(),
&found);
if (AutoVacuumShmem == NULL)
ereport(FATAL,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("not enough shared memory for autovacuum")));
if (!IsUnderPostmaster)
{
WorkerInfo worker;
int i;
Assert(!found);
AutoVacuumShmem->av_launcherpid = 0;
AutoVacuumShmem->av_freeWorkers = NULL;
SHMQueueInit(&AutoVacuumShmem->av_runningWorkers);
AutoVacuumShmem->av_startingWorker = NULL;
worker = (WorkerInfo) ((char *) AutoVacuumShmem +
MAXALIGN(sizeof(AutoVacuumShmemStruct)));
/* initialize the WorkerInfo free list */
for (i = 0; i < autovacuum_max_workers; i++)
{
worker[i].wi_links.next = (SHM_QUEUE *) AutoVacuumShmem->av_freeWorkers;
AutoVacuumShmem->av_freeWorkers = &worker[i];
}
}
else
Assert(found);
}
/*
* autovac_refresh_stats
* Refresh pgstats data for an autovacuum process
*
* Cause the next pgstats read operation to obtain fresh data, but throttle
* such refreshing in the autovacuum launcher. This is mostly to avoid
* rereading the pgstats files too many times in quick succession when there
* are many databases.
*
* Note: we avoid throttling in the autovac worker, as it would be
* counterproductive in the recheck logic.
*/
static void
autovac_refresh_stats(void)
{
if (IsAutoVacuumLauncherProcess())
{
static TimestampTz last_read = 0;
TimestampTz current_time;
current_time = GetCurrentTimestamp();
if (!TimestampDifferenceExceeds(last_read, current_time,
STATS_READ_DELAY))
return;
last_read = current_time;
}
pgstat_clear_snapshot();
}
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