/*-------------------------------------------------------------------------
*
* 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 SIGUSR2 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) 1996-2021, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/postmaster/autovacuum.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <signal.h>
#include <sys/time.h>
#include <unistd.h>
#include "access/heapam.h"
#include "access/htup_details.h"
#include "access/multixact.h"
#include "access/reloptions.h"
#include "access/tableam.h"
#include "access/transam.h"
#include "access/xact.h"
#include "catalog/dependency.h"
#include "catalog/namespace.h"
#include "catalog/pg_database.h"
#include "commands/dbcommands.h"
#include "commands/vacuum.h"
#include "lib/ilist.h"
#include "libpq/pqsignal.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "pgstat.h"
#include "postmaster/autovacuum.h"
#include "postmaster/fork_process.h"
#include "postmaster/interrupt.h"
#include "postmaster/postmaster.h"
#include "storage/bufmgr.h"
#include "storage/ipc.h"
#include "storage/latch.h"
#include "storage/lmgr.h"
#include "storage/pmsignal.h"
#include "storage/proc.h"
#include "storage/procsignal.h"
#include "storage/sinvaladt.h"
#include "storage/smgr.h"
#include "tcop/tcopprot.h"
#include "utils/fmgroids.h"
#include "utils/fmgrprotos.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/ps_status.h"
#include "utils/rel.h"
#include "utils/snapmgr.h"
#include "utils/syscache.h"
#include "utils/timeout.h"
#include "utils/timestamp.h"
/*
* GUC parameters
*/
bool autovacuum_start_daemon = false;
int autovacuum_max_workers;
int autovacuum_work_mem = -1;
int autovacuum_naptime;
int autovacuum_vac_thresh;
double autovacuum_vac_scale;
int autovacuum_vac_ins_thresh;
double autovacuum_vac_ins_scale;
int autovacuum_anl_thresh;
double autovacuum_anl_scale;
int autovacuum_freeze_max_age;
int autovacuum_multixact_freeze_max_age;
double 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
/* the minimum allowed time between two awakenings of the launcher */
#define MIN_AUTOVAC_SLEEPTIME 100.0 /* milliseconds */
#define MAX_AUTOVAC_SLEEPTIME 300 /* seconds */
/* 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_SIGUSR2 = false;
/* Comparison points for determining whether freeze_max_age is exceeded */
static TransactionId recentXid;
static MultiXactId recentMulti;
/* Default freeze ages to use for autovacuum (varies by database) */
static int default_freeze_min_age;
static int default_freeze_table_age;
static int default_multixact_freeze_min_age;
static int default_multixact_freeze_table_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;
dlist_node adl_node;
} avl_dbase;
/* struct to keep track of databases in worker */
typedef struct avw_dbase
{
Oid adw_datid;
char *adw_name;
TransactionId adw_frozenxid;
MultiXactId adw_minmulti;
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;
bool ar_hasrelopts;
AutoVacOpts ar_reloptions; /* copy of AutoVacOpts from the main table's
* reloptions, or NULL if none */
} av_relation;
/* struct to keep track of tables to vacuum and/or analyze, after rechecking */
typedef struct autovac_table
{
Oid at_relid;
VacuumParams at_params;
double at_vacuum_cost_delay;
int at_vacuum_cost_limit;
bool at_dobalance;
bool at_sharedrel;
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, if any
* wi_sharedrel flag indicating whether table is marked relisshared
* 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 and
* wi_sharedrel which are protected by AutovacuumScheduleLock (note these
* two fields are read-only for everyone except that worker itself).
*-------------
*/
typedef struct WorkerInfoData
{
dlist_node wi_links;
Oid wi_dboid;
Oid wi_tableoid;
PGPROC *wi_proc;
TimestampTz wi_launchtime;
bool wi_dobalance;
bool wi_sharedrel;
double 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;
/*
* Autovacuum workitem array, stored in AutoVacuumShmem->av_workItems. This
* list is mostly protected by AutovacuumLock, except that if an item is
* marked 'active' other processes must not modify the work-identifying
* members.
*/
typedef struct AutoVacuumWorkItem
{
AutoVacuumWorkItemType avw_type;
bool avw_used; /* below data is valid */
bool avw_active; /* being processed */
Oid avw_database;
Oid avw_relation;
BlockNumber avw_blockNumber;
} AutoVacuumWorkItem;
#define NUM_WORKITEMS 256
/*-------------
* 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)
* av_workItems work item array
*
* 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;
dlist_head av_freeWorkers;
dlist_head av_runningWorkers;
WorkerInfo av_startingWorker;
AutoVacuumWorkItem av_workItems[NUM_WORKITEMS];
} AutoVacuumShmemStruct;
static AutoVacuumShmemStruct *AutoVacuumShmem;
/*
* the database list (of avl_dbase elements) in the launcher, and the context
* that contains it
*/
static dlist_head DatabaseList = DLIST_STATIC_INIT(DatabaseList);
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[]) pg_attribute_noreturn();
NON_EXEC_STATIC void AutoVacLauncherMain(int argc, char *argv[]) pg_attribute_noreturn();
static Oid do_start_worker(void);
static void HandleAutoVacLauncherInterrupts(void);
static void AutoVacLauncherShutdown(void) pg_attribute_noreturn();
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,
TupleDesc pg_class_desc,
int effective_multixact_freeze_max_age);
static void recheck_relation_needs_vacanalyze(Oid relid, AutoVacOpts *avopts,
Form_pg_class classForm,
int effective_multixact_freeze_max_age,
bool *dovacuum, bool *doanalyze, bool *wraparound);
static void relation_needs_vacanalyze(Oid relid, AutoVacOpts *relopts,
Form_pg_class classForm,
PgStat_StatTabEntry *tabentry,
int effective_multixact_freeze_max_age,
bool *dovacuum, bool *doanalyze, bool *wraparound);
static void autovacuum_do_vac_analyze(autovac_table *tab,
BufferAccessStrategy bstrategy);
static AutoVacOpts *extract_autovac_opts(HeapTuple tup,
TupleDesc pg_class_desc);
static PgStat_StatTabEntry *get_pgstat_tabentry_relid(Oid relid, bool isshared,
PgStat_StatDBEntry *shared,
PgStat_StatDBEntry *dbentry);
static void perform_work_item(AutoVacuumWorkItem *workitem);
static void autovac_report_activity(autovac_table *tab);
static void autovac_report_workitem(AutoVacuumWorkItem *workitem,
const char *nspname, const char *relname);
static void avl_sigusr2_handler(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 ... */
InitPostmasterChild();
/* Close the postmaster's sockets */
ClosePostmasterPorts(false);
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;
am_autovacuum_launcher = true;
MyBackendType = B_AUTOVAC_LAUNCHER;
init_ps_display(NULL);
ereport(DEBUG1,
(errmsg_internal("autovacuum launcher started")));
if (PostAuthDelay)
pg_usleep(PostAuthDelay * 1000000L);
SetProcessingMode(InitProcessing);
/*
* 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.
*/
pqsignal(SIGHUP, SignalHandlerForConfigReload);
pqsignal(SIGINT, StatementCancelHandler);
pqsignal(SIGTERM, SignalHandlerForShutdownRequest);
/* SIGQUIT handler was already set up by InitPostmasterChild */
InitializeTimeouts(); /* establishes SIGALRM handler */
pqsignal(SIGPIPE, SIG_IGN);
pqsignal(SIGUSR1, procsignal_sigusr1_handler);
pqsignal(SIGUSR2, avl_sigusr2_handler);
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
InitPostgres(NULL, InvalidOid, NULL, InvalidOid, NULL, false);
SetProcessingMode(NormalProcessing);
/*
* 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_SIZES);
MemoryContextSwitchTo(AutovacMemCxt);
/*
* If an exception is encountered, processing resumes here.
*
* This code is a stripped down version of PostgresMain error recovery.
*
* Note that we use sigsetjmp(..., 1), so that the prevailing signal mask
* (to wit, BlockSig) will be restored when longjmp'ing to here. Thus,
* signals other than SIGQUIT will be blocked until we complete error
* recovery. It might seem that this policy makes the HOLD_INTERRUPTS()
* call redundant, but it is not since InterruptPending might be set
* already.
*/
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();
/* Forget any pending QueryCancel or timeout request */
disable_all_timeouts(false);
QueryCancelPending = false; /* second to avoid race condition */
/* Report the error to the server log */
EmitErrorReport();
/* Abort the current transaction in order to recover */
AbortCurrentTransaction();
/*
* Release any other resources, for the case where we were not in a
* transaction.
*/
LWLockReleaseAll();
pgstat_report_wait_end();
AbortBufferIO();
UnlockBuffers();
/* this is probably dead code, but let's be safe: */
if (AuxProcessResourceOwner)
ReleaseAuxProcessResources(false);
AtEOXact_Buffers(false);
AtEOXact_SMgr();
AtEOXact_Files(false);
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;
dlist_init(&DatabaseList);
/*
* 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();
/* if in shutdown mode, no need for anything further; just go away */
if (ShutdownRequestPending)
AutoVacLauncherShutdown();
/*
* 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;
/* must unblock signals before calling rebuild_database_list */
PG_SETMASK(&UnBlockSig);
/*
* Set always-secure search path. Launcher doesn't connect to a database,
* so this has no effect.
*/
SetConfigOption("search_path", "", PGC_SUSET, PGC_S_OVERRIDE);
/*
* 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 settable timeouts off to avoid letting these settings prevent
* regular maintenance from being executed.
*/
SetConfigOption("statement_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
SetConfigOption("lock_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
SetConfigOption("idle_in_transaction_session_timeout", "0",
PGC_SUSET, PGC_S_OVERRIDE);
/*
* Force default_transaction_isolation to READ COMMITTED. We don't want
* to pay the overhead of serializable mode, nor add any risk of causing
* deadlocks or delaying other transactions.
*/
SetConfigOption("default_transaction_isolation", "read committed",
PGC_SUSET, PGC_S_OVERRIDE);
/*
* In emergency mode, just start a worker (unless shutdown was requested)
* and go away.
*/
if (!AutoVacuumingActive())
{
if (!ShutdownRequestPending)
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);
/* loop until shutdown request */
while (!ShutdownRequestPending)
{
struct timeval nap;
TimestampTz current_time = 0;
bool can_launch;
/*
* This loop is a bit different from the normal use of WaitLatch,
* because we'd like to sleep before the first launch of a child
* process. So it's WaitLatch, then ResetLatch, then check for
* wakening conditions.
*/
launcher_determine_sleep(!dlist_is_empty(&AutoVacuumShmem->av_freeWorkers),
false, &nap);
/*
* Wait until naptime expires or we get some type of signal (all the
* signal handlers will wake us by calling SetLatch).
*/
(void) WaitLatch(MyLatch,
WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
(nap.tv_sec * 1000L) + (nap.tv_usec / 1000L),
WAIT_EVENT_AUTOVACUUM_MAIN);
ResetLatch(MyLatch);
HandleAutoVacLauncherInterrupts();
/*
* a worker finished, or postmaster signaled failure to start a worker
*/
if (got_SIGUSR2)
{
got_SIGUSR2 = 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(1000000L); /* 1s */
SendPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER);
continue;
}
}
/*
* There are some conditions that we need to check before trying to
* start a worker. First, we need to make sure that there is a worker
* 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 = !dlist_is_empty(&AutoVacuumShmem->av_freeWorkers);
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_sharedrel = false;
worker->wi_proc = NULL;
worker->wi_launchtime = 0;
dlist_push_head(&AutoVacuumShmem->av_freeWorkers,
&worker->wi_links);
AutoVacuumShmem->av_startingWorker = NULL;
elog(WARNING, "worker took too long to start; canceled");
}
}
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 */
if (dlist_is_empty(&DatabaseList))
{
/*
* 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);
}
else
{
/*
* because rebuild_database_list constructs a list with most
* distant adl_next_worker first, we obtain our database from the
* tail of the list.
*/
avl_dbase *avdb;
avdb = dlist_tail_element(avl_dbase, adl_node, &DatabaseList);
/*
* 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);
}
}
AutoVacLauncherShutdown();
}
/*
* Process any new interrupts.
*/
static void
HandleAutoVacLauncherInterrupts(void)
{
/* the normal shutdown case */
if (ShutdownRequestPending)
AutoVacLauncherShutdown();
if (ConfigReloadPending)
{
ConfigReloadPending = false;
ProcessConfigFile(PGC_SIGHUP);
/* shutdown requested in config file? */
if (!AutoVacuumingActive())
AutoVacLauncherShutdown();
/* 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);
}
/* Process barrier events */
if (ProcSignalBarrierPending)
ProcessProcSignalBarrier();
/* Process sinval catchup interrupts that happened while sleeping */
ProcessCatchupInterrupt();
}
/*
* Perform a normal exit from the autovac launcher.
*/
static void
AutoVacLauncherShutdown(void)
{
ereport(DEBUG1,
(errmsg_internal("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)
{
/*
* 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 (!dlist_is_empty(&DatabaseList))
{
TimestampTz current_time = GetCurrentTimestamp();
TimestampTz next_wakeup;
avl_dbase *avdb;
long secs;
int usecs;
avdb = dlist_tail_element(avl_dbase, adl_node, &DatabaseList);
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;
}
/* The smallest time we'll allow the launcher to sleep. */
if (nap->tv_sec <= 0 && nap->tv_usec <= MIN_AUTOVAC_SLEEPTIME * 1000)
{
nap->tv_sec = 0;
nap->tv_usec = MIN_AUTOVAC_SLEEPTIME * 1000;
}
/*
* If the sleep time is too large, clamp it to an arbitrary maximum (plus
* any fractional seconds, for simplicity). This avoids an essentially
* infinite sleep in strange cases like the system clock going backwards a
* few years.
*/
if (nap->tv_sec > MAX_AUTOVAC_SLEEPTIME)
nap->tv_sec = MAX_AUTOVAC_SLEEPTIME;
}
/*
* 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;
dlist_iter iter;
/* use fresh stats */
autovac_refresh_stats();
newcxt = AllocSetContextCreate(AutovacMemCxt,
"AV dblist",
ALLOCSET_DEFAULT_SIZES);
tmpcxt = AllocSetContextCreate(newcxt,
"tmp AV dblist",
ALLOCSET_DEFAULT_SIZES);
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.hcxt = tmpcxt;
dbhash = hash_create("db hash", 20, &hctl, /* magic number here FIXME */
HASH_ELEM | HASH_BLOBS | 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 */
dlist_foreach(iter, &DatabaseList)
{
avl_dbase *avdb = dlist_container(avl_dbase, adl_node, iter.cur);
avl_dbase *db;
bool found;
PgStat_StatDBEntry *entry;
/*
* 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);
dlist_init(&DatabaseList);
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);
/*
* Determine the time interval between databases in the schedule. If
* we see that the configured naptime would take us to sleep times
* lower than our min sleep time (which launcher_determine_sleep is
* coded not to allow), silently use a larger naptime (but don't touch
* the GUC variable).
*/
millis_increment = 1000.0 * autovacuum_naptime / nelems;
if (millis_increment <= MIN_AUTOVAC_SLEEPTIME)
millis_increment = MIN_AUTOVAC_SLEEPTIME * 1.1;
current_time = GetCurrentTimestamp();
/*
* move the elements from the array into the dlist, setting the
* next_worker while walking the array
*/
for (i = 0; i < nelems; i++)
{
avl_dbase *db = &(dbary[i]);
current_time = TimestampTzPlusMilliseconds(current_time,
millis_increment);
db->adl_next_worker = current_time;
/* later elements should go closer to the head of the list */
dlist_push_head(&DatabaseList, &db->adl_node);
}
}
/* 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 (((const avl_dbase *) a)->adl_score == ((const avl_dbase *) b)->adl_score)
return 0;
else
return (((const avl_dbase *) a)->adl_score < ((const 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;
MultiXactId multiForceLimit;
bool for_xid_wrap;
bool for_multi_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 (dlist_is_empty(&AutoVacuumShmem->av_freeWorkers))
{
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_SIZES);
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 = ReadNextTransactionId();
xidForceLimit = recentXid - autovacuum_freeze_max_age;
/* ensure it's a "normal" XID, else TransactionIdPrecedes misbehaves */
/* this can cause the limit to go backwards by 3, but that's OK */
if (xidForceLimit < FirstNormalTransactionId)
xidForceLimit -= FirstNormalTransactionId;
/* Also determine the oldest datminmxid we will consider. */
recentMulti = ReadNextMultiXactId();
multiForceLimit = recentMulti - MultiXactMemberFreezeThreshold();
if (multiForceLimit < FirstMultiXactId)
multiForceLimit -= FirstMultiXactId;
/*
* 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 Xid wraparound is
* found, we pick the one with oldest datfrozenxid, independently of
* autovacuum times; similarly we pick the one with the oldest datminmxid
* if any is in MultiXactId wraparound. Note that those in Xid wraparound
* danger are given more priority than those in multi wraparound danger.
*
* 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;
for_multi_wrap = false;
current_time = GetCurrentTimestamp();
foreach(cell, dblist)
{
avw_dbase *tmp = lfirst(cell);
dlist_iter iter;
/* 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 */
else if (MultiXactIdPrecedes(tmp->adw_minmulti, multiForceLimit))
{
if (avdb == NULL ||
MultiXactIdPrecedes(tmp->adw_minmulti, avdb->adw_minmulti))
avdb = tmp;
for_multi_wrap = true;
continue;
}
else if (for_multi_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;
dlist_reverse_foreach(iter, &DatabaseList)
{
avl_dbase *dbp = dlist_container(avl_dbase, adl_node, iter.cur);
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;
}
}
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;
dlist_node *wptr;
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
/*
* Get a worker entry from the freelist. We checked above, so there
* really should be a free slot.
*/
wptr = dlist_pop_head_node(&AutoVacuumShmem->av_freeWorkers);
worker = dlist_container(WorkerInfoData, wi_links, wptr);
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;
dlist_iter iter;
dbid = do_start_worker();
if (OidIsValid(dbid))
{
bool found = false;
/*
* Walk the database list and update the corresponding entry. If the
* database is not on the list, we'll recreate the list.
*/
dlist_foreach(iter, &DatabaseList)
{
avl_dbase *avdb = dlist_container(avl_dbase, adl_node, iter.cur);
if (avdb->adl_datid == dbid)
{
found = true;
/*
* 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);
dlist_move_head(&DatabaseList, iter.cur);
break;
}
}
/*
* 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 (!found)
rebuild_database_list(dbid);
}
}
/*
* Called from postmaster to signal a failure to fork a process to become
* worker. The postmaster should kill(SIGUSR2) the launcher shortly
* after calling this function.
*/
void
AutoVacWorkerFailed(void)
{
AutoVacuumShmem->av_signal[AutoVacForkFailed] = true;
}
/* SIGUSR2: a worker is up and running, or just finished, or failed to fork */
static void
avl_sigusr2_handler(SIGNAL_ARGS)
{
int save_errno = errno;
got_SIGUSR2 = true;
SetLatch(MyLatch);
errno = save_errno;
}
/********************************************************************
* 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 ... */
InitPostmasterChild();
/* Close the postmaster's sockets */
ClosePostmasterPorts(false);
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;
am_autovacuum_worker = true;
MyBackendType = B_AUTOVAC_WORKER;
init_ps_display(NULL);
SetProcessingMode(InitProcessing);
/*
* 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.
*/
pqsignal(SIGHUP, SignalHandlerForConfigReload);
/*
* SIGINT is used to signal canceling the current table's vacuum; SIGTERM
* means abort and exit cleanly, and SIGQUIT means abandon ship.
*/
pqsignal(SIGINT, StatementCancelHandler);
pqsignal(SIGTERM, die);
/* SIGQUIT handler was already set up by InitPostmasterChild */
InitializeTimeouts(); /* establishes SIGALRM handler */
pqsignal(SIGPIPE, SIG_IGN);
pqsignal(SIGUSR1, procsignal_sigusr1_handler);
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.
*
* Unlike most auxiliary processes, we don't attempt to continue
* processing after an error; we just clean up and exit. The autovac
* launcher is responsible for spawning another worker later.
*
* Note that we use sigsetjmp(..., 1), so that the prevailing signal mask
* (to wit, BlockSig) will be restored when longjmp'ing to here. Thus,
* signals other than SIGQUIT will be blocked until we exit. It might
* seem that this policy makes the HOLD_INTERRUPTS() call redundant, but
* it is not since InterruptPending might be set already.
*/
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();
/*
* 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);
/*
* Set always-secure search path, so malicious users can't redirect user
* code (e.g. pg_index.indexprs). (That code runs in a
* SECURITY_RESTRICTED_OPERATION sandbox, so malicious users could not
* take control of the entire autovacuum worker in any case.)
*/
SetConfigOption("search_path", "", PGC_SUSET, PGC_S_OVERRIDE);
/*
* 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 settable timeouts off to avoid letting these settings prevent
* regular maintenance from being executed.
*/
SetConfigOption("statement_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
SetConfigOption("lock_timeout", "0", PGC_SUSET, PGC_S_OVERRIDE);
SetConfigOption("idle_in_transaction_session_timeout", "0",
PGC_SUSET, PGC_S_OVERRIDE);
/*
* Force default_transaction_isolation to READ COMMITTED. We don't want
* to pay the overhead of serializable mode, nor add any risk of causing
* deadlocks or delaying other transactions.
*/
SetConfigOption("default_transaction_isolation", "read committed",
PGC_SUSET, PGC_S_OVERRIDE);
/*
* Force synchronous replication off to allow regular maintenance even if
* we are waiting for standbys to connect. This is important to ensure we
* aren't blocked from performing anti-wraparound tasks.
*/
if (synchronous_commit > SYNCHRONOUS_COMMIT_LOCAL_FLUSH)
SetConfigOption("synchronous_commit", "local",
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 */
dlist_push_head(&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, SIGUSR2);
}
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[NAMEDATALEN];
/*
* 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, InvalidOid, dbname, false);
SetProcessingMode(NormalProcessing);
set_ps_display(dbname);
ereport(DEBUG1,
(errmsg_internal("autovacuum: processing database \"%s\"", dbname)));
if (PostAuthDelay)
pg_usleep(PostAuthDelay * 1000000L);
/* And do an appropriate amount of work */
recentXid = ReadNextTransactionId();
recentMulti = ReadNextMultiXactId();
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 us 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;
dlist_delete(&MyWorkerInfo->wi_links);
MyWorkerInfo->wi_dboid = InvalidOid;
MyWorkerInfo->wi_tableoid = InvalidOid;
MyWorkerInfo->wi_sharedrel = false;
MyWorkerInfo->wi_proc = NULL;
MyWorkerInfo->wi_launchtime = 0;
MyWorkerInfo->wi_dobalance = false;
MyWorkerInfo->wi_cost_delay = 0;
MyWorkerInfo->wi_cost_limit = 0;
MyWorkerInfo->wi_cost_limit_base = 0;
dlist_push_head(&AutoVacuumShmem->av_freeWorkers,
&MyWorkerInfo->wi_links);
/* 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 worker.
*
* Caller must hold the AutovacuumLock in exclusive mode.
*/
static void
autovac_balance_cost(void)
{
/*
* The idea here is that we ration out I/O equally. The amount of I/O
* that a worker can consume is determined by cost_limit/cost_delay, so we
* try to equalize those ratios rather than the raw limit settings.
*
* 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);
double vac_cost_delay = (autovacuum_vac_cost_delay >= 0 ?
autovacuum_vac_cost_delay : VacuumCostDelay);
double cost_total;
double cost_avail;
dlist_iter iter;
/* not set? nothing to do */
if (vac_cost_limit <= 0 || vac_cost_delay <= 0)
return;
/* calculate the total base cost limit of participating active workers */
cost_total = 0.0;
dlist_foreach(iter, &AutoVacuumShmem->av_runningWorkers)
{
WorkerInfo worker = dlist_container(WorkerInfoData, wi_links, iter.cur);
if (worker->wi_proc != NULL &&
worker->wi_dobalance &&
worker->wi_cost_limit_base > 0 && worker->wi_cost_delay > 0)
cost_total +=
(double) worker->wi_cost_limit_base / worker->wi_cost_delay;
}
/* there are no cost limits -- nothing to do */
if (cost_total <= 0)
return;
/*
* Adjust cost limit of each active worker to balance the total of cost
* limit to autovacuum_vacuum_cost_limit.
*/
cost_avail = (double) vac_cost_limit / vac_cost_delay;
dlist_foreach(iter, &AutoVacuumShmem->av_runningWorkers)
{
WorkerInfo worker = dlist_container(WorkerInfoData, wi_links, iter.cur);
if (worker->wi_proc != NULL &&
worker->wi_dobalance &&
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 on the cost_limit, to avoid division-
* by-zero in the vacuum code. Also, in case of roundoff trouble
* in these calculations, let's be sure we don't ever set
* cost_limit to more than the base value.
*/
worker->wi_cost_limit = Max(Min(limit,
worker->wi_cost_limit_base),
1);
}
if (worker->wi_proc != NULL)
elog(DEBUG2, "autovac_balance_cost(pid=%d db=%u, rel=%u, dobalance=%s cost_limit=%d, cost_limit_base=%d, cost_delay=%g)",
worker->wi_proc->pid, worker->wi_dboid, worker->wi_tableoid,
worker->wi_dobalance ? "yes" : "no",
worker->wi_cost_limit, worker->wi_cost_limit_base,
worker->wi_cost_delay);
}
}
/*
* get_database_list
* Return a list of all databases found in pg_database.
*
* The list and associated data is allocated in the caller's memory context,
* which is in charge of ensuring that it's properly cleaned up afterwards.
*
* Note: this is the only function in which the autovacuum launcher uses a
* transaction. Although we aren't attached to any particular database and
* therefore can't access most catalogs, we do have enough infrastructure
* to do a seqscan on pg_database.
*/
static List *
get_database_list(void)
{
List *dblist = NIL;
Relation rel;
TableScanDesc scan;
HeapTuple tup;
MemoryContext resultcxt;
/* This is the context that we will allocate our output data in */
resultcxt = CurrentMemoryContext;
/*
* Start a transaction so we can access pg_database, and get a snapshot.
* We don't have a use for the snapshot itself, but we're interested in
* the secondary effect that it sets RecentGlobalXmin. (This is critical
* for anything that reads heap pages, because HOT may decide to prune
* them even if the process doesn't attempt to modify any tuples.)
*
* FIXME: This comment is inaccurate / the code buggy. A snapshot that is
* not pushed/active does not reliably prevent HOT pruning (->xmin could
* e.g. be cleared when cache invalidations are processed).
*/
StartTransactionCommand();
(void) GetTransactionSnapshot();
rel = table_open(DatabaseRelationId, AccessShareLock);
scan = table_beginscan_catalog(rel, 0, NULL);
while (HeapTupleIsValid(tup = heap_getnext(scan, ForwardScanDirection)))
{
Form_pg_database pgdatabase = (Form_pg_database) GETSTRUCT(tup);
avw_dbase *avdb;
MemoryContext oldcxt;
/*
* Allocate our results in the caller's context, not the
* transaction's. We do this inside the loop, and restore the original
* context at the end, so that leaky things like heap_getnext() are
* not called in a potentially long-lived context.
*/
oldcxt = MemoryContextSwitchTo(resultcxt);
avdb = (avw_dbase *) palloc(sizeof(avw_dbase));
avdb->adw_datid = pgdatabase->oid;
avdb->adw_name = pstrdup(NameStr(pgdatabase->datname));
avdb->adw_frozenxid = pgdatabase->datfrozenxid;
avdb->adw_minmulti = pgdatabase->datminmxid;
/* this gets set later: */
avdb->adw_entry = NULL;
dblist = lappend(dblist, avdb);
MemoryContextSwitchTo(oldcxt);
}
table_endscan(scan);
table_close(rel, AccessShareLock);
CommitTransactionCommand();
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;
HeapTuple tuple;
TableScanDesc relScan;
Form_pg_database dbForm;
List *table_oids = NIL;
List *orphan_oids = NIL;
HASHCTL ctl;
HTAB *table_toast_map;
ListCell *volatile cell;
PgStat_StatDBEntry *shared;
PgStat_StatDBEntry *dbentry;
BufferAccessStrategy bstrategy;
ScanKeyData key;
TupleDesc pg_class_desc;
int effective_multixact_freeze_max_age;
bool did_vacuum = false;
bool found_concurrent_worker = false;
int i;
/*
* 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_SIZES);
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();
/*
* Compute the multixact age for which freezing is urgent. This is
* normally autovacuum_multixact_freeze_max_age, but may be less if we are
* short of multixact member space.
*/
effective_multixact_freeze_max_age = MultiXactMemberFreezeThreshold();
/*
* Find the pg_database entry and select the default freeze ages. We use
* zero in template and nonconnectable databases, else the system-wide
* default.
*/
tuple = SearchSysCache1(DATABASEOID, ObjectIdGetDatum(MyDatabaseId));
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;
default_freeze_table_age = 0;
default_multixact_freeze_min_age = 0;
default_multixact_freeze_table_age = 0;
}
else
{
default_freeze_min_age = vacuum_freeze_min_age;
default_freeze_table_age = vacuum_freeze_table_age;
default_multixact_freeze_min_age = vacuum_multixact_freeze_min_age;
default_multixact_freeze_table_age = vacuum_multixact_freeze_table_age;
}
ReleaseSysCache(tuple);
/* StartTransactionCommand changed elsewhere */
MemoryContextSwitchTo(AutovacMemCxt);
/* The database hash where pgstat keeps shared relations */
shared = pgstat_fetch_stat_dbentry(InvalidOid);
classRel = table_open(RelationRelationId, AccessShareLock);
/* create a copy so we can use it after closing pg_class */
pg_class_desc = CreateTupleDescCopy(RelationGetDescr(classRel));
/* create hash table for toast <-> main relid mapping */
ctl.keysize = sizeof(Oid);
ctl.entrysize = sizeof(av_relation);
table_toast_map = hash_create("TOAST to main relid map",
100,
&ctl,
HASH_ELEM | HASH_BLOBS);
/*
* 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 materialized views, 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_class.reloptions 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.
*/
relScan = table_beginscan_catalog(classRel, 0, NULL);
/*
* 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);
PgStat_StatTabEntry *tabentry;
AutoVacOpts *relopts;
Oid relid;
bool dovacuum;
bool doanalyze;
bool wraparound;
if (classForm->relkind != RELKIND_RELATION &&
classForm->relkind != RELKIND_MATVIEW)
continue;
relid = classForm->oid;
/*
* Check if it is a temp table (presumably, of some other backend's).
* We cannot safely process other backends' temp tables.
*/
if (classForm->relpersistence == RELPERSISTENCE_TEMP)
{
/*
* We just ignore it if the owning backend is still active and
* using the temporary schema. Also, for safety, ignore it if the
* namespace doesn't exist or isn't a temp namespace after all.
*/
if (checkTempNamespaceStatus(classForm->relnamespace) == TEMP_NAMESPACE_IDLE)
{
/*
* The table seems to be orphaned -- although it might be that
* the owning backend has already deleted it and exited; our
* pg_class scan snapshot is not necessarily up-to-date
* anymore, so we could be looking at a committed-dead entry.
* Remember it so we can try to delete it later.
*/
orphan_oids = lappend_oid(orphan_oids, relid);
}
continue;
}
/* Fetch reloptions and the pgstat entry for this table */
relopts = extract_autovac_opts(tuple, pg_class_desc);
tabentry = get_pgstat_tabentry_relid(relid, classForm->relisshared,
shared, dbentry);
/* Check if it needs vacuum or analyze */
relation_needs_vacanalyze(relid, relopts, classForm, tabentry,
effective_multixact_freeze_max_age,
&dovacuum, &doanalyze, &wraparound);
/* Relations that need work are added to table_oids */
if (dovacuum || doanalyze)
table_oids = lappend_oid(table_oids, relid);
/*
* Remember TOAST associations for the second pass. Note: we must do
* this whether or not 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;
hentry->ar_hasrelopts = false;
if (relopts != NULL)
{
hentry->ar_hasrelopts = true;
memcpy(&hentry->ar_reloptions, relopts,
sizeof(AutoVacOpts));
}
}
}
}
table_endscan(relScan);
/* second pass: check TOAST tables */
ScanKeyInit(&key,
Anum_pg_class_relkind,
BTEqualStrategyNumber, F_CHAREQ,
CharGetDatum(RELKIND_TOASTVALUE));
relScan = table_beginscan_catalog(classRel, 1, &key);
while ((tuple = heap_getnext(relScan, ForwardScanDirection)) != NULL)
{
Form_pg_class classForm = (Form_pg_class) GETSTRUCT(tuple);
PgStat_StatTabEntry *tabentry;
Oid relid;
AutoVacOpts *relopts = NULL;
bool dovacuum;
bool doanalyze;
bool wraparound;
/*
* We cannot safely process other backends' temp tables, so skip 'em.
*/
if (classForm->relpersistence == RELPERSISTENCE_TEMP)
continue;
relid = classForm->oid;
/*
* fetch reloptions -- if this toast table does not have them, try the
* main rel
*/
relopts = extract_autovac_opts(tuple, pg_class_desc);
if (relopts == NULL)
{
av_relation *hentry;
bool found;
hentry = hash_search(table_toast_map, &relid, HASH_FIND, &found);
if (found && hentry->ar_hasrelopts)
relopts = &hentry->ar_reloptions;
}
/* Fetch the pgstat entry for this table */
tabentry = get_pgstat_tabentry_relid(relid, classForm->relisshared,
shared, dbentry);
relation_needs_vacanalyze(relid, relopts, classForm, tabentry,
effective_multixact_freeze_max_age,
&dovacuum, &doanalyze, &wraparound);
/* ignore analyze for toast tables */
if (dovacuum)
table_oids = lappend_oid(table_oids, relid);
}
table_endscan(relScan);
table_close(classRel, AccessShareLock);
/*
* Recheck orphan temporary tables, and if they still seem orphaned, drop
* them. We'll eat a transaction per dropped table, which might seem
* excessive, but we should only need to do anything as a result of a
* previous backend crash, so this should not happen often enough to
* justify "optimizing". Using separate transactions ensures that we
* don't bloat the lock table if there are many temp tables to be dropped,
* and it ensures that we don't lose work if a deletion attempt fails.
*/
foreach(cell, orphan_oids)
{
Oid relid = lfirst_oid(cell);
Form_pg_class classForm;
ObjectAddress object;
/*
* Check for user-requested abort.
*/
CHECK_FOR_INTERRUPTS();
/*
* Try to lock the table. If we can't get the lock immediately,
* somebody else is using (or dropping) the table, so it's not our
* concern anymore. Having the lock prevents race conditions below.
*/
if (!ConditionalLockRelationOid(relid, AccessExclusiveLock))
continue;
/*
* Re-fetch the pg_class tuple and re-check whether it still seems to
* be an orphaned temp table. If it's not there or no longer the same
* relation, ignore it.
*/
tuple = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relid));
if (!HeapTupleIsValid(tuple))
{
/* be sure to drop useless lock so we don't bloat lock table */
UnlockRelationOid(relid, AccessExclusiveLock);
continue;
}
classForm = (Form_pg_class) GETSTRUCT(tuple);
/*
* Make all the same tests made in the loop above. In event of OID
* counter wraparound, the pg_class entry we have now might be
* completely unrelated to the one we saw before.
*/
if (!((classForm->relkind == RELKIND_RELATION ||
classForm->relkind == RELKIND_MATVIEW) &&
classForm->relpersistence == RELPERSISTENCE_TEMP))
{
UnlockRelationOid(relid, AccessExclusiveLock);
continue;
}
if (checkTempNamespaceStatus(classForm->relnamespace) != TEMP_NAMESPACE_IDLE)
{
UnlockRelationOid(relid, AccessExclusiveLock);
continue;
}
/* OK, let's delete it */
ereport(LOG,
(errmsg("autovacuum: dropping orphan temp table \"%s.%s.%s\"",
get_database_name(MyDatabaseId),
get_namespace_name(classForm->relnamespace),
NameStr(classForm->relname))));
object.classId = RelationRelationId;
object.objectId = relid;
object.objectSubId = 0;
performDeletion(&object, DROP_CASCADE,
PERFORM_DELETION_INTERNAL |
PERFORM_DELETION_QUIETLY |
PERFORM_DELETION_SKIP_EXTENSIONS);
/*
* To commit the deletion, end current transaction and start a new
* one. Note this also releases the lock we took.
*/
CommitTransactionCommand();
StartTransactionCommand();
/* StartTransactionCommand changed current memory context */
MemoryContextSwitchTo(AutovacMemCxt);
}
/*
* 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_SIZES);
/*
* Perform operations on collected tables.
*/
foreach(cell, table_oids)
{
Oid relid = lfirst_oid(cell);
HeapTuple classTup;
autovac_table *tab;
bool isshared;
bool skipit;
double stdVacuumCostDelay;
int stdVacuumCostLimit;
dlist_iter iter;
CHECK_FOR_INTERRUPTS();
/*
* Check for config changes before processing each collected table.
*/
if (ConfigReloadPending)
{
ConfigReloadPending = false;
ProcessConfigFile(PGC_SIGHUP);
/*
* You might be tempted to bail out if we see autovacuum is now
* disabled. Must resist that temptation -- this might be a
* for-wraparound emergency worker, in which case that would be
* entirely inappropriate.
*/
}
/*
* Find out whether the table is shared or not. (It's slightly
* annoying to fetch the syscache entry just for this, but in typical
* cases it adds little cost because table_recheck_autovac would
* refetch the entry anyway. We could buy that back by copying the
* tuple here and passing it to table_recheck_autovac, but that
* increases the odds of that function working with stale data.)
*/
classTup = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
if (!HeapTupleIsValid(classTup))
continue; /* somebody deleted the rel, forget it */
isshared = ((Form_pg_class) GETSTRUCT(classTup))->relisshared;
ReleaseSysCache(classTup);
/*
* Hold schedule lock from here until we've claimed the table. We
* also need the AutovacuumLock to walk the worker array, but that one
* can just be a shared lock.
*/
LWLockAcquire(AutovacuumScheduleLock, LW_EXCLUSIVE);
LWLockAcquire(AutovacuumLock, LW_SHARED);
/*
* Check whether the table is being vacuumed concurrently by another
* worker.
*/
skipit = false;
dlist_foreach(iter, &AutoVacuumShmem->av_runningWorkers)
{
WorkerInfo worker = dlist_container(WorkerInfoData, wi_links, iter.cur);
/* ignore myself */
if (worker == MyWorkerInfo)
continue;
/* ignore workers in other databases (unless table is shared) */
if (!worker->wi_sharedrel && worker->wi_dboid != MyDatabaseId)
continue;
if (worker->wi_tableoid == relid)
{
skipit = true;
found_concurrent_worker = true;
break;
}
}
LWLockRelease(AutovacuumLock);
if (skipit)
{
LWLockRelease(AutovacuumScheduleLock);
continue;
}
/*
* Store the table's OID in shared memory before releasing the
* schedule lock, so that other workers don't try to vacuum it
* concurrently. (We claim it here so as not to hold
* AutovacuumScheduleLock while rechecking the stats.)
*/
MyWorkerInfo->wi_tableoid = relid;
MyWorkerInfo->wi_sharedrel = isshared;
LWLockRelease(AutovacuumScheduleLock);
/*
* 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, pg_class_desc,
effective_multixact_freeze_max_age);
if (tab == NULL)
{
/* someone else vacuumed the table, or it went away */
LWLockAcquire(AutovacuumScheduleLock, LW_EXCLUSIVE);
MyWorkerInfo->wi_tableoid = InvalidOid;
MyWorkerInfo->wi_sharedrel = false;
LWLockRelease(AutovacuumScheduleLock);
continue;
}
/*
* Remember the prevailing values of the vacuum cost GUCs. We have to
* restore these at the bottom of the loop, else we'll compute wrong
* values in the next iteration of autovac_balance_cost().
*/
stdVacuumCostDelay = VacuumCostDelay;
stdVacuumCostLimit = VacuumCostLimit;
/* Must hold AutovacuumLock while mucking with cost balance info */
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
/* advertise my cost delay parameters for the balancing algorithm */
MyWorkerInfo->wi_dobalance = tab->at_dobalance;
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();
/* set the active cost parameters from the result of that */
AutoVacuumUpdateDelay();
/* 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();
{
/* Use PortalContext for any per-table allocations */
MemoryContextSwitchTo(PortalContext);
/* have at it */
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_params.options & VACOPT_VACUUM)
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 ProcGlobal->statusFlags[i] too */
AbortOutOfAnyTransaction();
FlushErrorState();
MemoryContextResetAndDeleteChildren(PortalContext);
/* restart our transaction for the following operations */
StartTransactionCommand();
RESUME_INTERRUPTS();
}
PG_END_TRY();
/* Make sure we're back in AutovacMemCxt */
MemoryContextSwitchTo(AutovacMemCxt);
did_vacuum = true;
/* ProcGlobal->statusFlags[i] are reset at the next end of xact */
/* 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. We could, but intentionally
* don't, clear wi_cost_limit and friends --- this is on the
* assumption that we probably have more to do with similar cost
* settings, so we don't want to give up our share of I/O for a very
* short interval and thereby thrash the global balance.
*/
LWLockAcquire(AutovacuumScheduleLock, LW_EXCLUSIVE);
MyWorkerInfo->wi_tableoid = InvalidOid;
MyWorkerInfo->wi_sharedrel = false;
LWLockRelease(AutovacuumScheduleLock);
/* restore vacuum cost GUCs for the next iteration */
VacuumCostDelay = stdVacuumCostDelay;
VacuumCostLimit = stdVacuumCostLimit;
}
/*
* Perform additional work items, as requested by backends.
*/
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
for (i = 0; i < NUM_WORKITEMS; i++)
{
AutoVacuumWorkItem *workitem = &AutoVacuumShmem->av_workItems[i];
if (!workitem->avw_used)
continue;
if (workitem->avw_active)
continue;
if (workitem->avw_database != MyDatabaseId)
continue;
/* claim this one, and release lock while performing it */
workitem->avw_active = true;
LWLockRelease(AutovacuumLock);
perform_work_item(workitem);
/*
* Check for config changes before acquiring lock for further jobs.
*/
CHECK_FOR_INTERRUPTS();
if (ConfigReloadPending)
{
ConfigReloadPending = false;
ProcessConfigFile(PGC_SIGHUP);
}
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
/* and mark it done */
workitem->avw_active = false;
workitem->avw_used = false;
}
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_xact if possible. We
* only need to do this once, not after each table.
*
* Even if we didn't vacuum anything, it may still be important to do
* this, because one indirect effect of vac_update_datfrozenxid() is to
* update ShmemVariableCache->xidVacLimit. That might need to be done
* even if we haven't vacuumed anything, because relations with older
* relfrozenxid values or other databases with older datfrozenxid values
* might have been dropped, allowing xidVacLimit to advance.
*
* However, it's also important not to do this blindly in all cases,
* because when autovacuum=off this will restart the autovacuum launcher.
* If we're not careful, an infinite loop can result, where workers find
* no work to do and restart the launcher, which starts another worker in
* the same database that finds no work to do. To prevent that, we skip
* this if (1) we found no work to do and (2) we skipped at least one
* table due to concurrent autovacuum activity. In that case, the other
* worker has already done it, or will do so when it finishes.
*/
if (did_vacuum || !found_concurrent_worker)
vac_update_datfrozenxid();
/* Finally close out the last transaction. */
CommitTransactionCommand();
}
/*
* Execute a previously registered work item.
*/
static void
perform_work_item(AutoVacuumWorkItem *workitem)
{
char *cur_datname = NULL;
char *cur_nspname = NULL;
char *cur_relname = NULL;
/*
* Note we do not store table info in MyWorkerInfo, since this is not
* vacuuming proper.
*/
/*
* 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.
*/
Assert(CurrentMemoryContext == AutovacMemCxt);
cur_relname = get_rel_name(workitem->avw_relation);
cur_nspname = get_namespace_name(get_rel_namespace(workitem->avw_relation));
cur_datname = get_database_name(MyDatabaseId);
if (!cur_relname || !cur_nspname || !cur_datname)
goto deleted2;
autovac_report_workitem(workitem, cur_nspname, cur_relname);
/* clean up memory before each work item */
MemoryContextResetAndDeleteChildren(PortalContext);
/*
* We will abort the current work item if something errors out, and
* continue with the next one; in particular, this happens if we are
* interrupted with SIGINT. Note that this means that the work item list
* can be lossy.
*/
PG_TRY();
{
/* Use PortalContext for any per-work-item allocations */
MemoryContextSwitchTo(PortalContext);
/* have at it */
switch (workitem->avw_type)
{
case AVW_BRINSummarizeRange:
DirectFunctionCall2(brin_summarize_range,
ObjectIdGetDatum(workitem->avw_relation),
Int64GetDatum((int64) workitem->avw_blockNumber));
break;
default:
elog(WARNING, "unrecognized work item found: type %d",
workitem->avw_type);
break;
}
/*
* 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();
errcontext("processing work entry for relation \"%s.%s.%s\"",
cur_datname, cur_nspname, cur_relname);
EmitErrorReport();
/* this resets ProcGlobal->statusFlags[i] too */
AbortOutOfAnyTransaction();
FlushErrorState();
MemoryContextResetAndDeleteChildren(PortalContext);
/* restart our transaction for the following operations */
StartTransactionCommand();
RESUME_INTERRUPTS();
}
PG_END_TRY();
/* Make sure we're back in AutovacMemCxt */
MemoryContextSwitchTo(AutovacMemCxt);
/* We intentionally do not set did_vacuum here */
/* be tidy */
deleted2:
if (cur_datname)
pfree(cur_datname);
if (cur_nspname)
pfree(cur_nspname);
if (cur_relname)
pfree(cur_relname);
}
/*
* extract_autovac_opts
*
* Given a relation's pg_class tuple, return the AutoVacOpts portion of
* reloptions, if set; otherwise, return NULL.
*
* Note: callers do not have a relation lock on the table at this point,
* so the table could have been dropped, and its catalog rows gone, after
* we acquired the pg_class row. If pg_class had a TOAST table, this would
* be a risk; fortunately, it doesn't.
*/
static AutoVacOpts *
extract_autovac_opts(HeapTuple tup, TupleDesc pg_class_desc)
{
bytea *relopts;
AutoVacOpts *av;
Assert(((Form_pg_class) GETSTRUCT(tup))->relkind == RELKIND_RELATION ||
((Form_pg_class) GETSTRUCT(tup))->relkind == RELKIND_MATVIEW ||
((Form_pg_class) GETSTRUCT(tup))->relkind == RELKIND_TOASTVALUE);
relopts = extractRelOptions(tup, pg_class_desc, NULL);
if (relopts == NULL)
return NULL;
av = palloc(sizeof(AutoVacOpts));
memcpy(av, &(((StdRdOptions *) relopts)->autovacuum), sizeof(AutoVacOpts));
pfree(relopts);
return av;
}
/*
* 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,
TupleDesc pg_class_desc,
int effective_multixact_freeze_max_age)
{
Form_pg_class classForm;
HeapTuple classTup;
bool dovacuum;
bool doanalyze;
autovac_table *tab = NULL;
bool wraparound;
AutoVacOpts *avopts;
static bool reuse_stats = false;
/* fetch the relation's relcache entry */
classTup = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relid));
if (!HeapTupleIsValid(classTup))
return NULL;
classForm = (Form_pg_class) GETSTRUCT(classTup);
/*
* Get the applicable reloptions. If it is a TOAST table, try to get the
* main table reloptions if the toast table itself doesn't have.
*/
avopts = extract_autovac_opts(classTup, pg_class_desc);
if (classForm->relkind == RELKIND_TOASTVALUE &&
avopts == NULL && table_toast_map != NULL)
{
av_relation *hentry;
bool found;
hentry = hash_search(table_toast_map, &relid, HASH_FIND, &found);
if (found && hentry->ar_hasrelopts)
avopts = &hentry->ar_reloptions;
}
/*
* Reuse the stats to recheck whether a relation needs to be vacuumed or
* analyzed if it was reloaded before and has not been cleared yet. This
* is necessary to avoid frequent refresh of stats, especially when there
* are very large number of relations and the refresh can cause lots of
* overhead.
*
* If we determined that a relation needs to be vacuumed or analyzed,
* based on the old stats, we refresh stats and recheck the necessity
* again. Because a relation may have already been vacuumed or analyzed by
* someone since the last reload of stats.
*/
if (reuse_stats)
{
recheck_relation_needs_vacanalyze(relid, avopts, classForm,
effective_multixact_freeze_max_age,
&dovacuum, &doanalyze, &wraparound);
/* Quick exit if a relation doesn't need to be vacuumed or analyzed */
if (!doanalyze && !dovacuum)
{
heap_freetuple(classTup);
return NULL;
}
}
/* Use fresh stats and recheck again */
autovac_refresh_stats();
recheck_relation_needs_vacanalyze(relid, avopts, classForm,
effective_multixact_freeze_max_age,
&dovacuum, &doanalyze, &wraparound);
/* OK, it needs something done */
if (doanalyze || dovacuum)
{
int freeze_min_age;
int freeze_table_age;
int multixact_freeze_min_age;
int multixact_freeze_table_age;
int vac_cost_limit;
double vac_cost_delay;
int log_min_duration;
/*
* Calculate the vacuum cost parameters and the freeze ages. If there
* are options set in pg_class.reloptions, use them; in the case of a
* toast table, try the main table too. Otherwise use the GUC
* defaults, autovacuum's own first and plain vacuum second.
*/
/* -1 in autovac setting means use plain vacuum_cost_delay */
vac_cost_delay = (avopts && avopts->vacuum_cost_delay >= 0)
? avopts->vacuum_cost_delay
: (autovacuum_vac_cost_delay >= 0)
? autovacuum_vac_cost_delay
: VacuumCostDelay;
/* 0 or -1 in autovac setting means use plain vacuum_cost_limit */
vac_cost_limit = (avopts && avopts->vacuum_cost_limit > 0)
? avopts->vacuum_cost_limit
: (autovacuum_vac_cost_limit > 0)
? autovacuum_vac_cost_limit
: VacuumCostLimit;
/* -1 in autovac setting means use log_autovacuum_min_duration */
log_min_duration = (avopts && avopts->log_min_duration >= 0)
? avopts->log_min_duration
: Log_autovacuum_min_duration;
/* these do not have autovacuum-specific settings */
freeze_min_age = (avopts && avopts->freeze_min_age >= 0)
? avopts->freeze_min_age
: default_freeze_min_age;
freeze_table_age = (avopts && avopts->freeze_table_age >= 0)
? avopts->freeze_table_age
: default_freeze_table_age;
multixact_freeze_min_age = (avopts &&
avopts->multixact_freeze_min_age >= 0)
? avopts->multixact_freeze_min_age
: default_multixact_freeze_min_age;
multixact_freeze_table_age = (avopts &&
avopts->multixact_freeze_table_age >= 0)
? avopts->multixact_freeze_table_age
: default_multixact_freeze_table_age;
tab = palloc(sizeof(autovac_table));
tab->at_relid = relid;
tab->at_sharedrel = classForm->relisshared;
/* Note that this skips toast relations */
tab->at_params.options = (dovacuum ? VACOPT_VACUUM : 0) |
(doanalyze ? VACOPT_ANALYZE : 0) |
(!wraparound ? VACOPT_SKIP_LOCKED : 0);
/*
* index_cleanup and truncate are unspecified at first in autovacuum.
* They will be filled in with usable values using their reloptions
* (or reloption defaults) later.
*/
tab->at_params.index_cleanup = VACOPTVALUE_UNSPECIFIED;
tab->at_params.truncate = VACOPTVALUE_UNSPECIFIED;
/* As of now, we don't support parallel vacuum for autovacuum */
tab->at_params.nworkers = -1;
tab->at_params.freeze_min_age = freeze_min_age;
tab->at_params.freeze_table_age = freeze_table_age;
tab->at_params.multixact_freeze_min_age = multixact_freeze_min_age;
tab->at_params.multixact_freeze_table_age = multixact_freeze_table_age;
tab->at_params.is_wraparound = wraparound;
tab->at_params.log_min_duration = log_min_duration;
tab->at_vacuum_cost_limit = vac_cost_limit;
tab->at_vacuum_cost_delay = vac_cost_delay;
tab->at_relname = NULL;
tab->at_nspname = NULL;
tab->at_datname = NULL;
/*
* If any of the cost delay parameters has been set individually for
* this table, disable the balancing algorithm.
*/
tab->at_dobalance =
!(avopts && (avopts->vacuum_cost_limit > 0 ||
avopts->vacuum_cost_delay > 0));
/*
* When we decide to do vacuum or analyze, the existing stats cannot
* be reused in the next cycle because it's cleared at the end of
* vacuum or analyze (by AtEOXact_PgStat()).
*/
reuse_stats = false;
}
else
{
/*
* If neither vacuum nor analyze is necessary, the existing stats is
* not cleared and can be reused in the next cycle.
*/
reuse_stats = true;
}
heap_freetuple(classTup);
return tab;
}
/*
* recheck_relation_needs_vacanalyze
*
* Subroutine for table_recheck_autovac.
*
* Fetch the pgstat of a relation and recheck whether a relation
* needs to be vacuumed or analyzed.
*/
static void
recheck_relation_needs_vacanalyze(Oid relid,
AutoVacOpts *avopts,
Form_pg_class classForm,
int effective_multixact_freeze_max_age,
bool *dovacuum,
bool *doanalyze,
bool *wraparound)
{
PgStat_StatTabEntry *tabentry;
PgStat_StatDBEntry *shared = NULL;
PgStat_StatDBEntry *dbentry = NULL;
if (classForm->relisshared)
shared = pgstat_fetch_stat_dbentry(InvalidOid);
else
dbentry = pgstat_fetch_stat_dbentry(MyDatabaseId);
/* fetch the pgstat table entry */
tabentry = get_pgstat_tabentry_relid(relid, classForm->relisshared,
shared, dbentry);
relation_needs_vacanalyze(relid, avopts, classForm, tabentry,
effective_multixact_freeze_max_age,
dovacuum, doanalyze, wraparound);
/* ignore ANALYZE for toast tables */
if (classForm->relkind == RELKIND_TOASTVALUE)
*doanalyze = false;
}
/*
* 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 or multixact wraparound.
*
* relopts is a pointer to the AutoVacOpts options (either for itself in the
* case of a plain table, or for either itself or its parent table in the case
* of a TOAST table), NULL if none; tabentry is the pgstats entry, which can be
* NULL.
*
* 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, and if its relminmxid is more than
* multixact_freeze_max_age multixacts back.
*
* A table whose autovacuum_enabled option 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,
AutoVacOpts *relopts,
Form_pg_class classForm,
PgStat_StatTabEntry *tabentry,
int effective_multixact_freeze_max_age,
/* output params below */
bool *dovacuum,
bool *doanalyze,
bool *wraparound)
{
bool force_vacuum;
bool av_enabled;
float4 reltuples; /* pg_class.reltuples */
/* constants from reloptions or GUC variables */
int vac_base_thresh,
vac_ins_base_thresh,
anl_base_thresh;
float4 vac_scale_factor,
vac_ins_scale_factor,
anl_scale_factor;
/* thresholds calculated from above constants */
float4 vacthresh,
vacinsthresh,
anlthresh;
/* number of vacuum (resp. analyze) tuples at this time */
float4 vactuples,
instuples,
anltuples;
/* freeze parameters */
int freeze_max_age;
int multixact_freeze_max_age;
TransactionId xidForceLimit;
MultiXactId multiForceLimit;
AssertArg(classForm != NULL);
AssertArg(OidIsValid(relid));
/*
* Determine vacuum/analyze equation parameters. We have two possible
* sources: the passed reloptions (which could be a main table or a toast
* table), or the autovacuum GUC variables.
*/
/* -1 in autovac setting means use plain vacuum_scale_factor */
vac_scale_factor = (relopts && relopts->vacuum_scale_factor >= 0)
? relopts->vacuum_scale_factor
: autovacuum_vac_scale;
vac_base_thresh = (relopts && relopts->vacuum_threshold >= 0)
? relopts->vacuum_threshold
: autovacuum_vac_thresh;
vac_ins_scale_factor = (relopts && relopts->vacuum_ins_scale_factor >= 0)
? relopts->vacuum_ins_scale_factor
: autovacuum_vac_ins_scale;
/* -1 is used to disable insert vacuums */
vac_ins_base_thresh = (relopts && relopts->vacuum_ins_threshold >= -1)
? relopts->vacuum_ins_threshold
: autovacuum_vac_ins_thresh;
anl_scale_factor = (relopts && relopts->analyze_scale_factor >= 0)
? relopts->analyze_scale_factor
: autovacuum_anl_scale;
anl_base_thresh = (relopts && relopts->analyze_threshold >= 0)
? relopts->analyze_threshold
: autovacuum_anl_thresh;
freeze_max_age = (relopts && relopts->freeze_max_age >= 0)
? Min(relopts->freeze_max_age, autovacuum_freeze_max_age)
: autovacuum_freeze_max_age;
multixact_freeze_max_age = (relopts && relopts->multixact_freeze_max_age >= 0)
? Min(relopts->multixact_freeze_max_age, effective_multixact_freeze_max_age)
: effective_multixact_freeze_max_age;
av_enabled = (relopts ? relopts->enabled : true);
/* 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));
if (!force_vacuum)
{
multiForceLimit = recentMulti - multixact_freeze_max_age;
if (multiForceLimit < FirstMultiXactId)
multiForceLimit -= FirstMultiXactId;
force_vacuum = MultiXactIdIsValid(classForm->relminmxid) &&
MultiXactIdPrecedes(classForm->relminmxid, multiForceLimit);
}
*wraparound = force_vacuum;
/* User disabled it in pg_class.reloptions? (But ignore if at risk) */
if (!av_enabled && !force_vacuum)
{
*doanalyze = false;
*dovacuum = false;
return;
}
/*
* If we found the table in the stats hash, and autovacuum is currently
* enabled, make a threshold-based decision whether to vacuum and/or
* analyze. If autovacuum is currently disabled, we must be here for
* anti-wraparound vacuuming only, so don't vacuum (or analyze) anything
* that's not being forced.
*/
if (PointerIsValid(tabentry) && AutoVacuumingActive())
{
reltuples = classForm->reltuples;
vactuples = tabentry->n_dead_tuples;
instuples = tabentry->inserts_since_vacuum;
anltuples = tabentry->changes_since_analyze;
/* If the table hasn't yet been vacuumed, take reltuples as zero */
if (reltuples < 0)
reltuples = 0;
vacthresh = (float4) vac_base_thresh + vac_scale_factor * reltuples;
vacinsthresh = (float4) vac_ins_base_thresh + vac_ins_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.
*/
if (vac_ins_base_thresh >= 0)
elog(DEBUG3, "%s: vac: %.0f (threshold %.0f), ins: %.0f (threshold %.0f), anl: %.0f (threshold %.0f)",
NameStr(classForm->relname),
vactuples, vacthresh, instuples, vacinsthresh, anltuples, anlthresh);
else
elog(DEBUG3, "%s: vac: %.0f (threshold %.0f), ins: (disabled), anl: %.0f (threshold %.0f)",
NameStr(classForm->relname),
vactuples, vacthresh, anltuples, anlthresh);
/* Determine if this table needs vacuum or analyze. */
*dovacuum = force_vacuum || (vactuples > vacthresh) ||
(vac_ins_base_thresh >= 0 && instuples > vacinsthresh);
*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_statistic */
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)
{
RangeVar *rangevar;
VacuumRelation *rel;
List *rel_list;
/* Let pgstat know what we're doing */
autovac_report_activity(tab);
/* Set up one VacuumRelation target, identified by OID, for vacuum() */
rangevar = makeRangeVar(tab->at_nspname, tab->at_relname, -1);
rel = makeVacuumRelation(rangevar, tab->at_relid, NIL);
rel_list = list_make1(rel);
vacuum(rel_list, &tab->at_params, bstrategy, 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_params.options & VACOPT_VACUUM)
snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
"autovacuum: VACUUM%s",
tab->at_params.options & VACOPT_ANALYZE ? " 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_params.is_wraparound ? " (to prevent wraparound)" : "");
/* Set statement_timestamp() to current time for pg_stat_activity */
SetCurrentStatementStartTimestamp();
pgstat_report_activity(STATE_RUNNING, activity);
}
/*
* autovac_report_workitem
* Report to pgstat that autovacuum is processing a work item
*/
static void
autovac_report_workitem(AutoVacuumWorkItem *workitem,
const char *nspname, const char *relname)
{
char activity[MAX_AUTOVAC_ACTIV_LEN + 12 + 2];
char blk[12 + 2];
int len;
switch (workitem->avw_type)
{
case AVW_BRINSummarizeRange:
snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
"autovacuum: BRIN summarize");
break;
}
/*
* Report the qualified name of the relation, and the block number if any
*/
len = strlen(activity);
if (BlockNumberIsValid(workitem->avw_blockNumber))
snprintf(blk, sizeof(blk), " %u", workitem->avw_blockNumber);
else
blk[0] = '\0';
snprintf(activity + len, MAX_AUTOVAC_ACTIV_LEN - len,
" %s.%s%s", nspname, relname, blk);
/* Set statement_timestamp() to current time for pg_stat_activity */
SetCurrentStatementStartTimestamp();
pgstat_report_activity(STATE_RUNNING, 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;
}
/*
* Request one work item to the next autovacuum run processing our database.
* Return false if the request can't be recorded.
*/
bool
AutoVacuumRequestWork(AutoVacuumWorkItemType type, Oid relationId,
BlockNumber blkno)
{
int i;
bool result = false;
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
/*
* Locate an unused work item and fill it with the given data.
*/
for (i = 0; i < NUM_WORKITEMS; i++)
{
AutoVacuumWorkItem *workitem = &AutoVacuumShmem->av_workItems[i];
if (workitem->avw_used)
continue;
workitem->avw_used = true;
workitem->avw_active = false;
workitem->avw_type = type;
workitem->avw_database = MyDatabaseId;
workitem->avw_relation = relationId;
workitem->avw_blockNumber = blkno;
result = true;
/* done */
break;
}
LWLockRelease(AutovacuumLock);
return result;
}
/*
* 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 (!IsUnderPostmaster)
{
WorkerInfo worker;
int i;
Assert(!found);
AutoVacuumShmem->av_launcherpid = 0;
dlist_init(&AutoVacuumShmem->av_freeWorkers);
dlist_init(&AutoVacuumShmem->av_runningWorkers);
AutoVacuumShmem->av_startingWorker = NULL;
memset(AutoVacuumShmem->av_workItems, 0,
sizeof(AutoVacuumWorkItem) * NUM_WORKITEMS);
worker = (WorkerInfo) ((char *) AutoVacuumShmem +
MAXALIGN(sizeof(AutoVacuumShmemStruct)));
/* initialize the WorkerInfo free list */
for (i = 0; i < autovacuum_max_workers; i++)
dlist_push_head(&AutoVacuumShmem->av_freeWorkers,
&worker[i].wi_links);
}
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();
}