1 /*-------------------------------------------------------------------------
4 * routines to manage per-process shared memory data structure
6 * Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
11 * src/backend/storage/lmgr/proc.c
13 *-------------------------------------------------------------------------
17 * ProcSleep(), ProcWakeup(),
18 * ProcQueueAlloc() -- create a shm queue for sleeping processes
19 * ProcQueueInit() -- create a queue without allocing memory
21 * Waiting for a lock causes the backend to be put to sleep. Whoever releases
22 * the lock wakes the process up again (and gives it an error code so it knows
23 * whether it was awoken on an error condition).
27 * ProcReleaseLocks -- frees the locks associated with current transaction
29 * ProcKill -- destroys the shared memory state (and locks)
30 * associated with the process.
38 #include "access/transam.h"
39 #include "access/xact.h"
40 #include "miscadmin.h"
41 #include "postmaster/autovacuum.h"
42 #include "replication/syncrep.h"
43 #include "storage/ipc.h"
44 #include "storage/lmgr.h"
45 #include "storage/pmsignal.h"
46 #include "storage/proc.h"
47 #include "storage/procarray.h"
48 #include "storage/procsignal.h"
49 #include "storage/spin.h"
53 int DeadlockTimeout = 1000;
54 int StatementTimeout = 0;
55 bool log_lock_waits = false;
57 /* Pointer to this process's PGPROC struct, if any */
58 PGPROC *MyProc = NULL;
61 * This spinlock protects the freelist of recycled PGPROC structures.
62 * We cannot use an LWLock because the LWLock manager depends on already
63 * having a PGPROC and a wait semaphore! But these structures are touched
64 * relatively infrequently (only at backend startup or shutdown) and not for
65 * very long, so a spinlock is okay.
67 NON_EXEC_STATIC slock_t *ProcStructLock = NULL;
69 /* Pointers to shared-memory structures */
70 NON_EXEC_STATIC PROC_HDR *ProcGlobal = NULL;
71 NON_EXEC_STATIC PGPROC *AuxiliaryProcs = NULL;
73 /* If we are waiting for a lock, this points to the associated LOCALLOCK */
74 static LOCALLOCK *lockAwaited = NULL;
76 /* Mark these volatile because they can be changed by signal handler */
77 static volatile bool standby_timeout_active = false;
78 static volatile bool statement_timeout_active = false;
79 static volatile bool deadlock_timeout_active = false;
80 static volatile DeadLockState deadlock_state = DS_NOT_YET_CHECKED;
81 volatile bool cancel_from_timeout = false;
83 /* timeout_start_time is set when log_lock_waits is true */
84 static TimestampTz timeout_start_time;
86 /* statement_fin_time is valid only if statement_timeout_active is true */
87 static TimestampTz statement_fin_time;
88 static TimestampTz statement_fin_time2; /* valid only in recovery */
91 static void RemoveProcFromArray(int code, Datum arg);
92 static void ProcKill(int code, Datum arg);
93 static void AuxiliaryProcKill(int code, Datum arg);
94 static bool CheckStatementTimeout(void);
95 static bool CheckStandbyTimeout(void);
99 * Report shared-memory space needed by InitProcGlobal.
102 ProcGlobalShmemSize(void)
107 size = add_size(size, sizeof(PROC_HDR));
109 size = add_size(size, mul_size(NUM_AUXILIARY_PROCS, sizeof(PGPROC)));
110 /* MyProcs, including autovacuum workers and launcher */
111 size = add_size(size, mul_size(MaxBackends, sizeof(PGPROC)));
113 size = add_size(size, sizeof(slock_t));
119 * Report number of semaphores needed by InitProcGlobal.
122 ProcGlobalSemas(void)
125 * We need a sema per backend (including autovacuum), plus one for each
128 return MaxBackends + NUM_AUXILIARY_PROCS;
133 * Initialize the global process table during postmaster or standalone
136 * We also create all the per-process semaphores we will need to support
137 * the requested number of backends. We used to allocate semaphores
138 * only when backends were actually started up, but that is bad because
139 * it lets Postgres fail under load --- a lot of Unix systems are
140 * (mis)configured with small limits on the number of semaphores, and
141 * running out when trying to start another backend is a common failure.
142 * So, now we grab enough semaphores to support the desired max number
143 * of backends immediately at initialization --- if the sysadmin has set
144 * MaxConnections or autovacuum_max_workers higher than his kernel will
145 * support, he'll find out sooner rather than later.
147 * Another reason for creating semaphores here is that the semaphore
148 * implementation typically requires us to create semaphores in the
149 * postmaster, not in backends.
151 * Note: this is NOT called by individual backends under a postmaster,
152 * not even in the EXEC_BACKEND case. The ProcGlobal and AuxiliaryProcs
153 * pointers must be propagated specially for EXEC_BACKEND operation.
161 uint32 TotalProcs = MaxBackends + NUM_AUXILIARY_PROCS;
163 /* Create the ProcGlobal shared structure */
164 ProcGlobal = (PROC_HDR *)
165 ShmemInitStruct("Proc Header", sizeof(PROC_HDR), &found);
169 * Initialize the data structures.
171 ProcGlobal->spins_per_delay = DEFAULT_SPINS_PER_DELAY;
172 ProcGlobal->freeProcs = NULL;
173 ProcGlobal->autovacFreeProcs = NULL;
176 * Create and initialize all the PGPROC structures we'll need (except for
177 * those used for 2PC, which are embedded within a GlobalTransactionData
180 * There are three separate consumers of PGPROC structures: (1) normal
181 * backends, (2) autovacuum workers and the autovacuum launcher, and (3)
182 * auxiliary processes. Each PGPROC structure is dedicated to exactly
183 * one of these purposes, and they do not move between groups.
185 procs = (PGPROC *) ShmemAlloc(TotalProcs * sizeof(PGPROC));
188 (errcode(ERRCODE_OUT_OF_MEMORY),
189 errmsg("out of shared memory")));
190 MemSet(procs, 0, TotalProcs * sizeof(PGPROC));
191 for (i = 0; i < TotalProcs; i++)
193 /* Common initialization for all PGPROCs, regardless of type. */
194 PGSemaphoreCreate(&(procs[i].sem));
195 InitSharedLatch(&procs[i].waitLatch);
198 * Newly created PGPROCs for normal backends or for autovacuum must
199 * be queued up on the appropriate free list. Because there can only
200 * ever be a small, fixed number of auxiliary processes, no free
201 * list is used in that case; InitAuxiliaryProcess() instead uses a
204 if (i < MaxConnections)
206 /* PGPROC for normal backend, add to freeProcs list */
207 procs[i].links.next = (SHM_QUEUE *) ProcGlobal->freeProcs;
208 ProcGlobal->freeProcs = &procs[i];
210 else if (i < MaxBackends)
212 /* PGPROC for AV launcher/worker, add to autovacFreeProcs list */
213 procs[i].links.next = (SHM_QUEUE *) ProcGlobal->autovacFreeProcs;
214 ProcGlobal->autovacFreeProcs = &procs[i];
219 * Save a pointer to the block of PGPROC structures reserved for
220 * auxiliary proceses.
222 AuxiliaryProcs = &procs[MaxBackends];
224 /* Create ProcStructLock spinlock, too */
225 ProcStructLock = (slock_t *) ShmemAlloc(sizeof(slock_t));
226 SpinLockInit(ProcStructLock);
230 * InitProcess -- initialize a per-process data structure for this backend
235 /* use volatile pointer to prevent code rearrangement */
236 volatile PROC_HDR *procglobal = ProcGlobal;
240 * ProcGlobal should be set up already (if we are a backend, we inherit
241 * this by fork() or EXEC_BACKEND mechanism from the postmaster).
243 if (procglobal == NULL)
244 elog(PANIC, "proc header uninitialized");
247 elog(ERROR, "you already exist");
250 * Try to get a proc struct from the free list. If this fails, we must be
251 * out of PGPROC structures (not to mention semaphores).
253 * While we are holding the ProcStructLock, also copy the current shared
254 * estimate of spins_per_delay to local storage.
256 SpinLockAcquire(ProcStructLock);
258 set_spins_per_delay(procglobal->spins_per_delay);
260 if (IsAnyAutoVacuumProcess())
261 MyProc = procglobal->autovacFreeProcs;
263 MyProc = procglobal->freeProcs;
267 if (IsAnyAutoVacuumProcess())
268 procglobal->autovacFreeProcs = (PGPROC *) MyProc->links.next;
270 procglobal->freeProcs = (PGPROC *) MyProc->links.next;
271 SpinLockRelease(ProcStructLock);
276 * If we reach here, all the PGPROCs are in use. This is one of the
277 * possible places to detect "too many backends", so give the standard
278 * error message. XXX do we need to give a different failure message
279 * in the autovacuum case?
281 SpinLockRelease(ProcStructLock);
283 (errcode(ERRCODE_TOO_MANY_CONNECTIONS),
284 errmsg("sorry, too many clients already")));
288 * Now that we have a PGPROC, mark ourselves as an active postmaster
289 * child; this is so that the postmaster can detect it if we exit without
290 * cleaning up. (XXX autovac launcher currently doesn't participate in
291 * this; it probably should.)
293 if (IsUnderPostmaster && !IsAutoVacuumLauncherProcess())
294 MarkPostmasterChildActive();
297 * Initialize all fields of MyProc, except for the semaphore which was
298 * prepared for us by InitProcGlobal.
300 SHMQueueElemInit(&(MyProc->links));
301 MyProc->waitStatus = STATUS_OK;
302 MyProc->lxid = InvalidLocalTransactionId;
303 MyProc->xid = InvalidTransactionId;
304 MyProc->xmin = InvalidTransactionId;
305 MyProc->pid = MyProcPid;
306 /* backendId, databaseId and roleId will be filled in later */
307 MyProc->backendId = InvalidBackendId;
308 MyProc->databaseId = InvalidOid;
309 MyProc->roleId = InvalidOid;
310 MyProc->inCommit = false;
311 MyProc->vacuumFlags = 0;
312 /* NB -- autovac launcher intentionally does not set IS_AUTOVACUUM */
313 if (IsAutoVacuumWorkerProcess())
314 MyProc->vacuumFlags |= PROC_IS_AUTOVACUUM;
315 MyProc->lwWaiting = false;
316 MyProc->lwExclusive = false;
317 MyProc->lwWaitLink = NULL;
318 MyProc->waitLock = NULL;
319 MyProc->waitProcLock = NULL;
320 for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
321 SHMQueueInit(&(MyProc->myProcLocks[i]));
322 MyProc->recoveryConflictPending = false;
324 /* Initialise for sync rep */
325 MyProc->waitLSN.xlogid = 0;
326 MyProc->waitLSN.xrecoff = 0;
327 MyProc->syncRepState = SYNC_REP_NOT_WAITING;
328 SHMQueueElemInit(&(MyProc->syncRepLinks));
329 OwnLatch((Latch *) &MyProc->waitLatch);
332 * We might be reusing a semaphore that belonged to a failed process. So
333 * be careful and reinitialize its value here. (This is not strictly
334 * necessary anymore, but seems like a good idea for cleanliness.)
336 PGSemaphoreReset(&MyProc->sem);
339 * Arrange to clean up at backend exit.
341 on_shmem_exit(ProcKill, 0);
344 * Now that we have a PGPROC, we could try to acquire locks, so initialize
345 * the deadlock checker.
347 InitDeadLockChecking();
351 * InitProcessPhase2 -- make MyProc visible in the shared ProcArray.
353 * This is separate from InitProcess because we can't acquire LWLocks until
354 * we've created a PGPROC, but in the EXEC_BACKEND case ProcArrayAdd won't
355 * work until after we've done CreateSharedMemoryAndSemaphores.
358 InitProcessPhase2(void)
360 Assert(MyProc != NULL);
363 * Add our PGPROC to the PGPROC array in shared memory.
365 ProcArrayAdd(MyProc);
368 * Arrange to clean that up at backend exit.
370 on_shmem_exit(SyncRepCleanupAtProcExit, 0);
371 on_shmem_exit(RemoveProcFromArray, 0);
375 * InitAuxiliaryProcess -- create a per-auxiliary-process data structure
377 * This is called by bgwriter and similar processes so that they will have a
378 * MyProc value that's real enough to let them wait for LWLocks. The PGPROC
379 * and sema that are assigned are one of the extra ones created during
382 * Auxiliary processes are presently not expected to wait for real (lockmgr)
383 * locks, so we need not set up the deadlock checker. They are never added
384 * to the ProcArray or the sinval messaging mechanism, either. They also
385 * don't get a VXID assigned, since this is only useful when we actually
386 * hold lockmgr locks.
388 * Startup process however uses locks but never waits for them in the
389 * normal backend sense. Startup process also takes part in sinval messaging
390 * as a sendOnly process, so never reads messages from sinval queue. So
391 * Startup process does have a VXID and does show up in pg_locks.
394 InitAuxiliaryProcess(void)
401 * ProcGlobal should be set up already (if we are a backend, we inherit
402 * this by fork() or EXEC_BACKEND mechanism from the postmaster).
404 if (ProcGlobal == NULL || AuxiliaryProcs == NULL)
405 elog(PANIC, "proc header uninitialized");
408 elog(ERROR, "you already exist");
411 * We use the ProcStructLock to protect assignment and releasing of
412 * AuxiliaryProcs entries.
414 * While we are holding the ProcStructLock, also copy the current shared
415 * estimate of spins_per_delay to local storage.
417 SpinLockAcquire(ProcStructLock);
419 set_spins_per_delay(ProcGlobal->spins_per_delay);
422 * Find a free auxproc ... *big* trouble if there isn't one ...
424 for (proctype = 0; proctype < NUM_AUXILIARY_PROCS; proctype++)
426 auxproc = &AuxiliaryProcs[proctype];
427 if (auxproc->pid == 0)
430 if (proctype >= NUM_AUXILIARY_PROCS)
432 SpinLockRelease(ProcStructLock);
433 elog(FATAL, "all AuxiliaryProcs are in use");
436 /* Mark auxiliary proc as in use by me */
437 /* use volatile pointer to prevent code rearrangement */
438 ((volatile PGPROC *) auxproc)->pid = MyProcPid;
442 SpinLockRelease(ProcStructLock);
445 * Initialize all fields of MyProc, except for the semaphore which was
446 * prepared for us by InitProcGlobal.
448 SHMQueueElemInit(&(MyProc->links));
449 MyProc->waitStatus = STATUS_OK;
450 MyProc->lxid = InvalidLocalTransactionId;
451 MyProc->xid = InvalidTransactionId;
452 MyProc->xmin = InvalidTransactionId;
453 MyProc->backendId = InvalidBackendId;
454 MyProc->databaseId = InvalidOid;
455 MyProc->roleId = InvalidOid;
456 MyProc->inCommit = false;
457 MyProc->vacuumFlags = 0;
458 MyProc->lwWaiting = false;
459 MyProc->lwExclusive = false;
460 MyProc->lwWaitLink = NULL;
461 MyProc->waitLock = NULL;
462 MyProc->waitProcLock = NULL;
463 for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
464 SHMQueueInit(&(MyProc->myProcLocks[i]));
467 * We might be reusing a semaphore that belonged to a failed process. So
468 * be careful and reinitialize its value here. (This is not strictly
469 * necessary anymore, but seems like a good idea for cleanliness.)
471 PGSemaphoreReset(&MyProc->sem);
474 * Arrange to clean up at process exit.
476 on_shmem_exit(AuxiliaryProcKill, Int32GetDatum(proctype));
480 * Record the PID and PGPROC structures for the Startup process, for use in
481 * ProcSendSignal(). See comments there for further explanation.
484 PublishStartupProcessInformation(void)
486 /* use volatile pointer to prevent code rearrangement */
487 volatile PROC_HDR *procglobal = ProcGlobal;
489 SpinLockAcquire(ProcStructLock);
491 procglobal->startupProc = MyProc;
492 procglobal->startupProcPid = MyProcPid;
493 procglobal->startupBufferPinWaitBufId = 0;
495 SpinLockRelease(ProcStructLock);
499 * Used from bufgr to share the value of the buffer that Startup waits on,
500 * or to reset the value to "not waiting" (-1). This allows processing
501 * of recovery conflicts for buffer pins. Set is made before backends look
502 * at this value, so locking not required, especially since the set is
503 * an atomic integer set operation.
506 SetStartupBufferPinWaitBufId(int bufid)
508 /* use volatile pointer to prevent code rearrangement */
509 volatile PROC_HDR *procglobal = ProcGlobal;
511 procglobal->startupBufferPinWaitBufId = bufid;
515 * Used by backends when they receive a request to check for buffer pin waits.
518 GetStartupBufferPinWaitBufId(void)
522 /* use volatile pointer to prevent code rearrangement */
523 volatile PROC_HDR *procglobal = ProcGlobal;
525 bufid = procglobal->startupBufferPinWaitBufId;
531 * Check whether there are at least N free PGPROC objects.
533 * Note: this is designed on the assumption that N will generally be small.
536 HaveNFreeProcs(int n)
540 /* use volatile pointer to prevent code rearrangement */
541 volatile PROC_HDR *procglobal = ProcGlobal;
543 SpinLockAcquire(ProcStructLock);
545 proc = procglobal->freeProcs;
547 while (n > 0 && proc != NULL)
549 proc = (PGPROC *) proc->links.next;
553 SpinLockRelease(ProcStructLock);
559 IsWaitingForLock(void)
561 if (lockAwaited == NULL)
568 * Cancel any pending wait for lock, when aborting a transaction.
570 * (Normally, this would only happen if we accept a cancel/die
571 * interrupt while waiting; but an ereport(ERROR) while waiting is
572 * within the realm of possibility, too.)
577 LWLockId partitionLock;
579 /* Nothing to do if we weren't waiting for a lock */
580 if (lockAwaited == NULL)
583 /* Turn off the deadlock timer, if it's still running (see ProcSleep) */
584 disable_sig_alarm(false);
586 /* Unlink myself from the wait queue, if on it (might not be anymore!) */
587 partitionLock = LockHashPartitionLock(lockAwaited->hashcode);
588 LWLockAcquire(partitionLock, LW_EXCLUSIVE);
590 if (MyProc->links.next != NULL)
592 /* We could not have been granted the lock yet */
593 RemoveFromWaitQueue(MyProc, lockAwaited->hashcode);
598 * Somebody kicked us off the lock queue already. Perhaps they
599 * granted us the lock, or perhaps they detected a deadlock. If they
600 * did grant us the lock, we'd better remember it in our local lock
603 if (MyProc->waitStatus == STATUS_OK)
609 LWLockRelease(partitionLock);
612 * We used to do PGSemaphoreReset() here to ensure that our proc's wait
613 * semaphore is reset to zero. This prevented a leftover wakeup signal
614 * from remaining in the semaphore if someone else had granted us the lock
615 * we wanted before we were able to remove ourselves from the wait-list.
616 * However, now that ProcSleep loops until waitStatus changes, a leftover
617 * wakeup signal isn't harmful, and it seems not worth expending cycles to
618 * get rid of a signal that most likely isn't there.
624 * ProcReleaseLocks() -- release locks associated with current transaction
625 * at main transaction commit or abort
627 * At main transaction commit, we release all locks except session locks.
628 * At main transaction abort, we release all locks including session locks.
630 * At subtransaction commit, we don't release any locks (so this func is not
631 * needed at all); we will defer the releasing to the parent transaction.
632 * At subtransaction abort, we release all locks held by the subtransaction;
633 * this is implemented by retail releasing of the locks under control of
634 * the ResourceOwner mechanism.
637 ProcReleaseLocks(bool isCommit)
641 /* If waiting, get off wait queue (should only be needed after error) */
644 LockReleaseAll(DEFAULT_LOCKMETHOD, !isCommit);
646 /* Release transaction level advisory locks */
647 LockReleaseAll(USER_LOCKMETHOD, false);
652 * RemoveProcFromArray() -- Remove this process from the shared ProcArray.
655 RemoveProcFromArray(int code, Datum arg)
657 Assert(MyProc != NULL);
658 ProcArrayRemove(MyProc, InvalidTransactionId);
662 * ProcKill() -- Destroy the per-proc data structure for
663 * this process. Release any of its held LW locks.
666 ProcKill(int code, Datum arg)
668 /* use volatile pointer to prevent code rearrangement */
669 volatile PROC_HDR *procglobal = ProcGlobal;
671 Assert(MyProc != NULL);
674 * Release any LW locks I am holding. There really shouldn't be any, but
675 * it's cheap to check again before we cut the knees off the LWLock
676 * facility by releasing our PGPROC ...
680 SpinLockAcquire(ProcStructLock);
682 /* Return PGPROC structure (and semaphore) to appropriate freelist */
683 if (IsAnyAutoVacuumProcess())
685 MyProc->links.next = (SHM_QUEUE *) procglobal->autovacFreeProcs;
686 procglobal->autovacFreeProcs = MyProc;
690 MyProc->links.next = (SHM_QUEUE *) procglobal->freeProcs;
691 procglobal->freeProcs = MyProc;
694 /* PGPROC struct isn't mine anymore */
697 /* Update shared estimate of spins_per_delay */
698 procglobal->spins_per_delay = update_spins_per_delay(procglobal->spins_per_delay);
700 SpinLockRelease(ProcStructLock);
703 * This process is no longer present in shared memory in any meaningful
704 * way, so tell the postmaster we've cleaned up acceptably well. (XXX
705 * autovac launcher should be included here someday)
707 if (IsUnderPostmaster && !IsAutoVacuumLauncherProcess())
708 MarkPostmasterChildInactive();
710 /* wake autovac launcher if needed -- see comments in FreeWorkerInfo */
711 if (AutovacuumLauncherPid != 0)
712 kill(AutovacuumLauncherPid, SIGUSR2);
716 * AuxiliaryProcKill() -- Cut-down version of ProcKill for auxiliary
717 * processes (bgwriter, etc). The PGPROC and sema are not released, only
718 * marked as not-in-use.
721 AuxiliaryProcKill(int code, Datum arg)
723 int proctype = DatumGetInt32(arg);
726 Assert(proctype >= 0 && proctype < NUM_AUXILIARY_PROCS);
728 auxproc = &AuxiliaryProcs[proctype];
730 Assert(MyProc == auxproc);
732 /* Release any LW locks I am holding (see notes above) */
735 SpinLockAcquire(ProcStructLock);
737 /* Mark auxiliary proc no longer in use */
740 /* PGPROC struct isn't mine anymore */
743 /* Update shared estimate of spins_per_delay */
744 ProcGlobal->spins_per_delay = update_spins_per_delay(ProcGlobal->spins_per_delay);
746 SpinLockRelease(ProcStructLock);
751 * ProcQueue package: routines for putting processes to sleep
756 * ProcQueueAlloc -- alloc/attach to a shared memory process queue
758 * Returns: a pointer to the queue
759 * Side Effects: Initializes the queue if it wasn't there before
763 ProcQueueAlloc(const char *name)
768 queue = (PROC_QUEUE *)
769 ShmemInitStruct(name, sizeof(PROC_QUEUE), &found);
772 ProcQueueInit(queue);
779 * ProcQueueInit -- initialize a shared memory process queue
782 ProcQueueInit(PROC_QUEUE *queue)
784 SHMQueueInit(&(queue->links));
790 * ProcSleep -- put a process to sleep on the specified lock
792 * Caller must have set MyProc->heldLocks to reflect locks already held
793 * on the lockable object by this process (under all XIDs).
795 * The lock table's partition lock must be held at entry, and will be held
798 * Result: STATUS_OK if we acquired the lock, STATUS_ERROR if not (deadlock).
800 * ASSUME: that no one will fiddle with the queue until after
801 * we release the partition lock.
803 * NOTES: The process queue is now a priority queue for locking.
805 * P() on the semaphore should put us to sleep. The process
806 * semaphore is normally zero, so when we try to acquire it, we sleep.
809 ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
811 LOCKMODE lockmode = locallock->tag.mode;
812 LOCK *lock = locallock->lock;
813 PROCLOCK *proclock = locallock->proclock;
814 uint32 hashcode = locallock->hashcode;
815 LWLockId partitionLock = LockHashPartitionLock(hashcode);
816 PROC_QUEUE *waitQueue = &(lock->waitProcs);
817 LOCKMASK myHeldLocks = MyProc->heldLocks;
818 bool early_deadlock = false;
819 bool allow_autovacuum_cancel = true;
825 * Determine where to add myself in the wait queue.
827 * Normally I should go at the end of the queue. However, if I already
828 * hold locks that conflict with the request of any previous waiter, put
829 * myself in the queue just in front of the first such waiter. This is not
830 * a necessary step, since deadlock detection would move me to before that
831 * waiter anyway; but it's relatively cheap to detect such a conflict
832 * immediately, and avoid delaying till deadlock timeout.
834 * Special case: if I find I should go in front of some waiter, check to
835 * see if I conflict with already-held locks or the requests before that
836 * waiter. If not, then just grant myself the requested lock immediately.
837 * This is the same as the test for immediate grant in LockAcquire, except
838 * we are only considering the part of the wait queue before my insertion
841 if (myHeldLocks != 0)
843 LOCKMASK aheadRequests = 0;
845 proc = (PGPROC *) waitQueue->links.next;
846 for (i = 0; i < waitQueue->size; i++)
848 /* Must he wait for me? */
849 if (lockMethodTable->conflictTab[proc->waitLockMode] & myHeldLocks)
851 /* Must I wait for him ? */
852 if (lockMethodTable->conflictTab[lockmode] & proc->heldLocks)
855 * Yes, so we have a deadlock. Easiest way to clean up
856 * correctly is to call RemoveFromWaitQueue(), but we
857 * can't do that until we are *on* the wait queue. So, set
858 * a flag to check below, and break out of loop. Also,
859 * record deadlock info for later message.
861 RememberSimpleDeadLock(MyProc, lockmode, lock, proc);
862 early_deadlock = true;
865 /* I must go before this waiter. Check special case. */
866 if ((lockMethodTable->conflictTab[lockmode] & aheadRequests) == 0 &&
867 LockCheckConflicts(lockMethodTable,
871 MyProc) == STATUS_OK)
873 /* Skip the wait and just grant myself the lock. */
874 GrantLock(lock, proclock, lockmode);
878 /* Break out of loop to put myself before him */
881 /* Nope, so advance to next waiter */
882 aheadRequests |= LOCKBIT_ON(proc->waitLockMode);
883 proc = (PGPROC *) proc->links.next;
887 * If we fall out of loop normally, proc points to waitQueue head, so
888 * we will insert at tail of queue as desired.
893 /* I hold no locks, so I can't push in front of anyone. */
894 proc = (PGPROC *) &(waitQueue->links);
898 * Insert self into queue, ahead of the given proc (or at tail of queue).
900 SHMQueueInsertBefore(&(proc->links), &(MyProc->links));
903 lock->waitMask |= LOCKBIT_ON(lockmode);
905 /* Set up wait information in PGPROC object, too */
906 MyProc->waitLock = lock;
907 MyProc->waitProcLock = proclock;
908 MyProc->waitLockMode = lockmode;
910 MyProc->waitStatus = STATUS_WAITING;
913 * If we detected deadlock, give up without waiting. This must agree with
914 * CheckDeadLock's recovery code, except that we shouldn't release the
915 * semaphore since we haven't tried to lock it yet.
919 RemoveFromWaitQueue(MyProc, hashcode);
923 /* mark that we are waiting for a lock */
924 lockAwaited = locallock;
927 * Release the lock table's partition lock.
929 * NOTE: this may also cause us to exit critical-section state, possibly
930 * allowing a cancel/die interrupt to be accepted. This is OK because we
931 * have recorded the fact that we are waiting for a lock, and so
932 * LockWaitCancel will clean up if cancel/die happens.
934 LWLockRelease(partitionLock);
936 /* Reset deadlock_state before enabling the signal handler */
937 deadlock_state = DS_NOT_YET_CHECKED;
940 * Set timer so we can wake up after awhile and check for a deadlock. If a
941 * deadlock is detected, the handler releases the process's semaphore and
942 * sets MyProc->waitStatus = STATUS_ERROR, allowing us to know that we
943 * must report failure rather than success.
945 * By delaying the check until we've waited for a bit, we can avoid
946 * running the rather expensive deadlock-check code in most cases.
948 if (!enable_sig_alarm(DeadlockTimeout, false))
949 elog(FATAL, "could not set timer for process wakeup");
952 * If someone wakes us between LWLockRelease and PGSemaphoreLock,
953 * PGSemaphoreLock will not block. The wakeup is "saved" by the semaphore
954 * implementation. While this is normally good, there are cases where a
955 * saved wakeup might be leftover from a previous operation (for example,
956 * we aborted ProcWaitForSignal just before someone did ProcSendSignal).
957 * So, loop to wait again if the waitStatus shows we haven't been granted
958 * nor denied the lock yet.
960 * We pass interruptOK = true, which eliminates a window in which
961 * cancel/die interrupts would be held off undesirably. This is a promise
962 * that we don't mind losing control to a cancel/die interrupt here. We
963 * don't, because we have no shared-state-change work to do after being
964 * granted the lock (the grantor did it all). We do have to worry about
965 * updating the locallock table, but if we lose control to an error,
966 * LockWaitCancel will fix that up.
970 PGSemaphoreLock(&MyProc->sem, true);
973 * waitStatus could change from STATUS_WAITING to something else
974 * asynchronously. Read it just once per loop to prevent surprising
975 * behavior (such as missing log messages).
977 myWaitStatus = MyProc->waitStatus;
980 * If we are not deadlocked, but are waiting on an autovacuum-induced
981 * task, send a signal to interrupt it.
983 if (deadlock_state == DS_BLOCKED_BY_AUTOVACUUM && allow_autovacuum_cancel)
985 PGPROC *autovac = GetBlockingAutoVacuumPgproc();
987 LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
990 * Only do it if the worker is not working to protect against Xid
993 if ((autovac != NULL) &&
994 (autovac->vacuumFlags & PROC_IS_AUTOVACUUM) &&
995 !(autovac->vacuumFlags & PROC_VACUUM_FOR_WRAPAROUND))
997 int pid = autovac->pid;
999 elog(DEBUG2, "sending cancel to blocking autovacuum pid = %d",
1002 /* don't hold the lock across the kill() syscall */
1003 LWLockRelease(ProcArrayLock);
1005 /* send the autovacuum worker Back to Old Kent Road */
1006 if (kill(pid, SIGINT) < 0)
1008 /* Just a warning to allow multiple callers */
1010 (errmsg("could not send signal to process %d: %m",
1015 LWLockRelease(ProcArrayLock);
1017 /* prevent signal from being resent more than once */
1018 allow_autovacuum_cancel = false;
1022 * If awoken after the deadlock check interrupt has run, and
1023 * log_lock_waits is on, then report about the wait.
1025 if (log_lock_waits && deadlock_state != DS_NOT_YET_CHECKED)
1028 const char *modename;
1033 initStringInfo(&buf);
1034 DescribeLockTag(&buf, &locallock->tag.lock);
1035 modename = GetLockmodeName(locallock->tag.lock.locktag_lockmethodid,
1037 TimestampDifference(timeout_start_time, GetCurrentTimestamp(),
1039 msecs = secs * 1000 + usecs / 1000;
1040 usecs = usecs % 1000;
1042 if (deadlock_state == DS_SOFT_DEADLOCK)
1044 (errmsg("process %d avoided deadlock for %s on %s by rearranging queue order after %ld.%03d ms",
1045 MyProcPid, modename, buf.data, msecs, usecs)));
1046 else if (deadlock_state == DS_HARD_DEADLOCK)
1049 * This message is a bit redundant with the error that will be
1050 * reported subsequently, but in some cases the error report
1051 * might not make it to the log (eg, if it's caught by an
1052 * exception handler), and we want to ensure all long-wait
1053 * events get logged.
1056 (errmsg("process %d detected deadlock while waiting for %s on %s after %ld.%03d ms",
1057 MyProcPid, modename, buf.data, msecs, usecs)));
1060 if (myWaitStatus == STATUS_WAITING)
1062 (errmsg("process %d still waiting for %s on %s after %ld.%03d ms",
1063 MyProcPid, modename, buf.data, msecs, usecs)));
1064 else if (myWaitStatus == STATUS_OK)
1066 (errmsg("process %d acquired %s on %s after %ld.%03d ms",
1067 MyProcPid, modename, buf.data, msecs, usecs)));
1070 Assert(myWaitStatus == STATUS_ERROR);
1073 * Currently, the deadlock checker always kicks its own
1074 * process, which means that we'll only see STATUS_ERROR when
1075 * deadlock_state == DS_HARD_DEADLOCK, and there's no need to
1076 * print redundant messages. But for completeness and
1077 * future-proofing, print a message if it looks like someone
1078 * else kicked us off the lock.
1080 if (deadlock_state != DS_HARD_DEADLOCK)
1082 (errmsg("process %d failed to acquire %s on %s after %ld.%03d ms",
1083 MyProcPid, modename, buf.data, msecs, usecs)));
1087 * At this point we might still need to wait for the lock. Reset
1088 * state so we don't print the above messages again.
1090 deadlock_state = DS_NO_DEADLOCK;
1094 } while (myWaitStatus == STATUS_WAITING);
1097 * Disable the timer, if it's still running
1099 if (!disable_sig_alarm(false))
1100 elog(FATAL, "could not disable timer for process wakeup");
1103 * Re-acquire the lock table's partition lock. We have to do this to hold
1104 * off cancel/die interrupts before we can mess with lockAwaited (else we
1105 * might have a missed or duplicated locallock update).
1107 LWLockAcquire(partitionLock, LW_EXCLUSIVE);
1110 * We no longer want LockWaitCancel to do anything.
1115 * If we got the lock, be sure to remember it in the locallock table.
1117 if (MyProc->waitStatus == STATUS_OK)
1121 * We don't have to do anything else, because the awaker did all the
1122 * necessary update of the lock table and MyProc.
1124 return MyProc->waitStatus;
1129 * ProcWakeup -- wake up a process by releasing its private semaphore.
1131 * Also remove the process from the wait queue and set its links invalid.
1132 * RETURN: the next process in the wait queue.
1134 * The appropriate lock partition lock must be held by caller.
1136 * XXX: presently, this code is only used for the "success" case, and only
1137 * works correctly for that case. To clean up in failure case, would need
1138 * to twiddle the lock's request counts too --- see RemoveFromWaitQueue.
1139 * Hence, in practice the waitStatus parameter must be STATUS_OK.
1142 ProcWakeup(PGPROC *proc, int waitStatus)
1146 /* Proc should be sleeping ... */
1147 if (proc->links.prev == NULL ||
1148 proc->links.next == NULL)
1150 Assert(proc->waitStatus == STATUS_WAITING);
1152 /* Save next process before we zap the list link */
1153 retProc = (PGPROC *) proc->links.next;
1155 /* Remove process from wait queue */
1156 SHMQueueDelete(&(proc->links));
1157 (proc->waitLock->waitProcs.size)--;
1159 /* Clean up process' state and pass it the ok/fail signal */
1160 proc->waitLock = NULL;
1161 proc->waitProcLock = NULL;
1162 proc->waitStatus = waitStatus;
1165 PGSemaphoreUnlock(&proc->sem);
1171 * ProcLockWakeup -- routine for waking up processes when a lock is
1172 * released (or a prior waiter is aborted). Scan all waiters
1173 * for lock, waken any that are no longer blocked.
1175 * The appropriate lock partition lock must be held by caller.
1178 ProcLockWakeup(LockMethod lockMethodTable, LOCK *lock)
1180 PROC_QUEUE *waitQueue = &(lock->waitProcs);
1181 int queue_size = waitQueue->size;
1183 LOCKMASK aheadRequests = 0;
1185 Assert(queue_size >= 0);
1187 if (queue_size == 0)
1190 proc = (PGPROC *) waitQueue->links.next;
1192 while (queue_size-- > 0)
1194 LOCKMODE lockmode = proc->waitLockMode;
1197 * Waken if (a) doesn't conflict with requests of earlier waiters, and
1198 * (b) doesn't conflict with already-held locks.
1200 if ((lockMethodTable->conflictTab[lockmode] & aheadRequests) == 0 &&
1201 LockCheckConflicts(lockMethodTable,
1208 GrantLock(lock, proc->waitProcLock, lockmode);
1209 proc = ProcWakeup(proc, STATUS_OK);
1212 * ProcWakeup removes proc from the lock's waiting process queue
1213 * and returns the next proc in chain; don't use proc's next-link,
1214 * because it's been cleared.
1220 * Cannot wake this guy. Remember his request for later checks.
1222 aheadRequests |= LOCKBIT_ON(lockmode);
1223 proc = (PGPROC *) proc->links.next;
1227 Assert(waitQueue->size >= 0);
1233 * We only get to this routine if we got SIGALRM after DeadlockTimeout
1234 * while waiting for a lock to be released by some other process. Look
1235 * to see if there's a deadlock; if not, just return and continue waiting.
1236 * (But signal ProcSleep to log a message, if log_lock_waits is true.)
1237 * If we have a real deadlock, remove ourselves from the lock's wait queue
1238 * and signal an error to ProcSleep.
1240 * NB: this is run inside a signal handler, so be very wary about what is done
1241 * here or in called routines.
1249 * Acquire exclusive lock on the entire shared lock data structures. Must
1250 * grab LWLocks in partition-number order to avoid LWLock deadlock.
1252 * Note that the deadlock check interrupt had better not be enabled
1253 * anywhere that this process itself holds lock partition locks, else this
1254 * will wait forever. Also note that LWLockAcquire creates a critical
1255 * section, so that this routine cannot be interrupted by cancel/die
1258 for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
1259 LWLockAcquire(FirstLockMgrLock + i, LW_EXCLUSIVE);
1262 * Check to see if we've been awoken by anyone in the interim.
1264 * If we have, we can return and resume our transaction -- happy day.
1265 * Before we are awoken the process releasing the lock grants it to us so
1266 * we know that we don't have to wait anymore.
1268 * We check by looking to see if we've been unlinked from the wait queue.
1269 * This is quicker than checking our semaphore's state, since no kernel
1270 * call is needed, and it is safe because we hold the lock partition lock.
1272 if (MyProc->links.prev == NULL ||
1273 MyProc->links.next == NULL)
1277 if (Debug_deadlocks)
1281 /* Run the deadlock check, and set deadlock_state for use by ProcSleep */
1282 deadlock_state = DeadLockCheck(MyProc);
1284 if (deadlock_state == DS_HARD_DEADLOCK)
1287 * Oops. We have a deadlock.
1289 * Get this process out of wait state. (Note: we could do this more
1290 * efficiently by relying on lockAwaited, but use this coding to
1291 * preserve the flexibility to kill some other transaction than the
1292 * one detecting the deadlock.)
1294 * RemoveFromWaitQueue sets MyProc->waitStatus to STATUS_ERROR, so
1295 * ProcSleep will report an error after we return from the signal
1298 Assert(MyProc->waitLock != NULL);
1299 RemoveFromWaitQueue(MyProc, LockTagHashCode(&(MyProc->waitLock->tag)));
1302 * Unlock my semaphore so that the interrupted ProcSleep() call can
1305 PGSemaphoreUnlock(&MyProc->sem);
1308 * We're done here. Transaction abort caused by the error that
1309 * ProcSleep will raise will cause any other locks we hold to be
1310 * released, thus allowing other processes to wake up; we don't need
1311 * to do that here. NOTE: an exception is that releasing locks we
1312 * hold doesn't consider the possibility of waiters that were blocked
1313 * behind us on the lock we just failed to get, and might now be
1314 * wakable because we're not in front of them anymore. However,
1315 * RemoveFromWaitQueue took care of waking up any such processes.
1318 else if (log_lock_waits || deadlock_state == DS_BLOCKED_BY_AUTOVACUUM)
1321 * Unlock my semaphore so that the interrupted ProcSleep() call can
1322 * print the log message (we daren't do it here because we are inside
1323 * a signal handler). It will then sleep again until someone releases
1326 * If blocked by autovacuum, this wakeup will enable ProcSleep to send
1327 * the cancelling signal to the autovacuum worker.
1329 PGSemaphoreUnlock(&MyProc->sem);
1333 * And release locks. We do this in reverse order for two reasons: (1)
1334 * Anyone else who needs more than one of the locks will be trying to lock
1335 * them in increasing order; we don't want to release the other process
1336 * until it can get all the locks it needs. (2) This avoids O(N^2)
1337 * behavior inside LWLockRelease.
1340 for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
1341 LWLockRelease(FirstLockMgrLock + i);
1346 * ProcWaitForSignal - wait for a signal from another backend.
1348 * This can share the semaphore normally used for waiting for locks,
1349 * since a backend could never be waiting for a lock and a signal at
1350 * the same time. As with locks, it's OK if the signal arrives just
1351 * before we actually reach the waiting state. Also as with locks,
1352 * it's necessary that the caller be robust against bogus wakeups:
1353 * always check that the desired state has occurred, and wait again
1354 * if not. This copes with possible "leftover" wakeups.
1357 ProcWaitForSignal(void)
1359 PGSemaphoreLock(&MyProc->sem, true);
1363 * ProcSendSignal - send a signal to a backend identified by PID
1366 ProcSendSignal(int pid)
1368 PGPROC *proc = NULL;
1370 if (RecoveryInProgress())
1372 /* use volatile pointer to prevent code rearrangement */
1373 volatile PROC_HDR *procglobal = ProcGlobal;
1375 SpinLockAcquire(ProcStructLock);
1378 * Check to see whether it is the Startup process we wish to signal.
1379 * This call is made by the buffer manager when it wishes to wake up a
1380 * process that has been waiting for a pin in so it can obtain a
1381 * cleanup lock using LockBufferForCleanup(). Startup is not a normal
1382 * backend, so BackendPidGetProc() will not return any pid at all. So
1383 * we remember the information for this special case.
1385 if (pid == procglobal->startupProcPid)
1386 proc = procglobal->startupProc;
1388 SpinLockRelease(ProcStructLock);
1392 proc = BackendPidGetProc(pid);
1395 PGSemaphoreUnlock(&proc->sem);
1399 /*****************************************************************************
1400 * SIGALRM interrupt support
1402 * Maybe these should be in pqsignal.c?
1403 *****************************************************************************/
1406 * Enable the SIGALRM interrupt to fire after the specified delay
1408 * Delay is given in milliseconds. Caller should be sure a SIGALRM
1409 * signal handler is installed before this is called.
1411 * This code properly handles nesting of deadlock timeout alarms within
1412 * statement timeout alarms.
1414 * Returns TRUE if okay, FALSE on failure.
1417 enable_sig_alarm(int delayms, bool is_statement_timeout)
1419 TimestampTz fin_time;
1420 struct itimerval timeval;
1422 if (is_statement_timeout)
1425 * Begin statement-level timeout
1427 * Note that we compute statement_fin_time with reference to the
1428 * statement_timestamp, but apply the specified delay without any
1429 * correction; that is, we ignore whatever time has elapsed since
1430 * statement_timestamp was set. In the normal case only a small
1431 * interval will have elapsed and so this doesn't matter, but there
1432 * are corner cases (involving multi-statement query strings with
1433 * embedded COMMIT or ROLLBACK) where we might re-initialize the
1434 * statement timeout long after initial receipt of the message. In
1435 * such cases the enforcement of the statement timeout will be a bit
1436 * inconsistent. This annoyance is judged not worth the cost of
1437 * performing an additional gettimeofday() here.
1439 Assert(!deadlock_timeout_active);
1440 fin_time = GetCurrentStatementStartTimestamp();
1441 fin_time = TimestampTzPlusMilliseconds(fin_time, delayms);
1442 statement_fin_time = fin_time;
1443 cancel_from_timeout = false;
1444 statement_timeout_active = true;
1446 else if (statement_timeout_active)
1449 * Begin deadlock timeout with statement-level timeout active
1451 * Here, we want to interrupt at the closer of the two timeout times.
1452 * If fin_time >= statement_fin_time then we need not touch the
1453 * existing timer setting; else set up to interrupt at the deadlock
1456 * NOTE: in this case it is possible that this routine will be
1457 * interrupted by the previously-set timer alarm. This is okay
1458 * because the signal handler will do only what it should do according
1459 * to the state variables. The deadlock checker may get run earlier
1460 * than normal, but that does no harm.
1462 timeout_start_time = GetCurrentTimestamp();
1463 fin_time = TimestampTzPlusMilliseconds(timeout_start_time, delayms);
1464 deadlock_timeout_active = true;
1465 if (fin_time >= statement_fin_time)
1470 /* Begin deadlock timeout with no statement-level timeout */
1471 deadlock_timeout_active = true;
1472 /* GetCurrentTimestamp can be expensive, so only do it if we must */
1474 timeout_start_time = GetCurrentTimestamp();
1477 /* If we reach here, okay to set the timer interrupt */
1478 MemSet(&timeval, 0, sizeof(struct itimerval));
1479 timeval.it_value.tv_sec = delayms / 1000;
1480 timeval.it_value.tv_usec = (delayms % 1000) * 1000;
1481 if (setitimer(ITIMER_REAL, &timeval, NULL))
1487 * Cancel the SIGALRM timer, either for a deadlock timeout or a statement
1488 * timeout. If a deadlock timeout is canceled, any active statement timeout
1491 * Returns TRUE if okay, FALSE on failure.
1494 disable_sig_alarm(bool is_statement_timeout)
1497 * Always disable the interrupt if it is active; this avoids being
1498 * interrupted by the signal handler and thereby possibly getting
1501 * We will re-enable the interrupt if necessary in CheckStatementTimeout.
1503 if (statement_timeout_active || deadlock_timeout_active)
1505 struct itimerval timeval;
1507 MemSet(&timeval, 0, sizeof(struct itimerval));
1508 if (setitimer(ITIMER_REAL, &timeval, NULL))
1510 statement_timeout_active = false;
1511 cancel_from_timeout = false;
1512 deadlock_timeout_active = false;
1517 /* Always cancel deadlock timeout, in case this is error cleanup */
1518 deadlock_timeout_active = false;
1520 /* Cancel or reschedule statement timeout */
1521 if (is_statement_timeout)
1523 statement_timeout_active = false;
1524 cancel_from_timeout = false;
1526 else if (statement_timeout_active)
1528 if (!CheckStatementTimeout())
1536 * Check for statement timeout. If the timeout time has come,
1537 * trigger a query-cancel interrupt; if not, reschedule the SIGALRM
1538 * interrupt to occur at the right time.
1540 * Returns true if okay, false if failed to set the interrupt.
1543 CheckStatementTimeout(void)
1547 if (!statement_timeout_active)
1548 return true; /* do nothing if not active */
1550 now = GetCurrentTimestamp();
1552 if (now >= statement_fin_time)
1555 statement_timeout_active = false;
1556 cancel_from_timeout = true;
1558 /* try to signal whole process group */
1559 kill(-MyProcPid, SIGINT);
1561 kill(MyProcPid, SIGINT);
1565 /* Not time yet, so (re)schedule the interrupt */
1568 struct itimerval timeval;
1570 TimestampDifference(now, statement_fin_time,
1574 * It's possible that the difference is less than a microsecond;
1575 * ensure we don't cancel, rather than set, the interrupt.
1577 if (secs == 0 && usecs == 0)
1579 MemSet(&timeval, 0, sizeof(struct itimerval));
1580 timeval.it_value.tv_sec = secs;
1581 timeval.it_value.tv_usec = usecs;
1582 if (setitimer(ITIMER_REAL, &timeval, NULL))
1591 * Signal handler for SIGALRM for normal user backends
1593 * Process deadlock check and/or statement timeout check, as needed.
1594 * To avoid various edge cases, we must be careful to do nothing
1595 * when there is nothing to be done. We also need to be able to
1596 * reschedule the timer interrupt if called before end of statement.
1599 handle_sig_alarm(SIGNAL_ARGS)
1601 int save_errno = errno;
1603 if (deadlock_timeout_active)
1605 deadlock_timeout_active = false;
1609 if (statement_timeout_active)
1610 (void) CheckStatementTimeout();
1616 * Signal handler for SIGALRM in Startup process
1618 * To avoid various edge cases, we must be careful to do nothing
1619 * when there is nothing to be done. We also need to be able to
1620 * reschedule the timer interrupt if called before end of statement.
1622 * We set either deadlock_timeout_active or statement_timeout_active
1623 * or both. Interrupts are enabled if standby_timeout_active.
1626 enable_standby_sig_alarm(TimestampTz now, TimestampTz fin_time, bool deadlock_only)
1628 TimestampTz deadlock_time = TimestampTzPlusMilliseconds(now,
1634 * Wake up at deadlock_time only, then wait forever
1636 statement_fin_time = deadlock_time;
1637 deadlock_timeout_active = true;
1638 statement_timeout_active = false;
1640 else if (fin_time > deadlock_time)
1643 * Wake up at deadlock_time, then again at fin_time
1645 statement_fin_time = deadlock_time;
1646 statement_fin_time2 = fin_time;
1647 deadlock_timeout_active = true;
1648 statement_timeout_active = true;
1653 * Wake only at fin_time because its fairly soon
1655 statement_fin_time = fin_time;
1656 deadlock_timeout_active = false;
1657 statement_timeout_active = true;
1660 if (deadlock_timeout_active || statement_timeout_active)
1664 struct itimerval timeval;
1666 TimestampDifference(now, statement_fin_time,
1668 if (secs == 0 && usecs == 0)
1670 MemSet(&timeval, 0, sizeof(struct itimerval));
1671 timeval.it_value.tv_sec = secs;
1672 timeval.it_value.tv_usec = usecs;
1673 if (setitimer(ITIMER_REAL, &timeval, NULL))
1675 standby_timeout_active = true;
1682 disable_standby_sig_alarm(void)
1685 * Always disable the interrupt if it is active; this avoids being
1686 * interrupted by the signal handler and thereby possibly getting
1689 * We will re-enable the interrupt if necessary in CheckStandbyTimeout.
1691 if (standby_timeout_active)
1693 struct itimerval timeval;
1695 MemSet(&timeval, 0, sizeof(struct itimerval));
1696 if (setitimer(ITIMER_REAL, &timeval, NULL))
1698 standby_timeout_active = false;
1703 standby_timeout_active = false;
1709 * CheckStandbyTimeout() runs unconditionally in the Startup process
1710 * SIGALRM handler. Timers will only be set when InHotStandby.
1711 * We simply ignore any signals unless the timer has been set.
1714 CheckStandbyTimeout(void)
1717 bool reschedule = false;
1719 standby_timeout_active = false;
1721 now = GetCurrentTimestamp();
1724 * Reschedule the timer if its not time to wake yet, or if we have both
1725 * timers set and the first one has just been reached.
1727 if (now >= statement_fin_time)
1729 if (deadlock_timeout_active)
1732 * We're still waiting when we reach deadlock timeout, so send out
1733 * a request to have other backends check themselves for deadlock.
1734 * Then continue waiting until statement_fin_time, if that's set.
1736 SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK);
1737 deadlock_timeout_active = false;
1740 * Begin second waiting period if required.
1742 if (statement_timeout_active)
1745 statement_fin_time = statement_fin_time2;
1751 * We've now reached statement_fin_time, so ask all conflicts to
1752 * leave, so we can press ahead with applying changes in recovery.
1754 SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
1764 struct itimerval timeval;
1766 TimestampDifference(now, statement_fin_time,
1768 if (secs == 0 && usecs == 0)
1770 MemSet(&timeval, 0, sizeof(struct itimerval));
1771 timeval.it_value.tv_sec = secs;
1772 timeval.it_value.tv_usec = usecs;
1773 if (setitimer(ITIMER_REAL, &timeval, NULL))
1775 standby_timeout_active = true;
1782 handle_standby_sig_alarm(SIGNAL_ARGS)
1784 int save_errno = errno;
1786 if (standby_timeout_active)
1787 (void) CheckStandbyTimeout();