Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commitedfc03e

Browse files
committed
Fix possibility of self-deadlock in ResolveRecoveryConflictWithBufferPin().
The tests added in9f8a050 failed nearly reliably on FreeBSD in CI, andoccasionally on the buildfarm. That turns out to be caused not by a bug in thetest, but by a longstanding bug in recovery conflict handling.The standby timeout handler, used by ResolveRecoveryConflictWithBufferPin(),executed SendRecoveryConflictWithBufferPin() inside a signal handler. A badidea, because the deadlock timeout handler (or a spurious latch set) couldhave interrupted ProcWaitForSignal(). If unlucky that could cause aself-deadlock on ProcArrayLock, if the deadlock check is inSendRecoveryConflictWithBufferPin()->CancelDBBackends().To fix, set a flag in StandbyTimeoutHandler(), and check the flag inResolveRecoveryConflictWithBufferPin().Subsequently the recovery conflict tests will be backpatched.Discussion:https://postgr.es/m/20220413002626.udl7lll7f3o7nre7@alap3.anarazel.deBackpatch: 10-
1 parent5c8b14a commitedfc03e

File tree

1 file changed

+12
-10
lines changed

1 file changed

+12
-10
lines changed

‎src/backend/storage/ipc/standby.c

Lines changed: 12 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -44,6 +44,7 @@ static HTAB *RecoveryLockLists;
4444

4545
/* Flags set by timeout handlers */
4646
staticvolatilesig_atomic_tgot_standby_deadlock_timeout= false;
47+
staticvolatilesig_atomic_tgot_standby_delay_timeout= false;
4748
staticvolatilesig_atomic_tgot_standby_lock_timeout= false;
4849

4950
staticvoidResolveRecoveryConflictWithVirtualXIDs(VirtualTransactionId*waitlist,
@@ -595,10 +596,15 @@ ResolveRecoveryConflictWithBufferPin(void)
595596
enable_timeouts(timeouts,cnt);
596597
}
597598

598-
/* Wait to be signaled by UnpinBuffer() */
599+
/*
600+
* Wait to be signaled by UnpinBuffer() or for the wait to be interrupted
601+
* by one of the timeouts established above.
602+
*/
599603
ProcWaitForSignal(PG_WAIT_BUFFER_PIN);
600604

601-
if (got_standby_deadlock_timeout)
605+
if (got_standby_delay_timeout)
606+
SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
607+
elseif (got_standby_deadlock_timeout)
602608
{
603609
/*
604610
* Send out a request for hot-standby backends to check themselves for
@@ -624,6 +630,7 @@ ResolveRecoveryConflictWithBufferPin(void)
624630
* individually, but that'd be slower.
625631
*/
626632
disable_all_timeouts(false);
633+
got_standby_delay_timeout= false;
627634
got_standby_deadlock_timeout= false;
628635
}
629636

@@ -683,8 +690,8 @@ CheckRecoveryConflictDeadlock(void)
683690
*/
684691

685692
/*
686-
* StandbyDeadLockHandler() will be called if STANDBY_DEADLOCK_TIMEOUT
687-
*occurs before STANDBY_TIMEOUT.
693+
* StandbyDeadLockHandler() will be called if STANDBY_DEADLOCK_TIMEOUT is
694+
*exceeded.
688695
*/
689696
void
690697
StandbyDeadLockHandler(void)
@@ -694,16 +701,11 @@ StandbyDeadLockHandler(void)
694701

695702
/*
696703
* StandbyTimeoutHandler() will be called if STANDBY_TIMEOUT is exceeded.
697-
* Send out a request to release conflicting buffer pins unconditionally,
698-
* so we can press ahead with applying changes in recovery.
699704
*/
700705
void
701706
StandbyTimeoutHandler(void)
702707
{
703-
/* forget any pending STANDBY_DEADLOCK_TIMEOUT request */
704-
disable_timeout(STANDBY_DEADLOCK_TIMEOUT, false);
705-
706-
SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
708+
got_standby_delay_timeout= true;
707709
}
708710

709711
/*

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp