From 030e4816fe2033ccd9e8488479cd5d2c17a1d6b9 Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Fri, 29 Apr 2022 12:50:10 -0700 Subject: [PATCH vREL_10_STABLE 1/2] Fix possibility of self-deadlock in ResolveRecoveryConflictWithBufferPin(). Author: Reviewed-By: Discussion: https://postgr.es/m/20220413002626.udl7lll7f3o7nre7@alap3.anarazel.de Backpatch: --- src/backend/storage/ipc/standby.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) diff --git a/src/backend/storage/ipc/standby.c b/src/backend/storage/ipc/standby.c index 863cb641007..47cdaead9e6 100644 --- a/src/backend/storage/ipc/standby.c +++ b/src/backend/storage/ipc/standby.c @@ -44,6 +44,7 @@ static HTAB *RecoveryLockLists; /* Flags set by timeout handlers */ static volatile sig_atomic_t got_standby_deadlock_timeout = false; +static volatile sig_atomic_t got_standby_delay_timeout = false; static volatile sig_atomic_t got_standby_lock_timeout = false; static void ResolveRecoveryConflictWithVirtualXIDs(VirtualTransactionId *waitlist, @@ -593,10 +594,15 @@ ResolveRecoveryConflictWithBufferPin(void) enable_timeouts(timeouts, cnt); } - /* Wait to be signaled by UnpinBuffer() */ + /* + * Wait to be signaled by UnpinBuffer() or for the wait to be interrupted + * by one of the timeouts established above. + */ ProcWaitForSignal(PG_WAIT_BUFFER_PIN); - if (got_standby_deadlock_timeout) + if (got_standby_delay_timeout) + SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN); + else if (got_standby_deadlock_timeout) { /* * Send out a request for hot-standby backends to check themselves for @@ -622,6 +628,7 @@ ResolveRecoveryConflictWithBufferPin(void) * individually, but that'd be slower. */ disable_all_timeouts(false); + got_standby_delay_timeout = false; got_standby_deadlock_timeout = false; } @@ -681,8 +688,8 @@ CheckRecoveryConflictDeadlock(void) */ /* - * StandbyDeadLockHandler() will be called if STANDBY_DEADLOCK_TIMEOUT - * occurs before STANDBY_TIMEOUT. + * StandbyDeadLockHandler() will be called if STANDBY_DEADLOCK_TIMEOUT is + * exceeded. */ void StandbyDeadLockHandler(void) @@ -692,16 +699,11 @@ StandbyDeadLockHandler(void) /* * StandbyTimeoutHandler() will be called if STANDBY_TIMEOUT is exceeded. - * Send out a request to release conflicting buffer pins unconditionally, - * so we can press ahead with applying changes in recovery. */ void StandbyTimeoutHandler(void) { - /* forget any pending STANDBY_DEADLOCK_TIMEOUT request */ - disable_timeout(STANDBY_DEADLOCK_TIMEOUT, false); - - SendRecoveryConflictWithBufferPin(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN); + got_standby_delay_timeout = true; } /* -- 2.35.1.677.gabf474a5dd