From f03e945f140d52a9e4910ab0d66a01d659c43c9f Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Tue, 2 Mar 2021 11:47:39 +1300 Subject: [PATCH v6 2/3] Add condition variable for recovery pause/resume. This gives us a fast reaction time when recovery is resumed or the postmaster exits. Unfortunately we still need to wake up every second to perform more expensive checks during the recovery pause loop. Reviewed-by: Heikki Linnakangas Reviewed-by: Fujii Masao Reviewed-by: Michael Paquier Discussion: https://postgr.es/m/CA%2BhUKGK1607VmtrDUHQXrsooU%3Dap4g4R2yaoByWOOA3m8xevUQ%40mail.gmail.com --- src/backend/access/transam/xlog.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 377afb8732..17240e9b8f 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -723,6 +723,7 @@ typedef struct XLogCtlData TimestampTz currentChunkStartTime; /* Are we requested to pause recovery? */ bool recoveryPause; + ConditionVariable recoveryPauseChanged; /* * lastFpwDisableRecPtr points to the start of the last replayed @@ -5204,6 +5205,7 @@ XLOGShmemInit(void) SpinLockInit(&XLogCtl->info_lck); SpinLockInit(&XLogCtl->ulsn_lck); InitSharedLatch(&XLogCtl->recoveryWakeupLatch); + ConditionVariableInit(&XLogCtl->recoveryPauseChanged); } /* @@ -6016,10 +6018,6 @@ recoveryStopsAfter(XLogReaderState *record) * endOfRecovery is true if the recovery target is reached and * the paused state starts at the end of recovery because of * recovery_target_action=pause, and false otherwise. - * - * XXX Could also be done with shared latch, avoiding the pg_usleep loop. - * Probably not worth the trouble though. This state shouldn't be one that - * anyone cares about server power consumption in. */ static void recoveryPausesHere(bool endOfRecovery) @@ -6041,15 +6039,22 @@ recoveryPausesHere(bool endOfRecovery) (errmsg("recovery has paused"), errhint("Execute pg_wal_replay_resume() to continue."))); + ConditionVariablePrepareToSleep(&XLogCtl->recoveryPauseChanged); while (RecoveryIsPaused()) { HandleStartupProcInterrupts(); if (CheckForStandbyTrigger()) - return; - pgstat_report_wait_start(WAIT_EVENT_RECOVERY_PAUSE); - pg_usleep(1000000L); /* 1000 ms */ - pgstat_report_wait_end(); + break; + + /* + * We wait on a condition variable that will wake us as soon as the + * pause ends, but we use a timeout so we can check the above exit + * condition periodically too. + */ + ConditionVariableTimedSleep(&XLogCtl->recoveryPauseChanged, 1000, + WAIT_EVENT_RECOVERY_PAUSE); } + ConditionVariableCancelSleep(); } bool @@ -6070,6 +6075,8 @@ SetRecoveryPause(bool recoveryPause) SpinLockAcquire(&XLogCtl->info_lck); XLogCtl->recoveryPause = recoveryPause; SpinLockRelease(&XLogCtl->info_lck); + + ConditionVariableBroadcast(&XLogCtl->recoveryPauseChanged); } /* -- 2.30.1