From a499a683c6f4a93bdc58ea05cecb531d2b917cf7 Mon Sep 17 00:00:00 2001 From: Martijn van Oosterhout Date: Fri, 2 Aug 2019 14:22:46 +0200 Subject: [PATCH 3/3] Debugging for NOTIFY --- src/backend/commands/async.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/src/backend/commands/async.c b/src/backend/commands/async.c index 20bed5ca71..597e568c85 100644 --- a/src/backend/commands/async.c +++ b/src/backend/commands/async.c @@ -880,12 +880,20 @@ PreCommit_Notify(void) (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), errmsg("too many notifications in the NOTIFY queue"))); nextNotify = asyncQueueAddEntries(nextNotify); + if (Trace_notify) + elog(DEBUG1, "NOTIFY QUEUE = (%d,%d)...(%d,%d)", + QUEUE_POS_PAGE(QUEUE_TAIL), QUEUE_POS_OFFSET(QUEUE_TAIL), + QUEUE_POS_PAGE(QUEUE_HEAD), QUEUE_POS_OFFSET(QUEUE_HEAD)); /* If we are advancing to a new page, remember this so after the * transaction commits we can attempt to advance the tail * pointer, see ProcessCompletedNotifies() */ if (QUEUE_POS_OFFSET(QUEUE_HEAD) == 0) + { + if (Trace_notify) + elog(DEBUG1, "backendTryAdvanceTail -> true"); backendTryAdvanceTail = true; + } LWLockRelease(AsyncQueueLock); } } @@ -1194,6 +1202,8 @@ ProcessCompletedNotifies(void) * queue, so we try to advance the tail ourselves, possibly waking * up another backend if it is running behind */ backendTryAdvanceTail = false; + if (Trace_notify) + elog(DEBUG1, "backendTryAdvanceTail -> false"); asyncQueueAdvanceTail(); } @@ -2066,6 +2076,8 @@ asyncQueueAdvanceTail(void) int slowbackendid = InvalidBackendId; int slowbackendpid; + if (Trace_notify) + elog(DEBUG1, "asyncQueueAdvanceTail"); /* Advance the tail as far as possible, noting if there is a slow * backend we could kick */ LWLockAcquire(AsyncQueueLock, LW_EXCLUSIVE); @@ -2096,6 +2108,8 @@ asyncQueueAdvanceTail(void) * AsyncQueueLock; which is unlikely but certainly possible. So we * just log a low-level debug message if it happens. */ + if (Trace_notify) + elog(DEBUG1, "waking backend %d (pid %d)", slowbackendid, slowbackendpid); if (SendProcSignal(slowbackendpid, PROCSIG_NOTIFY_INTERRUPT, slowbackendid) < 0) elog(DEBUG3, "could not signal backend with PID %d: %m", slowbackendpid); } -- 2.11.0