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authorThomas Munro2022-05-11 06:03:03 +0000
committerThomas Munro2022-05-11 06:03:03 +0000
commit0d3431497dbe91ba1e428ace4e9537c109eaff07 (patch)
treea4bc28645a52f87de2fe0d91455238b1d17cd563
parentf95d53eded55ecbf037f6416ced6af29a2c3caca (diff)
Add logging for excessive ProcSignalBarrier waits.
To enable diagnosis of systems that are not processing ProcSignalBarrier requests promptly, add a LOG message every 5 seconds if we seem to be wedged. Although you could already see this state as a wait event in pg_stat_activity, the log message also shows the PID of the process that is preventing progress. Also add DEBUG1 logging around the whole wait loop. Reviewed-by: Robert Haas <[email protected]> Discussion: https://postgr.es/m/CA%2BTgmoYJ03r5359gQutRGP9BtigYCg3_UskcmnVjBf-QO3-0pQ%40mail.gmail.com
-rw-r--r--src/backend/storage/ipc/procsignal.c18
1 files changed, 16 insertions, 2 deletions
diff --git a/src/backend/storage/ipc/procsignal.c b/src/backend/storage/ipc/procsignal.c
index 00d66902d8..21a9fc0fdd 100644
--- a/src/backend/storage/ipc/procsignal.c
+++ b/src/backend/storage/ipc/procsignal.c
@@ -393,6 +393,11 @@ WaitForProcSignalBarrier(uint64 generation)
{
Assert(generation <= pg_atomic_read_u64(&ProcSignal->psh_barrierGeneration));
+ elog(DEBUG1,
+ "waiting for all backends to process ProcSignalBarrier generation "
+ UINT64_FORMAT,
+ generation);
+
for (int i = NumProcSignalSlots - 1; i >= 0; i--)
{
ProcSignalSlot *slot = &ProcSignal->psh_slot[i];
@@ -407,13 +412,22 @@ WaitForProcSignalBarrier(uint64 generation)
oldval = pg_atomic_read_u64(&slot->pss_barrierGeneration);
while (oldval < generation)
{
- ConditionVariableSleep(&slot->pss_barrierCV,
- WAIT_EVENT_PROC_SIGNAL_BARRIER);
+ if (ConditionVariableTimedSleep(&slot->pss_barrierCV,
+ 5000,
+ WAIT_EVENT_PROC_SIGNAL_BARRIER))
+ ereport(LOG,
+ (errmsg("still waiting for backend with PID %lu to accept ProcSignalBarrier",
+ (unsigned long) slot->pss_pid)));
oldval = pg_atomic_read_u64(&slot->pss_barrierGeneration);
}
ConditionVariableCancelSleep();
}
+ elog(DEBUG1,
+ "finished waiting for all backends to process ProcSignalBarrier generation "
+ UINT64_FORMAT,
+ generation);
+
/*
* The caller is probably calling this function because it wants to read
* the shared state or perform further writes to shared state once all