On Sat, Mar 7, 2015 at 10:18 PM, Tatsuo Ishii <is...@postgresql.org> wrote: > > When I set log_min_messages to debug5 and looked into walreciver log, > I saw this: > > 3600 2015-03-08 09:47:38 JST DEBUG: sendtime 2015-03-08 09:47:38.31493+09 receipttime 2015-03-08 09:47:38.315027+09 replication apply delay -1945478837 ms tran sfer latency 0 ms > > The "replication apply delay -1945478837 ms" part looks strange > because the delay is below 0. The number is formatted as %d in elog > call, and I suspect this is kind of integer overflow. >
Looking at GetReplicationApplyDelay() in walreceiverfuncs.c I noticed that the integer overflow occurs because sometimes the return of the GetCurrentChunkReplayStartTime() is 0 (zero). I added an elog into GetReplicationApplyDelay to check this info: DEBUG: GetReplicationApplyDelay 479099832 seconds, 352 milliseconds, (0.000000, 479099832352083.000000) DEBUG: sendtime 2015-03-08 00:17:12.351987-03 receipttime 2015-03-08 00:17:12.352043-03 replication apply delay -1936504800 ms transfer latency 0 ms DEBUG: GetReplicationApplyDelay 479099841 seconds, 450 milliseconds, (0.000000, 479099841450320.000000) DEBUG: sendtime 2015-03-08 00:17:21.45018-03 receipttime 2015-03-08 00:17:21.450294-03 replication apply delay -1936495702 ms transfer latency 0 ms Maybe we should check before and return zero from GetReplicationApplyDelay. The attached patch implement it. Regards, -- Fabrízio de Royes Mello Consultoria/Coaching PostgreSQL >> Timbira: http://www.timbira.com.br >> Blog: http://fabriziomello.github.io >> Linkedin: http://br.linkedin.com/in/fabriziomello >> Twitter: http://twitter.com/fabriziomello >> Github: http://github.com/fabriziomello
diff --git a/src/backend/replication/walreceiverfuncs.c b/src/backend/replication/walreceiverfuncs.c index 496605f..0c45b66 100644 --- a/src/backend/replication/walreceiverfuncs.c +++ b/src/backend/replication/walreceiverfuncs.c @@ -328,6 +328,8 @@ GetReplicationApplyDelay(void) long secs; int usecs; + TimestampTz chunckReplayStartTime; + SpinLockAcquire(&walrcv->mutex); receivePtr = walrcv->receivedUpto; SpinLockRelease(&walrcv->mutex); @@ -337,7 +339,12 @@ GetReplicationApplyDelay(void) if (receivePtr == replayPtr) return 0; - TimestampDifference(GetCurrentChunkReplayStartTime(), + chunckReplayStartTime = GetCurrentChunkReplayStartTime(); + + if (chunckReplayStartTime == 0) + return 0; + + TimestampDifference(chunckReplayStartTime, GetCurrentTimestamp(), &secs, &usecs);
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