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| author | Noah Misch <noah@leadboat.com> | 2020-04-25 10:18:12 -0700 |
|---|---|---|
| committer | Noah Misch <noah@leadboat.com> | 2020-04-25 10:18:12 -0700 |
| commit | f246ea3b2a5e0b75e44f0f18157c4b5e10b5547f (patch) | |
| tree | 3570f7790e1244103ce570bbfc8f2171a22f8875 /src | |
| parent | 72a3dc321d76c93842d502793f93b9dc2d2305b2 (diff) | |
| download | postgresql-f246ea3b2a5e0b75e44f0f18157c4b5e10b5547f.tar.gz postgresql-f246ea3b2a5e0b75e44f0f18157c4b5e10b5547f.zip | |
In caught-up logical walsender, sleep only in WalSndWaitForWal().
Before sleeping, WalSndWaitForWal() sends a keepalive if MyWalSnd->write
< sentPtr. When the latest physical LSN yields no logical replication
messages (a common case), that keepalive elicits a reply. Processing
the reply updates pg_stat_replication.replay_lsn. WalSndLoop() lacks
that; when WalSndLoop() slept, replay_lsn advancement could stall until
wal_receiver_status_interval elapsed. This sometimes stalled
src/test/subscription/t/001_rep_changes.pl for up to 10s.
Reviewed by Fujii Masao and Michael Paquier.
Discussion: https://postgr.es/m/20200418070142.GA1075445@rfd.leadboat.com
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/replication/walsender.c | 20 |
1 files changed, 11 insertions, 9 deletions
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c index 0813c830269..6c87f6087ce 100644 --- a/src/backend/replication/walsender.c +++ b/src/backend/replication/walsender.c @@ -1428,8 +1428,10 @@ WalSndWaitForWal(XLogRecPtr loc) /* * We only send regular messages to the client for full decoded * transactions, but a synchronous replication and walsender shutdown - * possibly are waiting for a later location. So we send pings - * containing the flush location every now and then. + * possibly are waiting for a later location. So, before sleeping, we + * send a ping containing the flush location. If the receiver is + * otherwise idle, this keepalive will trigger a reply. Processing the + * reply will update these MyWalSnd locations. */ if (MyWalSnd->flush < sentPtr && MyWalSnd->write < sentPtr && @@ -2314,14 +2316,14 @@ WalSndLoop(WalSndSendDataCallback send_data) WalSndKeepaliveIfNecessary(); /* - * We don't block if not caught up, unless there is unsent data - * pending in which case we'd better block until the socket is - * write-ready. This test is only needed for the case where the - * send_data callback handled a subset of the available data but then - * pq_flush_if_writable flushed it all --- we should immediately try - * to send more. + * Block if we have unsent data. XXX For logical replication, let + * WalSndWaitForWal() handle any other blocking; idle receivers need + * its additional actions. For physical replication, also block if + * caught up; its send_data does not block. */ - if ((WalSndCaughtUp && !streamingDoneSending) || pq_is_send_pending()) + if ((WalSndCaughtUp && send_data != XLogSendLogical && + !streamingDoneSending) || + pq_is_send_pending()) { long sleeptime; int wakeEvents; |