From: Michael Paquier <michael@paquier.xyz>
To: Jehan-Guillaume de Rorthais <jgdr@dalibo.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: masao.fujii@oss.nttdata.com
Cc: pgsql-bugs@lists.postgresql.org
Subject: Re: [BUG] non archived WAL removed during production crash recovery
Date: Mon, 27 Apr 2020 16:49:45 +0900
Message-ID: <20200427074945.GG11369@paquier.xyz> (raw)
In-Reply-To: <20200424150300.1b3b0c20@firost>
References: <20200422175824.637bda91@firost>
<20200422181717.491fb499@firost>
<20200422234618.GI33034@paquier.xyz>
<20200423.140546.1055476118690602079.horikyota.ntt@gmail.com>
<20200423185953.5f8e5b8f@firost>
<20200423235402.GJ33034@paquier.xyz>
<25921.1587694875@sss.pgh.pa.us>
<20200424034248.GL33034@paquier.xyz>
<20200424150300.1b3b0c20@firost>
On Fri, Apr 24, 2020 at 03:03:00PM +0200, Jehan-Guillaume de Rorthais wrote:
> I agree the three tests could be removed as they were not covering the bug we
> were chasing. However, they might still be useful to detect futur non expected
> behavior changes. If you agree with this, please, find in attachment a patch
> proposal against HEAD that recreate these three tests **after** a waiting loop
> on both standby1 and standby2. This waiting loop is inspired from the tests in
> 9.5 -> 10.
FWIW, I would prefer keeping all three tests as well.
So.. I have spent more time on this problem and mereswin here is a
very good sample because it failed all three tests:
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=mereswine&dt=2020-04-24%2006%3A03%3A53
For standby2, we get this failure:
ok 11 - .ready file for WAL segment 000000010000000000000001 existing
in backup is kept with archive_mode=always on standby
not ok 12 - .ready file for WAL segment 000000010000000000000002
created with archive_mode=always on standby
Then, looking at 020_archive_status_standby2.log, we have the
following logs:
2020-04-24 02:08:32.032 PDT [9841:3] 020_archive_status.pl LOG:
statement: CHECKPOINT
[...]
2020-04-24 02:08:32.303 PDT [9821:7] LOG: restored log file
"000000010000000000000002" from archive
In this case, the test forced a checkpoint to test the segment
recycling *before* the extra restored segment we'd like to work on was
actually restored. So it looks like my initial feeling about the
timing issue was right, and I am also able to reproduce the original
set of failures by adding a manual sleep to delay restores of
segments, like that for example:
--- a/src/backend/access/transam/xlogarchive.c+++ b/src/backend/access/transam/xlogarchive.c@@ -74,6 +74,8 @@ RestoreArchivedFile(char *path, const char *xlogfname,
if (recoveryRestoreCommand == NULL ||
strcmp(recoveryRestoreCommand, "") == 0)
goto not_available;
+ pg_usleep(10 * 1000000); /* 10s */
+
/*
With your patch the problem does not show up anymore even with the
delay added, so I would like to apply what you have sent and add back
those tests. For now, I would just patch HEAD though as that's not
worth the risk of destabilizing stable branches in the buildfarm.
> $primary->poll_query_until('postgres',
> q{SELECT archived_count FROM pg_stat_archiver}, '1')
> - or die "Timed out while waiting for archiving to finish";
> + or die "Timed out while waiting for archiving to finish";
Some noise in the patch. This may have come from some unfinished
business with pgindent.
--
Michael
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To: pgsql-bugs@postgresql.org
Cc: michael@paquier.xyz, jgdr@dalibo.com, tgl@sss.pgh.pa.us, horikyota.ntt@gmail.com, masao.fujii@oss.nttdata.com, pgsql-bugs@lists.postgresql.org
Subject: Re: [BUG] non archived WAL removed during production crash recovery
In-Reply-To: <20200427074945.GG11369@paquier.xyz>
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