Horton

Re: BUG #17103: WAL segments are not removed after exceeding max_slot_wal_keep_size

Alvaro Herrera <alvherre@alvh.no-ip.org>

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From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: jeff.janes@gmail.com, mk@071.ovh, pgsql-bugs@lists.postgresql.org
Date: 2021-07-17T14:28:09Z
Lists: pgsql-bugs

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On 2021-Jul-16, Alvaro Herrera wrote:

> The buildfarm has remained green so far, but clearly this is something
> we need to fix.  Maybe it's as simple as adding the loop we use below,
> starting at line 219.

There are a few failures of this on buildfarm now,

https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=flaviventris&dt=2021-07-16%2022%3A30%3A35
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=desmoxytes&dt=2021-07-16%2021%3A52%3A04
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=dragonet&dt=2021-07-16%2021%3A52%3A05

I am running the test in a loop with the attached; if it doesn't fail in
a few more rounds I'll push it.

There are two instances of a different failure:
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=kittiwake&dt=2021-07-17%2013%3A39%3A43
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=hornet&dt=2021-07-16%2021%3A14%3A14

#   Failed test 'check that segments have been removed'
#   at t/019_replslot_limit.pl line 213.
#          got: '000000010000000000000021'
#     expected: '000000010000000000000022'
# Looks like you failed 1 test of 19.
[23:55:14] t/019_replslot_limit.pl .............. 
Dubious, test returned 1 (wstat 256, 0x100)

I'm afraid about this not being something we can fix with some
additional wait points ...

-- 
Álvaro Herrera              Valdivia, Chile  —  https://www.EnterpriseDB.com/
"La grandeza es una experiencia transitoria.  Nunca es consistente.
Depende en gran parte de la imaginación humana creadora de mitos"
(Irulan)

Commits

  1. Close yet another race condition in replication slot test code

  2. Make new replication slot test code even less racy

  3. Make new replication slot test code less racy

  4. Advance old-segment horizon properly after slot invalidation