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: 2021-07-19T21:24:48Z
Lists: pgsql-bugs 
On 2021-Jul-19, Kyotaro Horiguchi wrote:

> Sorry for the mistake.  It seems to me the cause the above is that
> segment removal happens *after* invalidation. Since (at least
> currently) the "slot is invalidated" warning issued only at the time
> just before WAL-removal, we should expect that old segments are gone
> after the checkpoint-ending log, which should be seen after
> WAL-removal.  If not, that shows that there's a bug.
> 
> What do you think about the attached?

Sounds sensible -- I verified the logs for one of the cases that failed
in the buildfarm, and indeed the "checkpoint ended" message appears
after the s2 slot is created, so it should fix the problem.  (I didn't
actually try to reproduce the problem locally, so I didn't verify the
fix any further than ensuring the test still passes.)

Pushed, thanks!

-- 
Álvaro Herrera           39°49'30"S 73°17'W  —  https://www.EnterpriseDB.com/

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