Subject: Re: hang during shutdown

From: Jeremy Schneider <[email-masked]>
Date: Thu, 9 Jul 2026 22:19:55 -0700

On Thu, 9 Jul 2026 09:09:25 +0200
Anthonin Bonnefoy <[email-masked]> wrote:

> As you didn't have a shutdown checkpoint, the symptoms look very
> similar (though you didn't confirm whether you were using logical
> replication, so I'm gonna assume you do).

No logical replication. Are we sure this only impacts logical and not
physical? Thanks for the pointer - interesting one.

We do use physical replication. Replicas were shut down and they closed
their connections to this writer instance around 04:25 just before
pg_ctl stop was executed on the writer itself.

Something was on the writer DB's CPU before shutdown; metrics show total
CPU for that linux namespace (k8s pod) around 0.86 cores until 04:24 and
then the CPU starts dropping when the database shuts down. Bu 04:28 the
CPU is under 0.01 cores and the CPU remains effectively zero until the
processes are SIGKILL'd 30 minutes later.

-Jeremy

-- 
To know the thoughts and deeds that have marked man's progress is to
feel the great heart throbs of humanity through the centuries; and if
one does not feel in these pulsations a heavenward striving, one must
indeed be deaf to the harmonies of life.

Helen Keller, The Story Of My Life, 1902, 1903, 1905, introduction by
Ralph Barton Perry (Garden City, NY: Doubleday & Company, 1954), p90.

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From: Anthonin Bonnefoy <[email-masked]>
Date: Fri, 10 Jul 2026 08:49:17 +0200

> physical? Thanks for the pointer - interesting one.

Yeah, this is only for logical replication. If you didn't have one,
then it's unrelated.

> processes are SIGKILL'd 30 minutes later.

Looking at the last WAL record that was on the whole during shutdown
could be interesting information, if you have it available. If the
shutdown was stuck due to a specific state of the WAL, it could give
you some leads.
Other information could be useful, like the types of writes that
happened after you started the shutdown, or to confirm whether the
RUNNING_XACT you mention is indeed from the autovac and whether it
closed the transaction or not.