Re: hang during shutdown

On Mon, Jul 6, 2026 at 8:30 AM Anthonin Bonnefoy
<anthonin(dot)bonnefoy(at)datadoghq(dot)com> wrote:
>
> Hi,
>
> On Sun, Jul 5, 2026 at 11:55 PM Jeremy Schneider
> <schneider(at)ardentperf(dot)com> wrote:
> > so far, it all started with this postgres hang during a shutdown. we didnt capture enough diagnostics to root-cause the domino before the hang, but the data i do have about this postgres hang is very peculiar. i'm working on some automation to gather more diagnostics if there is a recurrence. in the meantime i wanted to share what i do know, in case anyone else has seen something similar.
> >
> > postgres version 16.13
> > Ubuntu 22.04.5 LTS
> > kernel 5.15.0-1110-azure
> >
> > between log messages and wal contents, it appears PostmasterStateMachine transitioned into PM_WAIT_BACKENDS but never progressed beyond this for a full 30 minutes until external automation finally killed the processes.
>
> Did you have an active logical replication stream at the time of the
> shutdown? If so, it's very likely due to a bug in the logical
> walsender[..]

Aren't walsenders in general problematic for shutdowns? (not just logical, of
course it might be this). The PG 19 is going to have
wal_sender_shutdown_timeout, and from description it seems to match [0] to
something like that. 'netstat -ntpo' would help to see from such hanged
system (if walsenders running there at this point at all).

-J.

[0] - https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=a8f45dee91768cf1447ffaf2527e499e75a194c3