Date: Thu, 10 Feb 2022 14:38:06 -0800
From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Noah Misch <noah@leadboat.com>, Thomas Munro <thomas.munro@gmail.com>,
	pgsql-committers <pgsql-committers@lists.postgresql.org>
Subject: Re: pgsql: TAP tests: check for postmaster.pid anyway when "pg_ctl
 start" f
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Hi,

On 2022-02-10 14:58:57 -0500, Tom Lane wrote:
> So it looks to me like the core problem is that pg_ctl's do_stop()
> is too trusting: if it once sees the postmaster PID as alive, it
> figures that's the end of the story.

Agreed, that's a problem. Even if it wasn't the cause of slot tests on AIX.

kill -9 can be slow on other operating systems as well. I think on linux for
example it's not processed immediately if already in the middle of dumping
core.


> (do_restart and do_promote seem similarly naive ... and why are there so
> many copies of the wait loop, anyway?)

:(

There's generally some confusing duplication in pg_ctl.c itself, and between
pg_ctl and other programs. E.g. CreateRestrictedProcess() existing both in
pg_ctl and slightly differently in restricted_token.c. Wut? Also why is
restricted_token.c in common/, rather than port?


> Another idea is to modify Cluster.pm's kill9 to not return until the
> PID is gone according to kill(0).  On the other hand, that'd mask
> problems like this, so I'm not entirely enthused about changing
> that end of things.

Seems reasonable.

Greetings,

Andres Freund