Horton

Re: Weird failure with latches in curculio on v15

Nathan Bossart <nathandbossart@gmail.com>

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From: Nathan Bossart <nathandbossart@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andres Freund <andres@anarazel.de>, Thomas Munro <thomas.munro@gmail.com>, Fujii Masao <fujii@postgresql.org>, Michael Paquier <michael@paquier.xyz>, Postgres hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-02-01T16:06:09Z
Lists: pgsql-hackers 
On Wed, Feb 01, 2023 at 10:12:26AM -0500, Tom Lane wrote:
> Andres Freund <andres@anarazel.de> writes:
>> On 2023-02-01 16:21:16 +1300, Thomas Munro wrote:
>>> It's always in proc_exit() in StartupProcShutdownHandler(), a SIGTERM
>>> handler which is allowed to call that while in_restore_command is
>>> true.
> 
>> Ugh, no wonder we're getting crashes. This whole business seems bogus as
>> hell.
> 
> Indeed :-(

Ugh.  My bad.

> The fundamental issue is that we have no good way to break out
> of system(), and I think the original idea was that
> in_restore_command would be set *only* for the duration of the
> system() call.  That's clearly been lost sight of completely,
> but maybe as a stopgap we could try to get back to that.

+1.  I'll produce some patches.

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com

Commits

  1. Avoid calling proc_exit() in processes forked by system().

  2. Move extra code out of the Pre/PostRestoreCommand() section.

  3. Revert refactoring of restore command code to shell_restore.c

  4. Refactor code in charge of running shell-based recovery commands

  5. Clean up inconsistent use of fflush().

  6. Report wait events for local shell commands like archive_command.