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: Thomas Munro <thomas.munro@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>, Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Fujii Masao <fujii@postgresql.org>, Postgres hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-02-23T23:16:50Z
Lists: pgsql-hackers 
On Wed, Feb 22, 2023 at 09:48:10PM +1300, Thomas Munro wrote:
> On Tue, Feb 21, 2023 at 5:50 PM Nathan Bossart <nathandbossart@gmail.com> wrote:
>> On Tue, Feb 21, 2023 at 09:03:27AM +0900, Michael Paquier wrote:
>> > Perhaps beginning a new thread with a patch and a summary would be
>> > better at this stage?  Another thing I am wondering is if it could be
>> > possible to test that rather reliably.  I have been playing with a few
>> > scenarios like holding the system() call for a bit with hardcoded
>> > sleep()s, without much success.  I'll try harder on that part..  It's
>> > been mentioned as well that we could just move away from system() in
>> > the long-term.
>>
>> I'm happy to create a new thread if needed, but I can't tell if there is
>> any interest in this stopgap/back-branch fix.  Perhaps we should just jump
>> straight to the long-term fix that Thomas is looking into.
> 
> Unfortunately the latch-friendly subprocess module proposal I was
> talking about would be for 17.  I may post a thread fairly soon with
> design ideas + list of problems and decision points as I see them, and
> hopefully some sketch code, but it won't be a proposal for [/me checks
> calendar] next week's commitfest and probably wouldn't be appropriate
> in a final commitfest anyway, and I also have some other existing
> stuff to clear first.  So please do continue with the stopgap ideas.

I've created a new thread for the stopgap fix [0].

[0] https://postgr.es/m/20230223231503.GA743455%40nathanxps13

-- 
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.