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Re: allow changing autovacuum_max_workers without restarting

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: "Imseih (AWS), Sami" <simseih@amazon.com>, Justin Pryzby <pryzby@telsasoft.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2024-06-03T23:24:27Z
Lists: pgsql-hackers 
Hi,

On 2024-06-03 14:28:13 -0500, Nathan Bossart wrote:
> On Mon, Jun 03, 2024 at 12:08:52PM -0700, Andres Freund wrote:
> > Why do we think that increasing the number of PGPROC slots, heavyweight locks
> > etc by 256 isn't going to cause issues?  That's not an insubstantial amount of
> > memory to dedicate to something that will practically never be used.
> 
> I personally have not observed problems with these kinds of bumps in
> resource usage, although I may be biased towards larger systems where it
> doesn't matter as much.

IME it matters *more* on larger systems. Or at least used to, I haven't
experimented with this in quite a while.

It's possible that we improved a bunch of things sufficiently for this to not
matter anymore.

Greetings,

Andres Freund

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Give up on running with NetBSD/OpenBSD's default semaphore settings.

  2. initdb: Do not report default autovacuum_worker_slots.

  3. Lower default value of autovacuum_worker_slots in initdb as needed.

  4. Allow changing autovacuum_max_workers without restarting.

  5. Reserve a PGPROC slot and semaphore for the slotsync worker process.

  6. Make archiver process an auxiliary process.

  7. Correct the formulas for System V IPC parameters SEMMNI and SEMMNS in docs.