Date: Thu, 11 Apr 2024 09:42:40 -0500
From: Nathan Bossart <nathandbossart@gmail.com>
To: "Imseih (AWS), Sami" <simseih@amazon.com>
Cc: "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: allow changing autovacuum_max_workers without restarting
Message-ID: <20240411144240.GD1882158@nathanxps13>
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On Thu, Apr 11, 2024 at 02:24:18PM +0000, Imseih (AWS), Sami wrote:
> max_worker_processes defines a pool of max # of background workers allowed.
> parallel workers and extensions that spin  up background workers all utilize from 
> this pool. 
> 
> Should autovacuum_max_workers be able to utilize from max_worker_processes also?
> 
> This will allow autovacuum_max_workers to be dynamic while the user only has
> to deal with an already existing GUC. We may want to increase the default value
> for max_worker_processes as part of this.

My concern with this approach is that other background workers could use up
all the slots and prevent autovacuum workers from starting, unless of
course we reserve autovacuum_max_workers slots for _only_ autovacuum
workers.  I'm not sure if we want to get these parameters tangled up like
this, though...

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