Date: Wed, 14 Dec 2022 09:45:35 -0800
From: Nathan Bossart <nathandbossart@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Melih Mutlu <m.melihmutlu@gmail.com>,
	Thomas Munro <thomas.munro@gmail.com>,
	"Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: wake up logical workers after ALTER SUBSCRIPTION
Message-ID: <20221214174535.GA773264@nathanxps13>
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On Wed, Dec 14, 2022 at 12:42:32PM -0500, Tom Lane wrote:
> Nathan Bossart <nathandbossart@gmail.com> writes:
>> My first thought is that the latter two uses should be moved to a new
>> parameter, and the apply launcher should store the last start time for each
>> apply worker like the apply workers do for the table-sync workers.  In any
>> case, it probably makes sense to lower this parameter's value for testing
>> so that tests that restart these workers frequently aren't waiting for so
>> long.
> 
>> I can put a patch together if this seems like a reasonable direction to go.
> 
> No, I'm still of the opinion that waiting for the launcher to timeout
> before doing something is fundamentally wrong design.  We should signal
> it when we want it to do something.  That's not different from what
> you're fixing about the workers; why don't you see that it's appropriate
> for the launcher too?

I'm reasonably certain the launcher is already signaled like you describe.
It'll just wait to start new workers if it's been less than
wal_retrieve_retry_interval milliseconds since the last time it started
workers.

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