From: Tom Lane <tgl@sss.pgh.pa.us>
To: Nathan Bossart <nathandbossart@gmail.com>
cc: Amit Kapila <amit.kapila16@gmail.com>,
        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
In-reply-to: <20230110174345.GA1292607@nathanxps13>
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Comments: In-reply-to Nathan Bossart <nathandbossart@gmail.com>
	message dated "Tue, 10 Jan 2023 09:43:45 -0800"
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Date: Sun, 22 Jan 2023 14:12:54 -0500
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Nathan Bossart <nathandbossart@gmail.com> writes:
> On Tue, Jan 10, 2023 at 10:59:14AM +0530, Amit Kapila wrote:
>> I haven't looked in detail but isn't it better to explain somewhere in
>> the comments that it achieves to rate limit the restart of workers in
>> case of error and allows them to restart immediately in case of
>> subscription parameter change?

> I expanded one of the existing comments to make this clear.

I pushed v17 with some mostly-cosmetic changes, including more comments.

> Of course, if the launcher restarts, then the notify_pid will no longer be
> accurate.  However, I see that workers also register a before_shmem_exit
> callback that will send SIGUSR1 to the launcher_pid currently stored in
> shared memory.  (I wonder if there is a memory ordering bug here.)

I think it's all close enough in reality.  There are other issues in
this code, and I'm about to start a new thread about one I identified
while testing this patch, but I think we're in good shape on this
particular point.  I've marked the CF entry as committed.

			regards, tom lane