From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: Jeff Janes <jeff.janes@gmail.com>,
        Michael Paquier <michael.paquier@gmail.com>,
        PostgreSQL mailing lists <pgsql-hackers@postgresql.org>
Subject: Re: Reducing pg_ctl's reaction time
In-reply-to: <20170626205853.ezhnmxpotdy3wokm@alap3.anarazel.de>
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Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Mon, 26 Jun 2017 13:58:53 -0700"
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Date: Mon, 26 Jun 2017 17:30:30 -0400
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Andres Freund <andres@anarazel.de> writes:
> It'd be quite possible to address the race-condition by moving the
> updating of the control file to postmaster, to the
> CheckPostmasterSignal(PMSIGNAL_BEGIN_HOT_STANDBY) block. That'd require
> updating the control file from postmaster, which'd be somewhat ugly.

No, I don't like that at all.  Has race conditions against updates
coming from the startup process.

> Perhaps that indicates that field shouldn't be in pg_control, but in the
> pid file?

Yeah, that would be a different way to go at it.  The postmaster would
probably just write the state of the hot_standby GUC to the file, and
pg_ctl would have to infer things from there.

			regards, tom lane


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