Date: Wed, 23 Mar 2022 15:25:48 +0900
From: Michael Paquier <michael@paquier.xyz>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: Magnus Hagander <magnus@hagander.net>,
	"Bossart, Nathan" <bossartn@amazon.com>,
	Fujii Masao <masao.fujii@oss.nttdata.com>,
	Justin Pryzby <pryzby@telsasoft.com>,
	Andres Freund <andres@anarazel.de>,
	Mark Dilger <mark.dilger@enterprisedb.com>,
	Don Seiler <don@seiler.us>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: Estimating HugePages Requirements?
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On Tue, Mar 15, 2022 at 03:44:39PM -0700, Nathan Bossart wrote:
> A simple approach could be to just set log_min_messages to PANIC before
> exiting.  I've attached a patch for this.  With this patch, we'll still see
> a FATAL if we try to use 'postgres -C' for a runtime-computed GUC on a
> running server, and there will be no extra output as long as the user sets
> log_min_messages to INFO or higher (i.e., not a DEBUG* value).  For
> comparison, 'postgres -C' for a non-runtime-computed GUC does not emit
> extra output as long as the user sets log_min_messages to DEBUG2 or higher.

>  		puts(config_val ? config_val : "");
> +
> +		/* don't emit shutdown messages */
> +		SetConfigOption("log_min_messages", "PANIC", PGC_INTERNAL, PGC_S_OVERRIDE);
> +
>  		ExitPostmaster(0);

That's fancy, but I don't like that much.  And this would not protect
either against any messages generated before this code path, either,
even if that should be enough for the current HEAD .

My solution for the docs is perhaps too confusing for the end-user,
and we are talking about a Linux-only thing here anyway.  So, at the
end, I am tempted to just add the "2> /dev/null" as suggested upthread
by Nathan and call it a day.  Does that sound fine?
--
Michael

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