Re: [bug fix] "pg_ctl stop" times out when it should respond quickly

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, MauMau <maumau307(at)gmail(dot)com>, Peter Eisentraut <peter_e(at)gmx(dot)net>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [bug fix] "pg_ctl stop" times out when it should respond quickly
Date: 2014-04-05 00:10:16
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Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Mon, Feb 17, 2014 at 11:29 AM, Alvaro Herrera
> <alvherre(at)2ndquadrant(dot)com> wrote:
>> The pg_regress part is ugly. However, pg_regress is doing something
>> unusual when starting postmaster itself, so the ugly coding to stop it
>> seems to match. If we wanted to avoid the ugliness here, the right fix
>> would be to use pg_ctl to start postmaster as well as to stop it.

> I wonder if this would change the behavior in cases where we hit ^C
> during the regression tests. Right now I think that kills the
> postmaster as well as pg_regress, but if we used pg_ctl, it might not,
> because pg_regress uses fork()+exec(), but pg_ctl uses system() to
> launch a shell which is in turn instructed to background the
> postmaster.

After re-reading this thread, I am convinced that this patch is failing
to fix the real problem, which is that the postmaster isn't defending
against early arrival of a signal; see

Hacking pg_ctl is a band-aid solution, and given these concerns,
not a particularly safe band-aid.

I experimented with simply moving postmaster.c's initialization of signals
further up, and that seems to fix the complained-of problem just fine.
It could be an issue if anything in postmaster initialization is expecting
to run with signals unblocked, but I don't know what that would be.
So I suggest we just do the attached.

regards, tom lane

Attachment Content-Type Size
postmaster-block-signals-earlier.patch text/x-diff 3.2 KB

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