From: Noah Misch <noah@leadboat.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Francesco Degrassi <francesco.degrassi@optionfactory.net>
Cc: pgsql-bugs@lists.postgresql.org
Subject: Re: Leader backend hang on IPC/ParallelFinish when LWLock held at parallel query start
Date: Thu, 7 Nov 2024 11:38:23 -0800
Message-ID: <20241107193823.dc.nmisch@google.com> (raw)
In-Reply-To: <3459938.1731007759@sss.pgh.pa.us>
References: <CAC-SaSzHUKT=vZJ8MPxYdC_URPfax+yoA1hKTcF4ROz_Q6z0_Q@mail.gmail.com>
<20240918030159.2a.nmisch@google.com>
<1737570.1726633422@sss.pgh.pa.us>
<20240918050434.13.nmisch@google.com>
<3441950.1730999841@sss.pgh.pa.us>
<20241107192233.94.nmisch@google.com>
<3459938.1731007759@sss.pgh.pa.us>
On Thu, Nov 07, 2024 at 02:29:19PM -0500, Tom Lane wrote:
> Noah Misch <noah@leadboat.com> writes:
> > This thread's previous commit just forced a serial plan.
>
> My concern is that the previous commit forced new plans to be serial,
> but did nothing about re-use of an existing plan.
I agree. It solved one way of reaching the problem, leaving at least one
unsolved.
> > The executor
> > counterpart would look like having the executor do what it does when there are
> > no free worker slots.
>
> Ah, that could be a way out. Stick an INTERRUPTS_CAN_BE_PROCESSED()
> call somewhere in there?
Exactly. If !INTERRUPTS_CAN_BE_PROCESSED(), proceed as though no workers can
be launched.
> That could even allow us to revert the
> planner change, which would simplify testing of the executor change.
True.
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To: pgsql-bugs@postgresql.org
Cc: noah@leadboat.com, tgl@sss.pgh.pa.us, francesco.degrassi@optionfactory.net, pgsql-bugs@lists.postgresql.org
Subject: Re: Leader backend hang on IPC/ParallelFinish when LWLock held at parallel query start
In-Reply-To: <20241107193823.dc.nmisch@google.com>
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