From: Tom Lane <tgl@sss.pgh.pa.us>
To: Julien Rouhaud <rjuju123@gmail.com>
cc: Mats Kindahl <mats@timescale.com>, pgsql-bugs@lists.postgresql.org
Subject: Re: Use of signal-unsafe functions from signal handlers
In-reply-to: <20220524123739.6glyxyx4owqpqjnr@jrouhaud>
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Comments: In-reply-to Julien Rouhaud <rjuju123@gmail.com>
	message dated "Tue, 24 May 2022 20:37:39 +0800"
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Date: Tue, 24 May 2022 10:15:55 -0400
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Julien Rouhaud <rjuju123@gmail.com> writes:
> Yes, but it's using ereport with FATAL level, so if it's the top level m=
essage
> the ErrorContext should be in initial state or have been reset previousl=
y, and
> if it's not then the escape hatch will reset the context.  So in any cas=
e there
> will be a guarantee to have at least 8kB available in that context, that=
 any
> palloc will be able to use to format the message.

ereport() itself is just the tip of the iceberg; even if it's safe
(which I concur it isn't), there's also the atexit/on_proc_exit
functions that are likely to be called during shutdown.  So yeah,
this coding is not too safe.  I'm not sure that getting rid of it
would be a net win though, as we'd replace it-might-crash hazards
with it-might-never-exit hazards, from bgworkers that neglect to
respond to ShutdownRequestPending.

			regards, tom lane