Re: on_exit_reset fails to clear DSM-related exit actions

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Andres Freund <andres(at)2ndquadrant(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: on_exit_reset fails to clear DSM-related exit actions
Date: 2014-03-07 19:14:17
Message-ID: 20945.1394219657@sss.pgh.pa.us
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Andres Freund <andres(at)2ndquadrant(dot)com> writes:
> On 2014-03-07 13:54:42 -0500, Tom Lane wrote:
>> The big picture here is that in the scenario being debated in the other
>> thread, exit() in a child process forked from a backend will execute that
>> backend's on_detach actions *even if the code had done on_exit_reset after
>> the fork*.

> Hm, aren't those actions called via shmem_exit() calling
> dsm_backend_shutdown() et al? I think that should be cleared by
> on_shmem_exit()?

But dsm_backend_shutdown gets called whether or not any shmem_exit
actions are registered.

> I think you're misunderstanding me. I am saying we *should* defend
> against it. Our opinions just seem to differ on what to do when the
> scenario is detected. I am saying we should scream bloody murder (which
> admittedly is a hard in a child), you want to essentially declare it
> supported.

And if we scream bloody murder, what will happen? Absolutely nothing
except we'll annoy our users. They won't have control over the
third-party libraries that are doing what you want to complain about.

regards, tom lane

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