From: Maxime Devos <maximedevos@telenet.be>
To: "Ludovic Courtès" <ludo@gnu.org>
Cc: 56674@debbugs.gnu.org
Subject: bug#56674: [Shepherd] Use of ‘waitpid’, ‘system*’, etc. in service code can cause deadlocks
Date: Sat, 13 Aug 2022 16:59:55 +0200 [thread overview]
Message-ID: <f13570c6-95bc-548b-5084-8f727efe5881@telenet.be> (raw)
In-Reply-To: <87fsiujwzo.fsf@gnu.org>
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On 21-07-2022 17:39, Ludovic Courtès wrote:
>> Alternatively:
>>
>> 4. Do the waitpid in a separate thread (needs work-around for the
>> multi-threaded fork problem, probably C things? Or modifying Guile and
>> maybe glibc to avoid async-unsafe things or make more things
>> async-safe or whatever the appropriate ...-safe is here.)
> For shepherd, multithreading is not an option due to the semantics of
> fork in the presence of threads.
From what I've read, multi-threaded fork is safe as long as you do an
exec 'immediately' afterwards, without doing things like taking locks or
allocating memory with malloc in-between the fork and exec. I don't
think it's possible to do that in Guile code, but that's what the C
things are for.
Greetings,
Maxime.
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next prev parent reply other threads:[~2022-08-13 15:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-20 21:39 bug#56674: [Shepherd] Use of ‘waitpid’, ‘system*’, etc. in service code can cause deadlocks Ludovic Courtès
2022-07-20 23:48 ` Maxime Devos
2022-07-21 15:39 ` Ludovic Courtès
2022-08-13 14:59 ` Maxime Devos [this message]
2022-11-13 23:16 ` Ludovic Courtès
2022-11-14 16:32 ` bug#58926: Shepherd becomes unresponsive after an interrupt Ludovic Courtès
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