From: Xavier Leroy <xavier.leroy@inria.fr>
To: Alessandro Baretta <alex@baretta.com>
Cc: Ocaml <caml-list@inria.fr>
Subject: Re: [Caml-list] Question on Mutexes
Date: Thu, 20 Mar 2003 16:13:31 +0100 [thread overview]
Message-ID: <20030320161331.B23584@pauillac.inria.fr> (raw)
In-Reply-To: <3E772105.2000307@baretta.com>; from alex@baretta.com on Tue, Mar 18, 2003 at 02:37:09PM +0100
> If thread t1 locks mutex m, can thread t2 unlock it?
> I ask because I get no sign of exceptions being thrown when
> I execute the following code in the toplevel:
> [...]
> Is this a bug or a feature? Are threads supposed to be able
> to unlock mutexes held by _other_ threads?
No, but this isn't necessarily checked.
The bytecode-level implementation of the thread library doesn't check,
and will actually work correctly if thread A locks the mutex and
thread B unlocks it.
The system-level implementation of the thread library is a thin
wrapper around POSIX or Win32 mutexes. The POSIX spec says that the
behavior of unlocking by another thread than the one that locked is
undefined: some implementations can signal an error, others can "do
the right thing", others can crash.
- Xavier Leroy
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next prev parent reply other threads:[~2003-03-20 15:13 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-03-18 13:37 Alessandro Baretta
2003-03-18 18:43 ` David Brown
2003-03-20 15:13 ` Xavier Leroy [this message]
2003-03-24 11:19 ` Alessandro Baretta
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