From: Rob Browning <rlb@defaultvalue.org>
Cc: guile-devel@gnu.org
Subject: Re: Recursive mutexes?
Date: Sun, 27 Oct 2002 12:44:55 -0600 [thread overview]
Message-ID: <874rb7en6g.fsf@raven.i.defaultvalue.org> (raw)
In-Reply-To: <87iszonmm2.fsf@zagadka.ping.de> (Marius Vollmer's message of "27 Oct 2002 12:32:21 +0100")
Marius Vollmer <mvo@zagadka.ping.de> writes:
> I meant: there is a good reason that waiting on a condition variable
> requires you to have a locked mutex that is the atomically unlocked.
> Without this, I guess you will have a hard time avoiding race
> conditions. Using mutexes in a strange way to simulate this is
> probably wrong.
Ahh, right. I presume you mean the deadlock case of blocking after
you've already been signalled -- yeah mutexes (at least posix style)
aren't the best thing there, but I'd generally use a 0 token sempahore
for that. Then if you're the one about to block, the signaller will
either already have deposited the token, or will after you block.
I have to keep reminding myself that mutexes aren't semaphores here.
I keep forgetting that because I did a whole lot of thread programming
in a system where we arranged for mutexes to be a special case
(one-token) semaphore. This meant it was supposed to be OK for others
to signal, etc.
--
Rob Browning
rlb @defaultvalue.org, @linuxdevel.com, and @debian.org
Previously @cs.utexas.edu
GPG=1C58 8B2C FB5E 3F64 EA5C 64AE 78FE E5FE F0CB A0AD
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prev parent reply other threads:[~2002-10-27 18:44 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-10-26 20:35 Recursive mutexes? Marius Vollmer
2002-10-26 21:39 ` Neil Jerram
2002-10-27 0:03 ` Marius Vollmer
2002-10-27 1:20 ` Thomas Bushnell, BSG
2002-10-27 12:36 ` Marius Vollmer
2002-10-27 7:55 ` Neil Jerram
2002-10-27 18:33 ` Rob Browning
2002-10-26 22:16 ` Rob Browning
2002-10-26 22:29 ` Rob Browning
2002-10-26 22:42 ` Tom Lord
2002-10-26 23:26 ` Thomas Bushnell, BSG
2002-10-26 23:35 ` Tom Lord
2002-10-26 23:50 ` Tom Lord
2002-10-27 1:18 ` Thomas Bushnell, BSG
2002-10-26 22:47 ` Tom Lord
2002-10-27 8:33 ` Neil Jerram
2002-10-27 17:21 ` Tom Lord
2002-10-27 0:35 ` Marius Vollmer
2002-10-27 4:36 ` Rob Browning
2002-10-27 11:32 ` Marius Vollmer
2002-10-27 18:44 ` Rob Browning [this message]
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