From: Peter Slacik <Peter.Slacik@tatramed.sk>
To: Ross Johnson <rpj@ise.canberra.edu.au>
Cc: Pthreads Developers List <pthreads-win32@sourceware.cygnus.com>
Subject: Re: Pthreads over Win32 / Condition Variables (fwd)
Date: Fri, 15 Oct 1999 05:25:00 -0000 [thread overview]
Message-ID: <38071BF8.1D42C185@TatraMed.sk> (raw)
In-Reply-To: <Pine.LNX.4.05.9910141750340.28647-100000@swan.canberra.edu.au>
Ross Johnson wrote:
> [...] looking at the code I've found another bug nearby.
>
> The internal routine Cond_timedwait, called by pthread_cond_wait and
> pthread_cond_timedwait, is a cancelation point. In case the thread
> is canceled while it's waiting, the code pushes a cleanup handler
> (actually just pthread_mutex_lock) to re-lock the mutex associated
> with the CV. At the moment this is all it does.
>
> The canceled waiting thread doesn't decrement the waiting threads
> count (cv->waiters) and so the count will never get back to zero,
> and the true last waiter will never notify the broadcasting thread.
>
> I suspect the cleanup handler also needs to check if a broadcast is
> in effect and if it's the last waiting thread, and finish off the
> broadcast if it is.
Lorin Hochstein <lmh@xiphos.ca> already informed about this problem (Wed, 30 Jun
1999) and submitted a bugfix. Ross, please check my reply (Thu, 01 Jul 1999)
too.
--
Peter Slacik
next prev parent reply other threads:[~1999-10-15 5:25 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-10-14 21:28 Ross Johnson
1999-10-15 5:25 ` Peter Slacik [this message]
1999-10-16 8:07 ` Ross Johnson
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