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Date: Wed, 6 Oct 2010 22:27:42 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: Cygwin >= 1.7.6 open message queues - permission denied
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On Oct  6 13:21, Corinna Vinschen wrote:
> On Oct  6 10:13, Manuel Wienand wrote:
> > Hi,
> > 
> > I noticed that I get a permission denied error when I try to open a message queue in the same process or
> > in an other process.
> > The problem can be reproduced using the code given at: http://sourceware.org/ml/cygwin/2009-09/msg00629.html
> 
> Confirmed.  I'll investigate.

Fixed in CVS.  While debugging I found a subtile synchronization problem
in the message queue implementation which apparently never was a problem
in W. Richard Stevens original implementation.  Under some circumstances
a deadlock could occur because the Windows scheduler didn't give any
time to another process waiting for the same event object.  I fixed that
now by splitting the single event object which was used to signal both,
a full as well as an empty queue. into two separate event objects.  So,
that's why the fix took a while longer than anticipated.


Corinna

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Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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