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Date: Thu, 22 Jun 2006 19:52:37 -0700
From: Yitzchak Scott-Thoennes <sthoenna AT efn DOT org>
To: cygwin AT cygwin DOT com
Subject: Re: CygPerl hangs opening FIFO after fork (in both parent&child)
Message-ID: <20060623025236.GA2720@efn.org>
References: <449B08E2 DOT 9040302 AT tlinx DOT org> <449B49A2 DOT 7E5EB78B AT dessent DOT net>
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On Thu, Jun 22, 2006 at 06:53:38PM -0700, Brian Dessent wrote:
> Linda Walsh wrote:
> 
> > The attached test case is simple and fairly short.  It does not
> > depend on File::BOM (and has none of the code from it).
> > 
> > It's only dependency (other than perl) is the POSIX module,
> > where, from, the "fifo" command is taken.
> 
> This appears to be a deadlock in the Cygwin DLL when both the reader and
> writer end of a fifo tries to open the file at the same time (or nearly
> the same time.)  They end up signaling each other to ask about the other
> end of the pipe, and hang there.  It has nothing to do with perl or
> fork, as far as I can tell -- the attached C testcase will work fine if
> the reader end sleeps briefly to ensure the opening order.   It's just a
> classic race condition somewhere.

Good job isolating this problem, Linda and Brian.

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