X-Spam-Check-By: sourceware.org Date: Thu, 22 Jun 2006 23:05:53 -0400 From: Christopher Faylor To: cygwin AT cygwin DOT com Subject: Re: CygPerl hangs opening FIFO after fork (in both parent&child) Message-ID: <20060623030553.GA8229@trixie.casa.cgf.cx> Reply-To: cygwin AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com References: <449B08E2 DOT 9040302 AT tlinx DOT org> <449B49A2 DOT 7E5EB78B AT dessent DOT net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <449B49A2.7E5EB78B@dessent.net> User-Agent: Mutt/1.5.11 Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm Precedence: bulk List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com Delivered-To: mailing list cygwin AT cygwin DOT com 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. Yep. It's a deadlock which uncovered a race. It should be fixed in the next floor wax available at: http://cygwin.com/snapshots/ And thanks for the test case which illustrated the problem. cgf -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/