Date: Thu, 18 Sep 2008 21:22:04 +0200 From: David Naylor <naylor.b.david@gmail.com> To: Julian Elischer <julian@elischer.org> Cc: freebsd-current@freebsd.org Subject: Re: FreeBSD deadlock (with fork?) Message-ID: <200809182122.08221.naylor.b.david@gmail.com> In-Reply-To: <48D2807A.1050106@elischer.org> References: <200809180631.47071.naylor.b.david@gmail.com> <48D2807A.1050106@elischer.org>
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[-- Attachment #1 --] On Thursday 18 September 2008 18:23:22 you wrote: > David Naylor wrote: > > Hi, > > > > I have a program that spawns a lot of subprocesses (with pipes open) from > > multiple threads. The problem is the program often deadlocks, but not > > consistently. Sometimes the program can run over 5 times to competition > > without incidence and yet othertimes it locks within a few seconds. > > you sent this to -current. Is it in -current? (we fixed something like > this some months back in current and 7) -current cvsuped about Tuesday. > do your post-fork processes do an exec? according to the spec they > should. Yes, they do. See the other replies... > if any of your threads other than the one that did the fork ho;ds any > mutex at teh time of fork then your process will hang. If they hold a > umtx (between processes) then everything will hang. Yes, the system does make use of mutexes. The forking thread never holds a mutex but other threads could hold a mutex. This would explain the problem. Is there any way to get around it (i.e. make sure no mutexes are held when a fork is called?) [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) iD8DBQBI0qpgUaaFgP9pFrIRAljRAJ4yB8YgGU5m4DcNCr0mt5GVX1mmuACfTPPo phWECfLkfwuS8eaW/LqLsP8= =1pKp -----END PGP SIGNATURE-----help
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