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Date: Thu, 27 Jun 2013 13:27:18 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: Failure with fork()
Message-ID: <20130627112718.GC25217@calimero.vinschen.de>
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References: <CAMCbSMqcCEUhjiSsv8CvP1LUdxEHgyS4jJvLjzkSCACAuQ9e2w AT mail DOT gmail DOT com> <51CC2018 DOT 2010608 AT cs DOT utoronto DOT ca>
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User-Agent: Mutt/1.5.21 (2010-09-15)

On Jun 27 07:20, Ryan Johnson wrote:
> On 27/06/2013 5:35 AM, Arjen Markus wrote:
> >Hello,
> >
> >the bug I am reporting here on behalf of Alan Irwin surfaced in the
> >combination wine and Cygwin (Alan summarised it here:
> >http://www.winehq.org/pipermail/wine-devel/2013-June/100328.html). It
> >has to do with the way Cygwin handles forks.
> >
> >The bug can be illustrated with this small program:
> >
> >int main(void) {
> >     while(!fork());
> >     return 0;
> >}
> >
> >It is meant to enable infinite forking, but on Cygwin it immediately
> >stops. I tried
> >it on both Cygwin (not via wine but simply Windows 7) and Linux:
> >- On Linux the program continues without any problem
> >- On Cygwin it stops immediately with an error message that the child process
> >   terminated unexpectedly with some weird return code.
> >
> >Can anyone shed light on this? This bug is a showstopper for the
> >combination wine and Cygwin.
> Out of curiosity, why do you need a fork bomb? Does the script just
> capture the effect of multiple fork calls in quick succession? How
> many forks can you pull off before it croaks, and is that number
> consistent from run to run? I'd be shocked if it really died
> "immediately" -- as in "zero forked children" -- so it would be
> interesting to see if the issue is related to the number of fork
> calls (resource exhaustion of some kind), or just to how quickly
> they run back to back (data race of some kind).

It dies after somewhat below 500 forks and I think I found the reason.
Stay tuned.


Corinna

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

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