Hi Ken, On Jun 8 12:20, Ken Brown wrote: > On 6/7/2019 5:43 PM, Ken Brown wrote: > > On 6/7/2019 3:13 PM, Ken Brown wrote: > >> On 6/7/2019 2:31 PM, Achim Gratz wrote: > >>> Ken Brown writes: > >>>> I think I've found the problem. I was mishandling signals that arrived > >>>> during a > >>>> read. But after I fix that, there's still one nagging issue involving > >>>> timerfd > >>>> code. I'll write to the main list with details. I *think* it's a > >>>> timerfd bug, > >>>> but it's puzzling that I only see it when testing my new pipe > >>>> implementation. > >>> > >>> Anything triggering a race or deadlock will depend on so many other > >>> things that it really is no surprise to see seemingly unrelated changes > >>> making the bug appear or disappear. There are certainly races left in > >>> Cygwin, I see them from time to time in various Perl modules, just never > >>> reproducible enough to give anyone an idea of where to look. > >> > >> That makes sense. > >> > >> In the meantime, I've already discovered another problem, within an hour of > >> posting my claim that everything was working fine: If I start emacs-X11 > >> with > >> cygserver running, I can't fork any subprocesses within emacs. I get > >> > >> 0 [main] emacs 2689 dofork: child 2693 - died waiting for dll loading, > >> errno 11 > >> > >> Back to the drawing board.... I've never looked at the cygserver code, but > >> maybe it will turn out to be something easy. > > > > Good news (for me): This isn't related to my pipe code. The same problem > > occurs > > if I build the master branch. I'll bisect when I get a chance (probably > > tomorrow). In the meantime, all I can say is that strace shows a > > STATUS_ACCESS_VIOLATION at shm.cc:125. > > A bisection shows that the problem starts with the following commit:
Thanks for bisecting! > commit f03ea8e1c57bd5cea83f6cd47fa02870bdfeb1c5 > Author: Michael Haubenwallner <michael.haubenwall...@ssi-schaefer.com> > Date: Thu May 2 12:12:44 2019 +0200 > > Cygwin: fork: Remember child not before success. > > Do not remember the child before it was successfully initialized, or we > would need more sophisticated cleanup on child initialization failure, > like cleaning up the process table and suppressing SIGCHILD delivery > with multiple threads ("waitproc") involved. Compared to that, the > potential slowdown due to an extra yield () call should be negligible. Please revert the patch for the time being. Michael, this needs some more work, apparently. Corinna -- Corinna Vinschen Cygwin Maintainer
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