Fork issue with timerfd

[Corinna Vinschen]

On Feb 26 00:01, Ken Brown wrote:
> On 2/25/2019 3:20 PM, Corinna Vinschen wrote:
> > On Feb 25 11:03, Corinna Vinschen wrote:
> >> On Feb 25 03:21, Ken Brown wrote:
> >>> On 2/24/2019 9:23 PM, Ken Brown wrote:
> >>>> On 2/24/2019 2:52 PM, Corinna Vinschen wrote:
> >>>>> On Feb 24 20:09, Corinna Vinschen wrote:
> >>>>>> On Feb 24 19:55, Corinna Vinschen wrote:
> >>>>>>> On Feb 24 17:27, Ken Brown wrote:
> >>>>>>>> I'm seeing sporadic errors like this on 64-bit Cygwin when I first start emacs:
> >>>>>>>>
> >>>>>>>>           0 [main] emacs-X11 864 C:\cygwin64\bin\emacs-X11.exe: *** fatal error in
> >>>>>>>> forked process - Can't recreate shared timerfd section during fork!
> >>>>>>>>           0 [main] emacs 860 dofork: child 864 - died waiting for dll loading, errno 11
> >>>>>>>>
> >>>>>>>> If I exit and restart, everything will be fine almost every time.
> >>>>>>>
> >>>>>>> I think I see where the thinko was here.  Can you try this?
> >>>>[...]
> >>>> It's better, but not completely fixed.  At the moment I'm testing 32-bit only,
> >>>> [...]
> >>> I withdraw that statement.  After further tries, it's back to happening every time.
> >>>
> > [...]
> > I pushed a patch and uploaded new developer snapshots to
> > https://cygwin.com/snapshots/
> 
> The x86 fork problem seems to be fixed.  I started emacs several times and 
> listed directories without any failure.

Thanks for testing!

> I did get the following, however, during one of the trials (while emacs was idle):
> 
> 1 [main] emacs 246 C:\Users\kbrown\src\emacs\i686-emacs26\src\emacs.exe: *** 
> fatal error - CreateThread failed for pipesel - 0x0<0x0>, Win32 error 8

It's hard to imagine how this is related.  CreateThread fails due to
memory problems?!?  A timerfd does not use a lot of resources, just a
96 bytes struct on the cygheap, a single page shared memory region, and
a thread per timerfd.  This include dup'ed descriptors which share the
timerfd resources with their sibling descriptors.


Corinna

-- 
Corinna Vinschen
Cygwin Maintainer
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