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Re: 64bit cygwin 2.4.0-0.4 hangs when pinging unresponsive host


On Nov 26 21:15, Corinna Vinschen wrote:
> On Nov 25 22:01, Marco Atzeri wrote:
> > 
> > 
> > On 25/11/2015 12:03, Marco Atzeri wrote:
> > >On 25/11/2015 08:06, Thomas Wolff wrote:
> > >>Am 24.11.2015 um 23:29 schrieb Marco Atzeri:
> > >>>
> > >
> > >>>...
> > >>>I assume it is an interaction with mintty.
> > >>Many problems of that kind attributed to mintty are actually problems
> > >>with cygwin or especially pty.
> > >>Please test also with another terminal (xterm, rxvt, ...).
> > >>Also some more details could be helpful as I cannot reproduce the issue
> > >>(output of `type ping`, actual host pinged).
> > >>------
> > >>Thomas
> > >
> > >you are right is not a mintty only issue.
> > >Same happens in xterm
> > >
> > >
> > >$ which ping
> > >/usr/bin/ping
> > >
> > >$ ping 2.2.2.2
> > >PING 2.2.2.2 (2.2.2.2): 56 data bytes
> > >
> > >It sticks here forever, CTRL+C ineffective.
> > >Process Explorer or Task Manager are needed to kill the process.
> > >Also kill -9 PID is ineffective
> > >
> > >On the old cygwin.bat (aka windows cmd)
> > >CTRL+C is effective
> > >
> > >  64 $ ping 2.2.2.2
> > >PING 2.2.2.2 (2.2.2.2): 56 data bytes
> > >
> > >----2.2.2.2 PING Statistics----
> > >2 packets transmitted, 0 packets received, 100.0% packet loss
> > 
> > 
> > the problem seems restricted to the 64bit test version of cygwin.
> 
> I think this is pure coincidence.  After some hours debugging this
> problem it seems it's a race condition, architecture-independent and
> present since quite a while in Cygwin.  In case of ping the race leads
> to a blocking socket function missing a signal arrived, thus the
> signal is never handled.  This in turn blocks the next signal from being
> delivered.
> 
> I have a potential fix, but I have to test it a bit.  The signal code
> is pretty complicated...

I created a new developer snapshot (https://cygwin.com/snapshots/) and
I'm just about writing the release message for the next test release
2.4.0-0.5 which both contain a patch for this problem.  Please give
any of them a try.


Thanks,
Corinna

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

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