RE: pipe handling errors

["Nellis, Kenneth" <Kenneth dot Nellis at xerox dot com>]

From: Corinna Vinschen
> Hi Kenneth,
> 
> On Jul 15 13:50, Nellis, Kenneth wrote:
> > From: Corinna Vinschen
> > > On Jul 14 17:40, Nellis, Kenneth wrote:
> > > > When running a bash pipeline using the latest 64-bit packages, I 
> > > > occasionally get output like the following:
> > > > 
> > > > 1479561950 [waitproc] -bash 10000 sig_send: error sending signal 
> > > > 20, pipe handle 0x2710, nb 132, packsize 0, Win32 error 109
> > > > 
> > > <snip>
> > > 
> > > I know that we got this message more often in the past, but I'm 
> > > totally unable to reproduce it these days.  I tried with 1.7.30 as 
> > > well as the latest snapshots.
> > > 
> > > I'm wondering if a pipe could be intercepted by a virus checker or 
> > > something like that.  Whatever it is, would you mind to give the 
> > > latest developer snapshot DLL (2014-07-15) from 
> > > http://cygwin.com/snapshots/ a try?  Chris has fixed a typo in the 
> > > above debug message.  If it still happens for you, maybe the new output helps better to find the cause.
> > 
> > FYI, got it again this morning, this time with the suggested snapshot:
> > 
> >       0 [main] -bash 8812 sig_send: error sending signal -66, pid 
> > 8812, pipe handle 0x80, nb 0, packsize 176, Win32 error 0
> > 
> > Cygwin64> uname -srvmo
> > CYGWIN_NT-6.1 1.7.31s(0.273/5/3) 20140715 09:22:44 x86_64 Cygwin
> > Cygwin64>
> 
> Thanks.  I just created another snapshot which is supposed to fix this issue (curtesy cgf).  Can you give it a try, please?

Well, I'm getting different results with the latest snapshot. Instead of 
getting the error message, I'm getting a hang for maybe a minute before it 
continues.

I used the following command to encourage a failure:

clear; for f in $(find */Debug -name '*Subsystem'); do echo === $f ===; strings $f | grep '\.cpp$' | sort | uniq -c | sort -n; done

9 invocations of this resulted in 3 hangs. During the last such hang, 
ps output showed the following (from a 2nd mintty window):

Cygwin64> ps
      PID    PPID    PGID     WINPID   TTY     UID    STIME COMMAND
     6268   11100    8800      10808  pty0    12779 14:41:03 /usr/bin/sort <defunct>
     1812    2968    1812      10924  pty1    12779 14:41:49 /usr/bin/ps
     2968   10840    2968      10340  pty1    12779 14:41:41 /usr/bin/bash
     5208   11100    8800       5212  pty0    12779 14:41:03 /usr/bin/grep <defunct>
    11196       1   11196      11196  ?       12779 14:37:15 /usr/bin/mintty
     7752   11100    8800      10324  pty0    12779 14:41:03 /usr/bin/sort <defunct>
    10840       1   10840      10840  ?       12779 14:41:41 /usr/bin/mintty
    11100   11196   11100       6260  pty0    12779 14:37:15 /usr/bin/bash
     9536   11100    8800      10368  pty0    12779 14:41:03 /usr/bin/uniq <defunct>
Cygwin64>

After it completed, it showed the following

Cygwin64> ps
      PID    PPID    PGID     WINPID   TTY     UID    STIME COMMAND
     2968   10840    2968      10340  pty1    12779 14:41:41 /usr/bin/bash
    10316    2968   10316       3152  pty1    12779 14:42:08 /usr/bin/ps
    11196       1   11196      11196  ?       12779 14:37:15 /usr/bin/mintty
    10840       1   10840      10840  ?       12779 14:41:41 /usr/bin/mintty
I   11100   11196   11100       6260  pty0    12779 14:37:15 /usr/bin/bash
Cygwin64>

Just to confirm I was using the later snapshot:
Cygwin64> uname -srvmo
CYGWIN_NT-6.1 1.7.31s(0.273/5/3) 20140715 15:34:37 x86_64 Cygwin
Cygwin64>

--Ken Nellis