Re: Reproducible hang with unusual border conditions

[Christopher Faylor <cgf-no-personal-reply-please at cygwin dot com>]

On Wed, Apr 26, 2006 at 05:39:37PM -0400, Volker Quetschke wrote:
>On my search for the infamous cygwin hang while building OOo,
>see <http://sources.redhat.com/ml/cygwin/2005-12/msg00279.html>,
>and <http://wiki.services.openoffice.org/wiki/Windows#Miscellaneous_info>
>that I couldn't reproduce myself (WJFFM) I finally managed to get a
>reproducible hang on my systems that might be related.
>
>As said, the original OOo build works just fine here, but there is
>an alternative possibility to build OOo with 4nt instead of tcsh, and
>from that I managed to reproduce a small testcase. Unfortunately
>it requires 4nt :(  and some strict/strange border conditions:
>
>1. It only hangs from rxvt. (Invoked with shortlink from desktop to:
>C:\cygwin\bin\rxvt.exe  -cr green -sl 1000 -tn linux -e /usr/bin/bash 
>--login -i)
>I guess the actual switches don't matter.  Startting the following
>example from the bash that is started from the cygwin icon (cygwin.bat)
>didn't show the problem so far.
>
>2. Only hangs for "real" background processes started with setsid. From rxvt
>like this:
>$ setsid ./hang.sh >& hang.log
>
>You need to unpack the following testcase,
><http://www.openoffice.org/nonav/issues/showattachment.cgi/36076/w32-4nt-hang.zip>
>it contains the following files:
>-rwxr-xr-x 1 quetschke None 147456 Apr  3 20:19 dmake.exe
>-rwxr-xr-x 1 quetschke None      3 Apr 26 10:34 hang.XXX$
>-rwxr-xr-x 1 quetschke None 192635 Apr 26 16:45 hang.log
>-rwxr-xr-x 1 quetschke None    285 Apr 26 13:30 hang.mk
>-rwxr-xr-x 1 quetschke None    133 Apr 26 13:22 hang.sh
>
>The dmake.exe is a native w32 version, from a m164 OO build with W32-4nt.
>
>For me, after entering the above command and letting it run for a few 
>minutes,
>I get a 4nt process that is stuck at 99% and no new output reaches hang.log.
>
>It definitely looks like 4nt is hanging, *BUT*
>$ ps
>      PID    PPID    PGID     WINPID  TTY  UID    STIME COMMAND
>     3972       1    3972       3972  con 1006 16:35:12 /usr/bin/rxvt
>I    3996    3972    3996       4008    0 1006 16:35:12 /usr/bin/bash
>     3804       1    3804        736    ? 1006 16:49:29 /usr/bin/bash
>      828    3804    3804       3760    ? 1006 16:52:26
>/cygdrive/d/w1/w32-4nt-hang/dmake
>
>if I kill the calling cygwin script, kill 3804 in this case, 4nt stops to
>loop.
>
>As you can see in hang.mk, I tried to reproduce the hang with cmd.exe, but I
>cannot get to hang that either.
>
>This is a very elusive problem :(

So, if I'm understanding what you're saying correctly, you are seeing a
hang in a non-cygwin process (4nt) which can't be duplicated in a
program with similar functionality (cmd) so therefore, your conclusion
is that there is a cygwin bug?

Please verify what the identity of the actual hung program by running
task manager.  If it really is a non-cygwin program that is having problems
then I'm not tremendously concerned.

cgf

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