ID: 44994
User updated by: dbarrett at vistaprint dot com
Reported By: dbarrett at vistaprint dot com
Status: Open
Bug Type: Reproducible crash
Operating System: Windows 2003 Server, 64-bit
PHP Version: 5.2.6
New Comment:
I replaced all occurrences of exec() and shell_exec() in MediaWiki with
calls to a custom COM object that invokes programs. The problem went
away. This strongly suggests that PHP's implementation of exec(0 and
shell_exec() is the culprit. I suspect a race condition.
Previous Comments:
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[2008-05-14 15:09:43] dbarrett at vistaprint dot com
Description:
------------
This is an intermittent but fatal problem. I cannot reproduce it on
demand, but it occurs regularly on our MediaWiki 1.12.0 site running on
Apache 2.2.8.
When invoking a non-interactive Microsoft Windows command via exec() or
shell_exec(), sometimes the resulting process will hang. Once this
occurs, most or all subsequent exec() calls (within the same Apache
instance) will hang as well. Eventually the wiki becomes unusable. The
only way to kill these processes is to restart Apache. Other
traditional "kill" techniques fail.
This is not the same as Bug #30794, which was about interactive
commands like Notepad. I'm speaking of diverse shell commands like
perl.exe, gnuplot.exe, latex.exe, and others. All of them process text
input, if that matters.
If the process is "foo" and you run exec("foo"), you wind up with
several hung processes:
foo.exe
cmd.exe*32
This may be a race condition. I ran the "handle" utility (from
sysinternals) on the hung processes. It seemed to indicate that the
processes were waiting on c:\Apache2\logs\error.log. Then handle itself
(handle64.exe) hung!
Because this is an intermittent problem, I am looking for advice on how
to debug it and report more detailed information to you. Please don't
append the generic "install the latest snapshot and let us know if the
problem is still there" message to this ticket, because I can't install
an experimental PHP release on a production server, and the problem
happens ONLY on our production server (probably because of the load),
not on any of our development or test servers.
Expected result:
----------------
exec() and shell_exec() should never hang.
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Edit this bug report at http://bugs.php.net/?id=44994&edit=1
