#44994 [Com]: exec() produces zombie processes on Windows, hangs Apache

 ID:               44994
 Comment by:       jkflash at gmail dot com
 Reported By:      dbarrett at vistaprint dot com
 Status:           Assigned
 Bug Type:         Program Execution
 Operating System: Windows 2003 Server, 64-bit
 PHP Version:      5.2.6
 Assigned To:      pajoye
 New Comment:

Sorry, I take that last comment back, it still hangs annoyingly
intermittently with shell_exec as well. It's a killer :(


Previous Comments:
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[2008-08-13 01:08:19] jkflash at gmail dot com

PS: shell_exec() DOES seem to work without hanging on my setup, but
none of the others.

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[2008-08-12 23:50:58] jkflash at gmail dot com

I am experiencing this same problem with PHP 5.2.1 running on IIS as an
ISAPI module on Windows Server 2003 R2 SP2. Intermitently (a handful of
times in a hundred) a process started with exec() will appear to
complete ok but remain running in a zombie state. The IIS worker process
that created the process will not respond to any further requests. I
need to either open a new client browser or kill the worker process.

I get the same result with system, passthru, p_open and proc_open.

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[2008-07-29 15:03:40] nobody at dontsendmespam dot com

i can reproduce this problem on a debian server with apache2 and
php5.2.6 running as fcgi

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[2008-07-23 02:02:29] efesar at gmail dot com

I just upgraded from PHP 5.1.2 to 5.2.6, and this exact problem happens
to me. The exec and shell_exec used to work, and now they don't. They
hang the php process, and every subsequent call to exec produces a lost
cmd.exe ... 

Incidentally passthru() causes the same behavior.

Maybe it has something to do with the rotatelogs.exe ... somebody
earlier mentioned that it was waiting on c:\Apache2\logs\error.log ... 


So, basically, we can't run any system calls whatsoever via PHP. I
don't want to use a COM object, because I like portable code ... but
that might be the best step until this bug is fixed.

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[2008-07-07 18:57:12] stephen dot cuppett at sas dot com

I am also experiencing this problem.  I have been able to recreate it
with system() as well as proc_open().  With proc_open() it doesn't seem
to matter if I set bypass_shell or not, just determines whether I have a
dangling cmd.exe process or not...

cmd.exe seems to stop at Wait:UserReq, but that probably doesn't mean
much.

I am able to reproduce it with XAMPP 1.6.6a (PHP 5.2.5) on Windows XP
or Windows Server 2003 (32-bit).

I don't have much to add in terms of documentation as I don't get
anything in the httpd logs, but using the following code snippet:

                protected function runSAS($filename) {
                                $this->log("Requested to run SAS file:
" . $filename, LOG_DEBUG);

                                $toRun  = "\"" . SAS . "\"";
                                $toRun .= " -sysin '" . $filename .
"'";
                                $toRun .= " -CONFIG '" . SASV9CFG .
"'";
                                $toRun .= " -PRINT '" . TEMP_DIR . "/"
. basename($filename) . ".lst'";
                                $toRun .= " -LOG '" . TEMP_DIR . "/" .
basename($filename) . ".log'";
                                $toRun .= " -NOSPLASH";
                                
                                $this->log("SAS command to run: " .
$toRun, LOG_DEBUG);
                                
                                $descriptorspec = array(
                                                0 => array("pipe",
"r"),  // stdin is a pipe that the child will read from
                                                1 => array("pipe",
"w"),  // stdout is a pipe that the child will write to
                                                2 => array("pipe", "w")
  // stderr is a file to write to
                                );
                                
                                $res = proc_open($toRun,
$descriptorspec, $pipes, null, null, array(/*"bypass_shell" =>
true*/));
                                
                                if (is_resource($res)) {
                                                //fwrite($pipes[0],
"exit\n");
                                                //fflush($pipes[0]);
                                                fclose($pipes[0]);
                                                fclose($pipes[1]);
                                                fclose($pipes[2]);
                                                
                                                $return_value =
proc_close($res);
                                                
                                                $this->log("Return
value from SAS: " . $return_value, LOG_DEBUG);
                                }
                }


When it does seem to complete, I'll get this in my log:

2008-06-26 20:23:55 Debug: Return value from SAS: 1

Nothing should come out on the pipes at all and when I set it up to
read those and it completes, there is no data read.  However, in a hang
case, PHP blocks reading STDOUT instead of on proc_close never getting
any data... even if I set the stream to be non-blocking on the pipe
explicitely after proc_open.

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The remainder of the comments for this report are too long. To view
the rest of the comments, please view the bug report online at
    http://bugs.php.net/44994

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