CODEWITHSUNDEEP
php
MarcF
MarcF

Reputation: 3299

what may undesireably stop a long running PHP script?

If a long running php script is created in a LAMP stack, using:

set_time_limit(0);
header("Connection: close");
ignore_user_abort(true); // just to be safe
ob_start();

$size = ob_get_length();
header("Content-Length: $size");
ob_end_flush();
flush();            
session_write_close();

//Some long running code here

In what ways could this script subsequently be terminated externally (to the script itself)?

Upvotes: 1

Views: 713

Answers (2)

Kaii
Kaii

Reputation: 20540

The major reasons why your example script would end unexpectedly or undesireably are:

  • reboot and shutdown - this should be ovious.

  • memory limits of PHP, of Apache, or running out of memory on OS level will kill this script.

  • in some setups, there might be limits for used CPU cycles, too.

  • any PHP fatal error that occurs during runtime.

  • kill <pid> with almost any signal (not only kill -9) will terminate the script.

  • If the script is running inside apache using mod_php, then apache restarts would also kill the script.
    Note that each long running script inside apache blocks a worker thread/process, which might be bad for your server performance. This may not apply in a php-fcgi environment!

To prevent some of this:

  • Run the script outside the apache environment.
    I prefer calling echo '/usr/bin/php myscript.php'| at now. (using at scheduler, see manpage)

    at totally detaches your script from apache, so it will still run when the apache process ends.

  • set the PHP memory limit to a high value or infinite. (anything > 512M is generally a bad idea)
    This can be done inside the script.

Upvotes: 3

mariobgr
mariobgr

Reputation: 2201

You can create a bash script, that are running for too long and execute it using a cronjob.

For example:

#!/bin/bash
# This script will kill process which running more than X hours
# egrep: the selected process; grep: hours
PIDS="`ps eaxo bsdtime,pid,comm | egrep "spamd|exim|mysqld|httpd" | grep " 1:" | awk '{print $2}'`"

# Kill the process
echo "Killing spamd, exim, mysqld and httpd processes running more than one hour..."
for i in ${PIDS}; do { echo "Killing $i"; kill -9 $i; }; done;

http://forum.directadmin.com/showthread.php?t=26179

Upvotes: -2

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