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John Hunt
Asked: 2011-03-27 03:03:06 +0800 CST

Bad php scripts bringing server to a stand still

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I have a pretty standard LAMP setup on my Debian VPS. The VPS has 512MB of ram, and I've assigned 128MB in my php.ini for php.

If I create a script with an infinite loop in it the VPS pretty much comes to a standstill (SSH stops being responsive etc..)

I was wondering if there's a way to lower PHP's priority or something like that so that bad scripts can't interfere too much with the server.

Thanks, John.

php lamp

2 Answers

  1. You actually have two options here, depending on how you run this. One solution is to limit the runtime of PHP scripts--that is, you can have a PHP script terminate automatically based on its actual run time.

    If you're running this from a web server (Apache, Lighttpd, etc.), you can use the max_execution_time parameter. By default, this is 30 seconds. If you're running this from the CLI, use the set_time_limit function.

    Another solution is to use something such as monit to monitor the load and CPU usage of the PHP process and kill it if it gets to a specified level.

    Hope this helps; although it might be a good idea to eliminate these kinds of logic errors from your scripts entirely.

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  2. Use nice or renice on the webserver process if PHP is running as a module (e.g. mod_php). This will allow PHP to use more resources when they are available, but will prioritize other processes which may need them.

    I should add that this is only for Linux, and maybe UNIX.

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