How to limit Apache sub-process memory usage?

Question

— Yeah, just that simple question. It's too easy to consume a lot of RAM in brain-dead mod_XxX (say, mod_php) application, so I'm just wondering what does Apache allow to do as countermeasure.

Answer 1

Apache doesn't, but PHP does allow limiting the maximum amount of memory used, in php.ini. For instance:

memory_limit = 128M

Of course if someone hits this limit the actual amount of RAM used will be slightly higher due to PHP being embedded into Apache.

Answer 2

The ulimit shell feature (which uses the setrlimit system feature) can limit per-process memory use.

On a Debian box, this can be done by adding this to the bottom of /etc/default/apache2:

ulimit -v 1048576

http://feeding.cloud.geek.nz/posts/putting-limit-on-apache-and-php-memory/

See also

• man ulimit
• man setrlimit

Answer 3

I deem it should be considered answered with exactly this quote from the comments: "There isn't one (solution). It depends entirely on the modules you are using" © Michael Hampton