When you need to control the size of your httpd processes, use one of the two modules, Apache::GTopLimit and Apache::SizeLimit, which kill Apache httpd processes when those processes grow too large or lose a big chunk of their shared memory. The two modules differ in their methods for finding out the memory usage. Apache::GTopLimit relies on the libgtop library to perform this task, so if this library can be built on your platform you can use this module. Apache::SizeLimit includes different methods for different platforms—you will have to check the module's manpage to figure out which platforms are supported.