Apache's MPM mechanism-prefork

Apache is based on modular design.

The basic service also uses a modular design, but this module is exclusive and can only be called at the same time.

The MPM (multi processing module) multi-processing module is a basic module. It was originally run on the Unix family of operating systems. Later, when porting to other platforms, a module based on the local operating system was selected.

On the Unix family, the prefor, worker, and event three modules are generated depending on whether the thread is supported.

The Prefork module does not use threads and is the most basic.

For a httpd server, in order to provide good external services, the first to start some processes, Prefork mode default is 5. The minimum number of idle processes is 5, the maximum idle process is 10, and the maximum process (maxrequestworkers) is 256.

From this you can see the default configuration in Ubuntu Linux 14.04LTS.

Prefork has 5 items.

The maximum number of processes set is 150.

The connections that each process can serve are set to be unlimited. If you set this number to not 0, you can avoid the amount of memory that may be affected by a possible memory leak.

Apache's MPM mechanism-prefork