What is Apache process model?

Question

I have been googling this question for some time but got no answers. What's the Apache process model?

By process model, I mean how Apache manage process or thread to handling HTTP request.

Does it fork one process for each HTTP request?

Does it have process/thread pool?

Can we config it?

Is there any online doc for such Apache details?

Answer 1

This depends on your system and configuration : see Core Features and Multi-Processing Modules : you could use, for instance :

• Apache MPM winnt on windows -- that one uses threads
• Or Apache MPM prefork -- that one uses processes
• Or even Apache MPM worker -- which uses both several processes and threads.

Quoting the page of the last one, Apache MPM worker :

This Multi-Processing Module (MPM) implements a hybrid multi-process multi-threaded server.
By using threads to serve requests, it is able to serve a large number of requests with fewer system resources than a process-based server.
However, it retains much of the stability of a process-based server by keeping multiple processes available, each with many threads.