MPMs - Multi-Processing Model Modules


Discover what are the available MPMs and how they work with mod_perl.

META: This doc is under construction. Owners are wanted. -- pgollucci volunteering

MPMs Overview

The Worker MPM

META: incomplete

You can test whether running under threaded env via: ?

  /* whatever */

When the server is running under the threaded mpm scfg->threaded_mpm is set to true.


All per-server data is shared between threads, regardless of locking, changing the value of something like ap_document_root changes it for all threads. Not just the current process/request, the way it was in 1.3. So we can't really support modification of things like ap_document_root at request time, unless the mpm is prefork. we could support modification of modperl per-server data by using r->request_config in the same way push_handlers et al is implemented. But it is not possible to use this approach for anything outside of modperl (ap_document_root for example).

The Prefork MPM

META: incomplete

The Event MPM


Maintainer is the person(s) you should contact with updates, corrections and patches.

  • Philip M. Gollucci <pgollucci (at)>


  • Stas Bekman [] Philip M. Gollucci <pgollucci (at)>

Only the major authors are listed above. For contributors see the Changes file.