Leader MPM:

This is an experimental MPM that uses the Leader/Followers design
pattern to coordinate work among threads:
http://deuce.doc.wustl.edu/doc/pspdfs/lf.pdf

As of httpd-2.3, the Leader MPM also incorporates a variant of the
Event MPM's asynchronous socket I/O for keepalive connections.  The
management of pollsets and timeouts is encapsulated within the
io_multiplexer functions, with the aim of eventually supporting
asynchronous write completion.

To use the leader MPM, add "--with-mpm=leader" to the configure
script's arguments when building the httpd.
  
IMPORTANT NOTES:

* At the moment, with the async code under active development, the
  Leader MPM is suitable for R&D use, but not for production use.

* Like the Event MPM, the Leader MPM now requires a threadsafe
  apr_pollset implementation, such as epoll on Linux or kqueue
  on BSD.

