by
Zaid Rabab'a , Software Development Team Leader , Al-Safa Co. Ltd.
Multi-threaded (worker) : 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.
pre-forked : implements a non-threaded, pre-forking web server that handles requests in a manner similar to Apache 1.3. It is appropriate for sites that need to avoid threading for compatibility with non-thread-safe libraries. It is also the best MPM for isolating each request, so that a problem with a single request will not affect any other.
i think (multi-threaded - worker ) is much stable