The State Threads is a small application library which provides a
foundation for writing fast and highly scalable Internet applications
(such as web servers, proxy servers, mail transfer agents, and so on) on
UNIX-like platforms. It combines the simplicity of the multithreaded
programming paradigm, in which one thread supports each simultaneous
connection, with the performance and scalability of an event-driven
state machine architecture. In other words, this library offers a
threading API for structuring an Internet application as a state
machine.

The State Threads library is a derivative of the Netscape Portable
Runtime library (NSPR).

WWW: http://state-threads.sourceforge.net/