GNU Pth - GNU Portable Threads
Copyright (c) 1999-2003 Ralf S. Engelschall <rse@engelschall.com>

o http://www.gnu.org/software/pth/
o ftp://ftp.gnu.org/gnu/pth/
o http://www.ossp.org/pkg/lib/pth/
o ftp://ftp.ossp.org/pkg/lib/pth/

Pth is a very portable POSIX/ANSI-C based library for Unix platforms
which provides non-preemptive priority-based scheduling for multiple
threads of execution ("multithreading") inside server applications.
All threads run in the same address space of the server application,
but each thread has it's own individual program-counter, run-time
stack, signal mask and errno variable.

The thread scheduling itself is done in a cooperative way, i.e. the
threads are managed by a priority- and event-based non-preemptive
scheduler. The intention is that this way one can achieve better
portability and run-time performance than with preemptive scheduling.
The event facility allows threads to wait until various types of
events occur, including pending I/O on filedescriptors, asynchronous
signals, elapsed timers, pending I/O on message ports, thread and
process termination, and even customized callback functions.

Additionally Pth provides an optional emulation API for POSIX.1c
threads ("pthreads") which can be used for backward compatibility to
existing multithreaded applications.