GNU Portable Threads

 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
 its own individual program-counter, run-time stack, signal mask and errno
 variable.