This is the (non-POSIX) threads package, that uses the basic clone interface
of the Linux-kernel.

Now, what is the difference between threads and
processes? A process runs totaly isolated from the other processes in the
Unix system, it concurrently request resources and is controled by the
operating system such that it does no harm to the other processes.
Interfaceing between processes is cost intensive performance wise.

A thread, on the other hand, is scheduled within the context of _one_ process,
shares most (if not all) of its resources, and has to cooperate with the
other threads in order to do no harm to whole thread group. Interfaceing
between threads is very cheap performance wise, hence, using threads is what
You should do when having _one_ application that needs to do work in
parallel.
