Multi Threaded Daemon: Manage the execution of parallel threads

This class can be used to manage the execution of running multiple parallel tasks in PHP using the pcntl extension.

It can start a given number of parallel threads that execute code defined by functions of implementation sub-classes.

The main class can manage the execution of code in critical sections using locks to assure than only one thread executes critical section code at a time.

The class also manages the access to variables that are shared by threads running at the same time.