Kills a thread

Creates and runs a thread

Sleeps for a given number of milliseconds

Waits for a thread to end

Creates a semaphore

Destroy semaphore

Create and initialize a semaphore, with an empty wait queue, and couter=' val'

'P' Operation on the 'sem' semaphore'; its counter is decremented; if counter < 0, then the calling task is moved to the wait queue

'V' Operation on the 'sem' semaphore'; its counter is incremented; if counter >= 0 and the wait queue is not empty, then one of the waiting tasks is extracted to continue running