Hands-On System Programming with Linux

The mutex lock

The word mutex is really an abbreviation for mutual exclusion; to the mutual exclusion of all other (loser) threads, one thread—the winner—holds (or owns) the mutex lock. Only when it is unlocked can another thread take the lock.

An FAQ: What really is the difference between the semaphore and the mutex lock? Firstly, the semaphore can be used in two ways—one, as a counter (with the counting semaphore object), and two (relevant to us here), essentially as a mutex lock—the binary semaphore. Between the binary semaphore and the mutex lock, there exists two primary differences: one, the semaphore is meant to be used to synchronize between processes and not the threads internal to a single process (it is indeed a well-known IPC ...