threads to synchronise access to a shared resource. A mutex
has two states: locked and unlocked. Once a mutex has been
locked by a thread, other threads attempting to lock it will
block. When the locking thread unlocks (releases) the mutex,
one of the blocked threads will acquire (lock) it and proceed.
If multiple threads or tasks are blocked on a locked mutex
object, the one to take it and proceed when it becomes
available is determined by some type of scheduling algorithm.
For example, in a priority based system, the highest priority
blocked task will acquire the mutex and proceed. Another
common set-up is put blocked tasks on a first-in-first-out
queue.
(2002-03-14)