mutex

parallel A mutual exclusion object that allows multiple

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.

See also: priority inversion

(2002-03-14)