In computer programming, a mutex (mutual exclusion object)
is a program object that is created so that multiple program
thread can take turns sharing the same resource, such as
access to a file. Typically, when a program is started, it
creates a mutex for a given resource at the beginning by
requesting it from the system and the system returns a
unique name or ID for it. After that, any thread needing the
resource must use the mutex to lock the resource from other
threads while it is using the resource. If the mutex is
already locked, a thread needing the resource is typically
queued by the system and then given control when the mutex
becomes unlocked (when once more, the mutex is locked during
the new thread's use of the resource).