Mutex

Mutexes vs. semaphores

1. Priority inversion: If the mutex knows who locked it and is supposed to unlock it, it is possible to promote the priority of that task whenever a higher-priority task starts waiting on the mutex.
2. Premature task termination: Mutexes may also provide deletion safety, where the task holding the mutex cannot be accidentally deleted. (This is also a cost; if the mutex can prevent a task from being reclaimed, then a garbage collector has to monitor the mutex.)
3. Termination deadlock: If a mutex-holding task terminates for any reason, the OS can release the mutex and signal waiting tasks of this condition.
4. Recursion deadlock: a task is allowed to lock a reentrant mutex multiple times as it unlocks it an equal number of times.
5. Accidental release: An error is raised on the release of the mutex if the releasing task is not its owner.