SWI-Prolog -- mutex

Availability:built-in

True if Property is a property of MutexId. Defined properties are:

alias(Alias): Mutex has the defined alias name. See mutex_create/2 using the‘alias’option.
status(Status): Current status of the mutex. One of unlocked if the mutex is currently not locked, or locked(Owner, Count) if mutex is locked Count times by thread Owner. Note that unless Owner is the calling thread, the locked status can change at any time. There is no useful application of this property, except for diagnostic purposes.^{bugAs Owner
and Count are fetched separately from the mutex, the values
may be inconsistent.}