Performance Schema mutex_instances Table


The mutex_instances table lists all mutexes that the Performance Schema seeing while the server is executing.

A mutex is a code mechanism for ensuring that threads can only access resources one at a time. A second thread attempting to access a resource will find it protected by a mutex, and will wait for it to be unlocked.

The performance_schema_max_mutex_instances system variable specifies the maximum number of instrumented mutex instances.

NAMEInstrument name associated with the mutex.
OBJECT_INSTANCE_BEGINMemory address of the instrumented mutex.
LOCKED_BY_THREAD_IDThe THREAD_ID of the locking thread if a thread has a mutex locked, otherwise NULL.


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