Performance Schema rwlock_instances Table
rwlock_instances table lists all read write lock (rwlock) instances that the Performance Schema sees while the server is executing. A read write is a mechanism for ensuring threads can either share access to common resources, or have exclusive access.
The performance_schema_max_rwlock_instances system variable specifies the maximum number of instrumented rwlock objects.
rwlock_instances table contains the following columns:
|Instrument name associated with the read write lock|
|Address in memory of the instrumented lock|
|Count of current read locks held|