20.9.2. Performance Schema Instance Tables

20.9.2.1. The cond_instances Table
20.9.2.2. The file_instances Table
20.9.2.3. The mutex_instances Table
20.9.2.4. The rwlock_instances Table
20.9.2.5. The socket_instances Table

Instance tables document what types of objects are instrumented. They provide event names and explanatory notes or status information:

cond_instances: Condition synchronization object instances
file_instances: File instances
mutex_instances: Mutex synchronization object instances
rwlock_instances: Lock synchronization object instances
socket_instances: Active connection instances

These tables list instrumented synchronization objects, files, and connections. There are three types of synchronization objects: cond, mutex, and rwlock. Each instance table has an EVENT_NAME or NAME column to indicate the instrument associated with each row. Instrument names have multiple parts and form a hierarchy, as discussed in Section 20.4, "Performance Schema Instrument Naming Conventions".

The mutex_instances.LOCKED_BY_THREAD_ID and rwlock_instances.WRITE_LOCKED_BY_THREAD_ID columns are extremely important for investigating performance bottlenecks or deadlocks. For examples of how to use them for this purpose, see Section 20.15, "Using the Performance Schema to Diagnose Problems"