Performance Schema Instance Tables

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 , "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 , "Using the Performance Schema to Diagnose Problems"

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