• 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 may have multiple parts and form a hierarchy, as discussed in Section 27.6, “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 27.19, “Using the Performance Schema to Diagnose Problems” 

## 27.12.3.1 The cond_instances Table 

The cond_instances  table lists all the conditions seen by the Performance Schema while the server executes. A condition is a synchronization mechanism used in the code to signal that a specific event has happened, so that a thread waiting for this condition can resume work. 

When a thread is waiting for something to happen, the condition name is an indication of what the thread is waiting for, but there is no immediate way to tell which other thread, or threads, causes the condition to happen. 

## 27.12.3.2 The file_instances Table 

The cond_instances  table has these columns: 

• NAME 

The instrument name associated with the condition. 

• OBJECT_INSTANCE_BEGIN 

The address in memory of the instrumented condition. 

The cond_instances  table has these indexes: 

•Primary key on ( OBJECT_INSTANCE_BEGIN ) 

•Index on ( NAME ) 

TRUNCATE TABLE  is not permitted for the cond_instances  table. 

The file_instances  table lists all the files seen by the Performance Schema when executing file I/O instrumentation. If a file on disk has never been opened, it is not shown in file_instances . When a file is deleted from the disk, it is also removed from the file_instances  table. 

The file_instances  table has these columns: 

• FILE_NAME 

