29.12.16 Performance Schema Thread Pool Tables (original) (raw)

29.12.16 Performance Schema Thread Pool Tables

The following sections describe the Performance Schema tables associated with the thread pool plugin (seeSection 7.6.3, “MySQL Enterprise Thread Pool”). They provide information about thread pool operation:

• tp_connections: Information about thread pool connections.
• tp_thread_group_state: Information about thread pool thread group states.
• tp_thread_group_stats: Thread group statistics.
• tp_thread_state: Information about thread pool thread states.

Rows in these tables represent snapshots in time. In the case oftp_thread_state, all rows for a thread group comprise a snapshot in time. Thus, the MySQL server holds the mutex of the thread group while producing the snapshot. But it does not hold mutexes on all thread groups at the same time, to prevent a statement againsttp_thread_state from blocking the entire MySQL server.

The Performance Schema thread pool tables are implemented by the thread pool plugin and are loaded and unloaded when that plugin is loaded and unloaded (seeSection 7.6.3.2, “Thread Pool Installation”). No special configuration step for the tables is needed. However, the tables depend on the thread pool plugin being enabled. If the thread pool plugin is loaded but disabled, the tables are not created.