In MySQL 8.0.14 and higher, the thread pool monitoring tables are Performance Schema tables that are loaded and unloaded along with the thread pool plugin. The INFORMATION_SCHEMA versions of the tables are deprecated but still available; they are installed per the instructions in Thread Pool Installation Prior to MySQL 8.0.14.

To enable thread pool capability, load the plugin by starting the server with the --plugin-load-add option. To do this, put these lines in the server my.cnf file, adjusting the .so suffix for your platform as necessary:

[mysqld]
plugin-load-add=thread_pool.so

To verify plugin installation, examine the Information Schema PLUGINS table or use the SHOW PLUGINS statement (see Section 7.6.2, “Obtaining Server Plugin Information”). For example:

mysql> SELECT PLUGIN_NAME, PLUGIN_STATUS
       FROM INFORMATION_SCHEMA.PLUGINS
       WHERE PLUGIN_NAME LIKE 'thread%';
+-----------------------+---------------+
| PLUGIN_NAME           | PLUGIN_STATUS |
+-----------------------+---------------+
| thread_pool           | ACTIVE        |
+-----------------------+---------------+

To verify that the Performance Schema monitoring tables are available, examine the Information Schema TABLES table or use the SHOW TABLES statement. For example:

mysql> SELECT TABLE_NAME
       FROM INFORMATION_SCHEMA.TABLES
       WHERE TABLE_SCHEMA = 'performance_schema'
       AND TABLE_NAME LIKE 'tp%';
+-----------------------+
| TABLE_NAME            |
+-----------------------+
| tp_thread_group_state |
| tp_thread_group_stats |
| tp_thread_state       |
+-----------------------+

If the server loads the thread pool plugin successfully, it sets the thread_handling system variable to loaded-dynamically.

If the plugin fails to initialize, check the server error log for diagnostic messages.

Prior to MySQL 8.0.14, the thread pool monitoring tables are plugins separate from the thread pool plugin and can be installed separately.

To enable thread pool capability, load the plugins to be used by starting the server with the --plugin-load-add option. For example, if you name only the plugin library file, the server loads all plugins that it contains (that is, the thread pool plugin and all the INFORMATION_SCHEMA tables). To do this, put these lines in the server my.cnf file, adjusting the .so suffix for your platform as necessary:

[mysqld]
plugin-load-add=thread_pool.so

That is equivalent to loading all thread pool plugins by naming them individually:

[mysqld]
plugin-load-add=thread_pool=thread_pool.so
plugin-load-add=tp_thread_state=thread_pool.so
plugin-load-add=tp_thread_group_state=thread_pool.so
plugin-load-add=tp_thread_group_stats=thread_pool.so

If desired, you can load individual plugins from the library file. To load the thread pool plugin but not the INFORMATION_SCHEMA tables, use an option like this:

[mysqld]
plugin-load-add=thread_pool=thread_pool.so

To load the thread pool plugin and only the TP_THREAD_STATE INFORMATION_SCHEMA table, use options like this:

[mysqld]
plugin-load-add=thread_pool=thread_pool.so
plugin-load-add=tp_thread_state=thread_pool.so

To verify plugin installation, examine the Information Schema PLUGINS table or use the SHOW PLUGINS statement (see Section 7.6.2, “Obtaining Server Plugin Information”). For example:

mysql> SELECT PLUGIN_NAME, PLUGIN_STATUS
       FROM INFORMATION_SCHEMA.PLUGINS
       WHERE PLUGIN_NAME LIKE 'thread%' OR PLUGIN_NAME LIKE 'tp%';
+-----------------------+---------------+
| PLUGIN_NAME           | PLUGIN_STATUS |
+-----------------------+---------------+
| thread_pool           | ACTIVE        |
| TP_THREAD_STATE       | ACTIVE        |
| TP_THREAD_GROUP_STATE | ACTIVE        |
| TP_THREAD_GROUP_STATS | ACTIVE        |
+-----------------------+---------------+

If the server loads the thread pool plugin successfully, it sets the thread_handling system variable to loaded-dynamically.

If a plugin fails to initialize, check the server error log for diagnostic messages.