The thread pool feature comprises these components:
A plugin library file contains a plugin for the thread pool
code and plugins for several
INFORMATION_SCHEMA tables.
For a detailed description of how the thread pool works, see Section 5.5.4.3, “Thread Pool Operation”.
The INFORMATION_SCHEMA tables are named
TP_THREAD_STATE,
TP_THREAD_GROUP_STATE, and
TP_THREAD_GROUP_STATS. These
tables provide information about thread pool operation. For
more information, see
Section 21.30, “Thread Pool INFORMATION_SCHEMA Tables”.
Several system variables are related to the thread pool. The
thread_handling system
variable has a value of
loaded-dynamically when the server
successfully loads the thread pool plugin.
The other related variables are implemented by the thread pool plugin; they are not available unless it is enabled:
thread_pool_algorithm:
The concurrency algorithm to use for scheduling.
thread_pool_high_priority_connection:
How to schedule statement execution for a session.
thread_pool_prio_kickup_timer:
How long before the thread pool moves a statement
awaiting execution from the low-priority queue to the
high-priority queue.
thread_pool_max_unused_threads:
How many sleeping threads to permit.
thread_pool_size: The
number of thread groups in the thread pool. This is the
most important parameter controlling thread pool
performance.
thread_pool_stall_limit:
The time before an executing statement is considered to
be stalled.
If any variable implemented by the plugin is set to an illegal value at startup, plugin initialization fails and the plugin does not load.
For information about setting thread pool parameters, see Section 5.5.4.4, “Thread Pool Tuning”.
The Performance Schema exposes information about the thread pool and may be used to investigate operational performance. For more information, see Chapter 22, MySQL Performance Schema.