THREAD_POOL_STATS
This page is part of MariaDB's Documentation.
The parent of this page is: Information Schema for MariaDB Enterprise Server
Topics on this page:
Overview
DETAILS
SCHEMA
CREATE TEMPORARY TABLE `THREAD_POOL_STATS` (
`GROUP_ID` int(6) NOT NULL,
`THREAD_CREATIONS` bigint(19) NOT NULL,
`THREAD_CREATIONS_DUE_TO_STALL` bigint(19) NOT NULL,
`WAKES` bigint(19) NOT NULL,
`WAKES_DUE_TO_STALL` bigint(19) NOT NULL,
`THROTTLES` bigint(19) NOT NULL,
`STALLS` bigint(19) NOT NULL,
`POLLS_BY_LISTENER` bigint(19) NOT NULL,
`POLLS_BY_WORKER` bigint(19) NOT NULL,
`DEQUEUES_BY_LISTENER` bigint(19) NOT NULL,
`DEQUEUES_BY_WORKER` bigint(19) NOT NULL
)
Column Descriptions
Variable | Description |
|---|---|
GROUP_ | ID of the group this row is for |
THREAD_ | The number of threads created for this group so far |
THREAD_ | How often a thread was created as another one was identified as stalled |
WAKES | How often a standby thread has been woken up |
WAKES_ | How often standby thread wakeup was due to another thread having been found to be stalled |
THROTTLES | How often thread creation was throttled |
STALLS | How often a stalled thread was detected |
POLLS_ | The number of network "polls" done by the listener thread. The "poll" a name of OS dependent efficient system call to pick up readable sockets - in context of MariaDB, readable socket means client sent a request, which was not handled yet. |
POLLS_ | If queue is empty, a worker thread might try a non-blocking "poll" (see previous section for description) before going to sleep. The number of those "polls" is this value. |
DEQUEUES_ | The number of dequeues, done by listener thread. Recall that each group has a queue, and the operation of removing entry from this queue is called a "dequeue" . Usually, listener thread populates (enqueues works to) that queue, and workers dequeue and handle request, but if the load is light, it is more efficient if listener both polls and handles the work, as it saves on inter-thread communication. If thread_ |
DEQUEUES_ | The number of dequeue operations (see previous section for explanation) done by worker threads. |