Information Schema THREAD_POOL_QUEUES Table

The Information Schema THREAD_POOL_QUEUES table shows the status of the queues within the thread pool, detailing pending connections.

This table is available from MariaDB 10.5.

The table provides information about thread pool queues, and contains the following columns:

Column	Description
GROUP_ID	the thread group this row is showing data for
POSITION	position in the groups queue
PRIORITY	request priority, see priority scheduling
CONNECTION_ID	ID of the client connection that submitted the queued request
QUEUEING_TIME_MICROSECONDS	how long the request has already been waiting in the queue in microseconds

Setting thread_poll_exact_stats will provides better queueing time statistics by using a high precision timestamp, at a small performance cost, for the time when the connection was added to the queue. This timestamp helps calculate the queuing time shown in the table.

Setting thread_pool_dedicated_listener will give each group its own dedicated listener, and the listener thread will not pick up work items. As a result, the queueing time in the table will be more exact, since IO requests are immediately dequeued from poll, without delay.

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