8.14.5 Replication Slave SQL Thread States

Killing slave

The thread is processing a STOP SLAVE statement.

Making temporary file (append) before replaying LOAD DATA INFILE

The thread is executing a LOAD DATA statement and is appending the data to a temporary file containing the data from which the slave will read rows.

Making temporary file (create) before replaying LOAD DATA INFILE

The thread is executing a LOAD DATA statement and is creating a temporary file containing the data from which the slave will read rows. This state can only be encountered if the original LOAD DATA statement was logged by a master running a version of MySQL lower than MySQL 5.0.3.

Reading event from the relay log

The thread has read an event from the relay log so that the event can be processed.

Slave has read all relay log; waiting for more updates

The thread has processed all events in the relay log files, and is now waiting for the I/O thread to write new events to the relay log.

Waiting for an event from Coordinator

Using the multithreaded slave (slave_parallel_workers is greater than 1), one of the slave worker threads is waiting for an event from the coordinator thread.

Waiting for slave mutex on exit

A very brief state that occurs as the thread is stopping.

Waiting for Slave Workers to free pending events

This waiting action occurs when the total size of events being processed by Workers exceeds the size of the slave_pending_jobs_size_max system variable. The Coordinator resumes scheduling when the size drops below this limit. This state occurs only when slave_parallel_workers is set greater than 0.

Waiting for the next event in relay log

The initial state before Reading event from the relay log.

Waiting until MASTER_DELAY seconds after master executed event

The SQL thread has read an event but is waiting for the slave delay to lapse. This delay is set with the MASTER_DELAY option of CHANGE MASTER TO.