# Replica SQL Thread States

This article documents thread states that are related to [replication](https://mariadb.com/docs/server/ha-and-performance/standard-replication/replication-overview) slave SQL threads. These correspond to the `Slave_SQL_State` shown by [SHOW SLAVE STATUS](https://mariadb.com/docs/server/reference/sql-statements/administrative-sql-statements/show/show-replica-status) as well as the `STATE` values listed by the [SHOW PROCESSLIST](https://mariadb.com/docs/server/reference/sql-statements/administrative-sql-statements/show/show-processlist) statement and the [Information Schema PROCESSLIST](https://mariadb.com/docs/server/reference/system-tables/information-schema/information-schema-tables/information-schema-processlist-table) as well as the `PROCESSLIST_STATE` value listed in the [Performance Schema threads Table](https://mariadb.com/docs/server/reference/system-tables/performance-schema/performance-schema-tables/performance-schema-threads-table).

| Value                                                                                       | Description                                                                                                                                                                                                                                     |
| ------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Apply log event                                                                             | Log event is being applied.                                                                                                                                                                                                                     |
| Making temp file                                                                            | Creating a temporary file containing the row data as part of a [LOAD DATA INFILE](https://mariadb.com/docs/server/reference/sql-statements/data-manipulation/inserting-loading-data/load-data-into-tables-or-index/load-data-infile) statement. |
| Reading event from the relay log                                                            | Reading an event from the [relay log](https://mariadb.com/docs/server/server-management/server-monitoring-logs/binary-log/relay-log) in order to process the event.                                                                             |
| Slave has read all relay log, waiting for the slave I/O thread to update it                 | All [relay log](https://mariadb.com/docs/server/server-management/server-monitoring-logs/binary-log/relay-log) events have been processed, now waiting for the I/O thread to write new events to the relay log.                                 |
| Waiting for work from SQL thread                                                            | In parallel replication the worker thread is waiting for more things from the SQL thread.                                                                                                                                                       |
| Waiting for prior transaction to start commit before starting next transaction              | In parallel replication the worker thread is waiting for conflicting things to end before starting executing.                                                                                                                                   |
| Waiting for worker threads to be idle                                                       | Happens in parallel replication when moving to a new binary log after a master restart. All slave temporary files are deleted, and worker threads are restarted.                                                                                |
| Waiting due to global read lock                                                             | In parallel replication when worker threads are waiting for a global read lock to be released.                                                                                                                                                  |
| Waiting for worker threads to pause for global read lock                                    | [FLUSH TABLES WITH READ LOCK](https://mariadb.com/docs/server/reference/sql-statements/administrative-sql-statements/flush-commands/flush) is waiting for worker threads to finish what they are doing.                                         |
| Waiting while replication worker thread pool is busy                                        | Happens in parallel replication during a [FLUSH TABLES WITH READ LOCK](https://mariadb.com/docs/server/reference/sql-statements/administrative-sql-statements/flush-commands/flush) or when changing number of parallel workers.                |
| Waiting for other master connection to process GTID received on multiple master connections | A worker thread noticed that there is already another thread executing the same GTID from another connection and it's waiting for the other to complete.                                                                                        |
| Waiting for slave mutex on exit                                                             | Thread is stopping. Only occurs very briefly.                                                                                                                                                                                                   |
| Waiting for the next event in relay log                                                     | State before reading next event from the [relay log](https://mariadb.com/docs/server/server-management/server-monitoring-logs/binary-log/relay-log).                                                                                            |

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