Multi-threaded Replication - Only One Thread Works At A Time?
(Doc ID 1580190.1)
Last updated on MARCH 21, 2022
Applies to:
MySQL Server - Version 5.6 to 5.7 [Release 5.6 to 5.7]Information in this document applies to any platform.
Symptoms
Even though Multi Threaded Secondary (MTS) is enabled, all the secondary worker threads do not work in parallel :
mysql> select * from mysql.slave_worker_info;
+----+---------------------------------------+---------------+------------------+----------------+-----------------------------------+--------------------------+----------------------------+---------------------------+------------------+
| Id | Relay_log_name | Relay_log_pos | Master_log_name | Master_log_pos | Checkpoint_relay_log_name | Checkpoint_relay_log_pos | Checkpoint_master_log_name | Checkpoint_master_log_pos | Checkpoint_seqno |
+----+---------------------------------------+---------------+------------------+----------------+-----------------------------------+--------------------------+----------------------------+---------------------------+------------------+
| 1 | | 0 | | 0 | | 0 | | 0 | 0 |
| 2 | | 0 | | 0 | | 0 | | 0 | 0 |
| 3 | | 0 | | 0 | | 0 | | 0 | 0 |
| 4 | | 0 | | 0 | | 0 | | 0 | 0 |
| 5 | /data/relay_logs/relay-bin.000791 | 132586803 | mysql-bin.029988 | 132586640 | /data/relay_logs/relay-bin.000791 | 132477675 | mysql-bin.029988 | 132477512 | 34 |
| 6 | /data/relay_logs/relay-bin.000791 | 346324121 | mysql-bin.029988 | 346323958 | /data/relay_logs/relay-bin.000791 | 343332091 | mysql-bin.029988 | 343331928 | 25 |
| 7 | /data/relay_logs/relay-bin.000791 | 343589778 | mysql-bin.029988 | 343589615 | /data/relay_logs/relay-bin.000791 | 343332091 | mysql-bin.029988 | 343331928 | 18 |
| 8 | /data/relay_logs/relay-bin.000791 | 348763028 | mysql-bin.029988 | 348762865 | /data/relay_logs/relay-bin.000791 | 346341703 | mysql-bin.029988 | 346341540 | 23 |
+----+-----------------------------------+---------------+------------------+----------------+------------------------------------+--------------------------+----------------------------+---------------------------+------------------+
8 rows in set (0.00 sec)
Changes
Multi Thread Secondary has been enabled with below settings in my.cnf file:
Cause
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In this Document
| Symptoms |
| Changes |
| Cause |
| Solution |
| References |