生产排查 | MySQL主从同步时报错1864之slave_pending_jobs_size_max设置生产排查

本文链接：https://blog.youkuaiyun.com/db_murphy/article/details/117793524

大家都知道，MySQL 的各参数很多，设置不恰当，会引起各种异常；

本文根据一则实际生产异常场景，即从库的同步异常报错Last_Errno: 1864，来介绍slave_pending_jobs_size_max参数的调整。

问题现象描述

生产环境上从库出现SQL进程停止的异常，错误信息如下：

mysql> show slave status \G;                                                                                                                                                                 *************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.0.11
                  Master_User: replica_01
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.004783
          Read_Master_Log_Pos: 3681586
               Relay_Log_File: DB2-relay-bin.000007
                Relay_Log_Pos: 671091671
        Relay_Master_Log_File: mysql-bin.004782
             Slave_IO_Running: Yes
            Slave_SQL_Running: No
              Replicate_Do_DB: 
          Replicate_Ignore_DB: 
           Replicate_Do_Table: 
       Replicate_Ignore_Table: 
      Replicate_Wild_Do_Table: 
  Replicate_Wild_Ignore_Table: 
                   Last_Errno: 1864
                   Last_Error: Cannot schedule event Update_rows, relay-log name ./DB2-relay-bin.000007, position 671094876 to Worker thread because its size 50450016 exceeds 16777216 of slave_pending_jobs_size_max.
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 671091458