从字面意思看了一下是因为slave_pending_jobs_size_max默认值为16777216（16MB），但是slave接收到的slave_pending_jobs_size_max为17085453（17M）；
解决方案
从库执行如下SQL
mysql> stop slave; mysql>set global slave_pending_jobs_size_max=20000000; mysql> start slave;
#在多线程复制时，在队列中Pending的事件所占用的最大内存，默认为16M，如果内存富余，或者延迟较大时，可以适当调大;注意这个值要比主库的max_allowed_packet大
故障模拟：
从库设置：
mysql> set global slave_parallel_workers=4; mysql> show variables like 'slave_parallel_workers'; +------------------------+-------+ | Variable_name | Value | +------------------------+-------+ | slave_parallel_workers | 4 | +------------------------+-------+ 1 row in set (0.00 sec) <pre class="sql" name="code"> mysql> set global slave_pending_jobs_size_max=1024; mysql> show variables like 'slave_pend%'; +-----------------------------+-------+ | Variable_name | Value | +-----------------------------+-------+ | slave_pending_jobs_size_max | 1024 | +-----------------------------+-------+ 1 row in set (0.00 sec)
主库操作：
mysql> begin;
Query OK, 0 rows affected (0.00 sec)
mysql> update erp_mkpf set usnam='测试1864错误';
ERROR 1197 (HY000): Multi-statement transaction required more than 'max_binlog_cache_size' bytes of storage; increase this mysqld variable and try again mysql> set global max_binlog_cache_size=8388608000000;
Query OK, 0 rows affected (0.00 sec) mysql> begin;
Query OK, 0 rows affected (0.00 sec) mysql> update erp_mkpf set usnam='测试1864错误';
Query OK, 70466 rows affected (0.38 sec)
Rows matched: 70466 Changed: 70466 Warnings: 0 mysql> commit;
Query OK, 0 rows affected (0.08 sec)
从库查看状态：
mysql> show slave status\G
Last_SQL_Errno: 1864
Last_SQL_Error: Cannot schedule event Update_rows, relay-log name ./HE1-relay-bin.000005, position 494 to Worker thread because its size 8200 exceeds 1024 of slave_pending_jobs_size_max.