简单记录如下： 双主情况下跳过相同server id Event的方式： - IO线程 通过对比SERVER_ID 进行跳过操作 ``` { mi->set_master_log_pos(mi->get_master_log_pos() + inc_pos); memcpy(rli->ign_master_log_name_end, mi->get_master_log_name(), FN_REFLEN); DBUG_ASSERT(rli->ign_master_log_name_end[0]); rli->ign_master_log_pos_end= mi->get_master_log_pos(); } ``` - SQL线程构造一个Rotate_log_event ``` if (rli->ign_master_log_name_end[0]) { /* We generate and return a Rotate, to make our positions advance */ DBUG_PRINT("info",("seeing an ignored end segment")); ev= new Rotate_log_event(rli->ign_master_log_name_end, 0, rli->ign_master_log_pos_end, exec_relay_log_event Rotate_log_event::DUP_NAME); rli->ign_master_log_name_end[0]= 0; mysql_mutex_unlock(log_lock);exec_relay_log_event if (unlikely(!ev)) { errmsg= "Slave SQL thread failed to create a Rotate event " "(out of memory?), SHOW SLAVE STATUS may be inaccurate"; goto err; } ev->server_id= 0; // don't be ignored by slave SQL thread DBUG_RETURN(ev); } ``` 这样这些Event不会写入到relay log，SQL线程也不会读取，同时pos 也会做相应的增加。 欢迎关注我的《深入理解MySQL主从原理 32讲 》，如下：  如果图片不能显示可查看下面链接： https://www.jianshu.com/p/d636215d767f