0.安装配置replication（略）
1.On Master:mysql> INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so';
2. On Slave:mysql> INSTALL PLUGIN rpl_semi_sync_slave SONAME 'semisync_slave.so';
3.master: mysql> SET GLOBAL rpl_semi_sync_master_enabled = 1;
slave: SET GLOBAL rpl_semi_sync_slave_enabled = 1;`
mysql> stop slave io_thread;
mysql> start slave io_thread;
４. 几个监控命令：
mysql> SHOW STATUS LIKE 'Rpl_semi_sync%';
mysql> SHOW variables LIKE '%sync%';
mysql> show plugins;
