master：安装半同步插件
(system@localhost) [(none)]> install plugin rpl_semi_sync_master soname 'semisync_master.so';
Query OK, 0 rows affected (0.83 sec)
(system@localhost) [(none)]> show plugins;
+----------------------------+----------+--------------------+--------------------+---------+
| Name | Status | Type | Library | License |
+----------------------------+----------+--------------------+--------------------+---------+
| binlog | ACTIVE | STORAGE ENGINE | NULL | GPL |
| mysql_native_password | ACTIVE | AUTHENTICATION | NULL | GPL |
| mysql_old_password | ACTIVE | AUTHENTICATION | NULL | GPL |
| sha256_password | ACTIVE | AUTHENTICATION | NULL | GPL |
| MRG_MYISAM | ACTIVE | STORAGE ENGINE | NULL | GPL |
。。。。。。。。。。。。。
| partition | ACTIVE | STORAGE ENGINE | NULL | GPL |
| rpl_semi_sync_master | ACTIVE | REPLICATION | semisync_master.so | GPL |
+----------------------------+----------+--------------------+--------------------+---------+
43 rows in set (0.00 sec)
启用主库半同步，并设置等待slave响应时间，单位秒
(system@localhost) [(none)]> set global rpl_semi_sync_master_enabled=1;
Query OK, 0 rows affected (0.00 sec)
(system@localhost) [(none)]> set global rpl_semi_sync_master_timeout=3000;
Query OK, 0 rows affected (0.00 sec)
slave:加载半同步插件
(system@localhost) [(none)]> install plugin rpl_semi_sync_slave soname 'semisync_slave.so';
Query OK, 0 rows affected (0.30 sec)
(system@localhost) [(none)]> show plugins;
+----------------------------+----------+--------------------+-------------------+---------+
| Name | Status | Type | Library | License |
+----------------------------+----------+--------------------+-------------------+---------+
| binlog | ACTIVE | STORAGE ENGINE | NULL | GPL |
| mysql_native_password | ACTIVE | AUTHENTICATION | NULL | GPL |
| mysql_old_password | ACTIVE | AUTHENTICATION | NULL | GPL |
。。。。。。。。。。。
| ARCHIVE | ACTIVE | STORAGE ENGINE | NULL | GPL |
| partition | ACTIVE | STORAGE ENGINE | NULL | GPL |
| rpl_semi_sync_slave | ACTIVE | REPLICATION | semisync_slave.so | GPL |
+----------------------------+----------+--------------------+-------------------+---------+
43 rows in set (0.13 sec)
从库开启半同步
(system@localhost) [(none)]> set global rpl_semi_sync_slave_enabled=1;
Query OK, 0 rows affected (0.03 sec)
这一步主要是为了让slave重连master节点，注册成为半同步身份，不重启则一直保持异步复制。
(system@localhost) [(none)]> stop slave io_thread;
Query OK, 0 rows affected (0.06 sec)
(system@localhost) [(none)]> start slave io_thread;
Query OK, 0 rows affected (0.02 sec)
(system@localhost) [(none)]> show status;
+-----------------------------------------------+---------------------+
| Variable_name | Value |
+-----------------------------------------------+---------------------+
| Aborted_clients | 0 |
| Aborted_connects | 0 |
。。。。。。。。。。。。。。
| Rpl_semi_sync_slave_status | ON |
。。。。。。。。。。
master：查看插件是否加载，开启半同步
(system@localhost) [(none)]> show status like 'rpl_semi_sync%';
+--------------------------------------------+-------+
| Variable_name | Value |
+--------------------------------------------+-------+
| Rpl_semi_sync_master_clients | 1 |
| Rpl_semi_sync_master_net_avg_wait_time | 0 |
| Rpl_semi_sync_master_net_wait_time | 0 |
| Rpl_semi_sync_master_net_waits | 0 |
| Rpl_semi_sync_master