Master-Slave Semisynchronous Replication on MySQL 5.7.13

Prerequisites

1. 检查 have_dynamic_loading 系统变量值为 YES。
2. 复制已经在正常运行。
3. 不能配置多复制通道，半同步复制只能兼容默认的复制通道。

Procedure

1. 检查动态加载插件要求。

   mysql> show variables like 'have_dynamic_loading';
   +----------------------+-------+
   | Variable_name        | Value |
   +----------------------+-------+
   | have_dynamic_loading | YES   |
   +----------------------+-------+
   1 row in set (0.02 sec)

2. 安装插件。

   源端

   mysql> INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so';
   Query OK, 0 rows affected (0.15 sec)
   
   mysql> SELECT PLUGIN_NAME, PLUGIN_STATUS
       -> FROM INFORMATION_SCHEMA.PLUGINS
       -> WHERE PLUGIN_NAME LIKE '%semi%';
   +----------------------+---------------+
   | PLUGIN_NAME          | PLUGIN_STATUS |
   +----------------------+---------------+
   | rpl_semi_sync_master | ACTIVE        |
   +----------------------+---------------+
   1 row in set (0.00 sec)

   复制端

   mysql> INSTALL PLUGIN rpl_semi_sync_slave SONAME 'semisync_slave.so';
   Query OK, 0 rows affected (0.19 sec)
   
   mysql> SELECT PLUGIN_NAME, PLUGIN_STATUS
       -> FROM INFORMATION_SCHEMA.PLUGINS
       -> WHERE PLUGIN_NAME LIKE '%semi%';
   +---------------------+---------------+
   | PLUGIN_NAME         | PLUGIN_STATUS |
   +---------------------+---------------+
   | rpl_semi_sync_slave | ACTIVE        |
   +---------------------+---------------+
   1 row in set (0.00 sec)

3. 配置系统变量。

   源端

   SET GLOBAL rpl_semi_sync_master_enabled = {0|1};
   SET GLOBAL rpl_semi_sync_master_timeout = N;

   [mysqld]
   rpl_semi_sync_master_enabled=1
   rpl_semi_sync_master_timeout=1000 # 1 second

   复制端

   SET GLOBAL rpl_semi_sync_slave_enabled = {0|1};

   [mysqld]
   rpl_semi_sync_slave_enabled=1

4. 重启复制 IO 线程。

   stop slave io_thread;
   start slave io_thread;