半同步复制支持多种插件：/usr/lib64/mysql/plugin/*
[root@localhost ~]# rpm -ql mariadb-server | grep semisync
/usr/lib64/mysql/plugin/semisync_master.so
/usr/lib64/mysql/plugin/semisync_slave.so
半同步复制插件：
semisync_master.so
semisync_slave.so
查看插件是否安装：
MariaDB [(none)]> SHOW PLUGINS;
+--------------------------------+----------+--------------------+---------+---------+
| Name | Status | Type | Library | License |
+--------------------------------+----------+--------------------+---------+---------+
在主节点安装并启用插件：
MariaDB [(none)]> INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so';
Query OK, 0 rows affected (0.00 sec)
MariaDB [(none)]> SHOW PLUGINS;
+--------------------------------+----------+--------------------+--------------------+---------+
| Name | Status | Type | Library | License |
+--------------------------------+----------+--------------------+--------------------+---------+
| binlog | ACTIVE | STORAGE ENGINE | NULL
MariaDB [(none)]> SHOW GLOBAL VARIABLES LIKE '%semi%';
+------------------------------------+-------+
| Variable_name | Value |
+------------------------------------+-------+
| rpl_semi_sync_master_enabled | OFF |
| rpl_semi_sync_master_timeout | 10000 |
| rpl_semi_sync_master_trace_level | 32 |
| rpl_semi_sync_master_wait_no_slave | ON |
+------------------------------------+-------+
4 rows in set (0.00 sec)
MariaDB [(none)]> SET @@global.rpl_semi_sync_master_enabled=ON;
Query OK, 0 rows affected (0.00 sec)
MariaDB [(none)]> SHOW GLOBAL VARIABLES LIKE '%semi%';
+------------------------------------+-------+
| Variable_name | Value |
+------------------------------------+-------+
| rpl_semi_sync_master_enabled | ON |
| rpl_semi_sync_master_timeout | 10000 |
| rpl_semi_sync_master_trace_level | 32 |
| rpl_semi_sync_master_wait_no_slave | ON |
+------------------------------------+-------+
4 rows in set (0.00 sec)
在从节点安装并启用插件：
MariaDB [(none)]> INSTALL PLUGIN rpl_semi_sync_slave SONAME 'semisync_slave.so';
Query OK, 0 rows affected (0.00 sec)
MariaDB [(none)]> SHOW PLUGINS;
+--------------------------------+----------+--------------------+-------------------+---------+
| Name | Status | Type | Library | License |
+--------------------------------+----------+--------------------+-------------------+---------+
| binlog | ACTIVE | STORAGE ENGINE | NULL
MariaDB [(none)]> SHOW GLOBAL VARIABLES LIKE '%semi%';
+---------------------------------+-------+
| Variable_name | Value |
+---------------------------------+-------+
| rpl_semi_sync_slave_enabled | OFF |
| rpl_semi_sync_slave_trace_level | 32 |
+---------------------------------+-------+
2 rows in set (0.00 sec)
MariaDB [(none)]> SET @@global.rpl_semi_sync_slave_enabled=ON;
Query OK, 0 rows affected (0.00 sec)
MariaDB [(none)]> SHOW GLOBAL VARIABLES LIKE '%semi%';
+---------------------------------+-------+
| Variable_name | Value |
+---------------------------------+-------+
| rpl_semi_sync_slave_enabled | ON |
| rpl_semi_sync_slave_trace_level | 32 |
+---------------------------------+-------+
2 rows in set (0.00 sec)
主节点：
MariaDB [(none)]> SHOW GLOBAL STATUS LIKE '%semi%';
+--------------------------------------------+-------+
| Variable_name | Value |
+--------------------------------------------+-------+
| Rpl_semi_sync_master_clients | 0 |
| 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_no_times | 0 |
| Rpl_semi_sync_master_no_tx | 0 |
| Rpl_semi_sync_master_status | ON |
| Rpl_semi_sync_master_timefunc_failures | 0 |
| Rpl_semi_sync_master_tx_avg_wait_time | 0 |
| Rpl_semi_sync_master_tx_wait_time | 0 |
| Rpl_semi_sync_master_tx_waits | 0 |
| Rpl_semi_sync_master_wait_pos_backtraverse | 0 |
| Rpl_semi_sync_master_wait_sessions | 0 |
| Rpl_semi_sync_master_yes_tx | 0 |
+--------------------------------------------+-------+
14 rows in set (0.00 sec)
从节点启动IO线程：
MariaDB [(none)]> STOP SLAVE IO_THREAD;
Query OK, 0 rows affected (0.00 sec)
MariaDB [(none)]> START SLAVE IO_THREAD;
Query OK, 0 rows affected (0.00 sec)
主节点：
MariaDB [(none)]> SHOW GLOBAL STATUS LIKE '%semi%';
+--------------------------------------------+-------+
| 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_no_times | 0 |
| Rpl_semi_sync_master_no_tx | 0 |
| Rpl_semi_sync_master_status | ON |
| Rpl_semi_sync_master_timefunc_failures | 0 |
| Rpl_semi_sync_master_tx_avg_wait_time | 0 |
| Rpl_semi_sync_master_tx_wait_time | 0 |
| Rpl_semi_sync_master_tx_waits | 0 |
| Rpl_semi_sync_master_wait_pos_backtraverse | 0 |
| Rpl_semi_sync_master_wait_sessions | 0 |
| Rpl_semi_sync_master_yes_tx | 0 |
+--------------------------------------------+-------+
14 rows in set (0.00 sec)
在主节点为事先创建的用户进行主从复制授权：
MariaDB [(none)]> grant replication slave on *.* to 'myslave'@'192.168.200.%' identified by '123456';
Query OK, 0 rows affected (0.00 sec)
MariaDB [(none)]> flush privileges;
Query OK, 0 rows affected (0.00 sec)
MariaDB [(none)]> show master status;
+---------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+---------------------+----------+--------------+------------------+
| mysql-binlog.000003 | 487 | | |
+---------------------+----------+--------------+------------------+
1 row in set (0.00 sec)
从节点：
MariaDB [(none)]> CHANGE MASTER TO
-> MASTER_HOST='192.168.200.113',
-> MASTER_USER='myslave',
-> MASTER_PASSWORD='123456',
-> MASTER_LOG_FILE='mysql-binlog.000003',
-> MASTER_LOG_POS=487;
Query OK, 0 rows affected (0.02 sec)
MariaDB [(none)]> start slave;
Query OK, 0 rows affected (0.00 sec)
在主节点创建数据库mydb：
MariaDB [(none)]> CREATE DATABASE mydb CHARACTER SET 'utf8';
Query OK, 1 row affected (0.00 sec)
MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mydb |
| mysql |
| performance_schema |
| test |
+--------------------+
5 rows in set (0.00 sec)
从节点查看数据库是否复制成功：
MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mydb |
| mysql |
| performance_schema |
| test |
+--------------------+
5 rows in set (0.00 sec)
发现数据库mydb成功复制
使用数据库mydb在主节点进行数据操作：
MariaDB [(none)]> use mydb;
Database changed
MariaDB [mydb]> CREATE TABLE tbl1 (id INT,name VARCHAR(100));
Query OK, 0 rows affected (0.01 sec)
在主节点上观察：
MariaDB [mydb]> SHOW GLOBAL STATUS LIKE '%semi%';
+--------------------------------------------+-------+
| Variable_name | Value |
+--------------------------------------------+-------+
| Rpl_semi_sync_master_clients | 1 |
| Rpl_semi_sync_master_net_avg_wait_time | 734 |
| Rpl_semi_sync_master_net_wait_time | 1469 |
| Rpl_semi_sync_master_net_waits | 2 |
| Rpl_semi_sync_master_no_times | 0 |
| Rpl_semi_sync_master_no_tx | 0 |
| Rpl_semi_sync_master_status | ON |
| Rpl_semi_sync_master_timefunc_failures | 0 |
| Rpl_semi_sync_master_tx_avg_wait_time | 902 |
| Rpl_semi_sync_master_tx_wait_time | 1804 |
| Rpl_semi_sync_master_tx_waits | 2 |
| Rpl_semi_sync_master_wait_pos_backtraverse | 0 |
| Rpl_semi_sync_master_wait_sessions | 0 |
| Rpl_semi_sync_master_yes_tx | 2 |
+--------------------------------------------+-------+
14 rows in set (0.00 sec)
主节点继续操作：
MariaDB [mydb]> INSERT INTO tbl1 VALUES (1,'tom');
Query OK, 1 row affected (0.01 sec)
我们发现从节点的数据都在变化：
MariaDB [mydb]> SHOW GLOBAL STATUS LIKE '%semi%';
+--------------------------------------------+-------+
| Variable_name | Value |
+--------------------------------------------+-------+
| Rpl_semi_sync_master_clients | 1 |
| Rpl_semi_sync_master_net_avg_wait_time | 1055 |
| Rpl_semi_sync_master_net_wait_time | 3166 |
| Rpl_semi_sync_master_net_waits | 3 |
| Rpl_semi_sync_master_no_times | 0 |
| Rpl_semi_sync_master_no_tx | 0 |
| Rpl_semi_sync_master_status | ON |
| Rpl_semi_sync_master_timefunc_failures | 0 |
| Rpl_semi_sync_master_tx_avg_wait_time | 1112 |
| Rpl_semi_sync_master_tx_wait_time | 3338 |
| Rpl_semi_sync_master_tx_waits | 3 |
| Rpl_semi_sync_master_wait_pos_backtraverse | 0 |
| Rpl_semi_sync_master_wait_sessions | 0 |
| Rpl_semi_sync_master_yes_tx | 3 |
+--------------------------------------------+-------+
14 rows in set (0.00 sec)