1.环境
| 主机 | master | slave |
| 版本 | 5.7.14 | 5.7.14 |
| ip | 192.168.26.233 | 192.168.26.108 |
| port | 3306 | 3306 |
1.安装相关的插件
show plugins; 查看模块
help --uninstall; 查看卸载模块
master插件安装 -- 安装 semisync_master.so插件
mysql>install plugin rpl_semi_sync_master soname 'semisync_master.so';
Query OK, 0 rows affected (0.03 sec)slave插件安装:- --安装 semisync_slave.so插件
root@localhost [zw3306]>install plugin rpl_semi_sync_slave soname 'semisync_slave.so';
Query OK, 0 rows affected (0.00 sec)
root@localhost [zw3306]>install plugin rpl_semi_sync_master soname 'semisync_master.so';
Query OK, 0 rows affected (0.00 sec)2.修改的参数：
set global rpl_semi_sync_master_enabled=1;
set global rpl_semi_sync_master_timeout=1000;
set global rpl_semi_sync_slave_enabled=1;也可以直接写到配置文件my.cnf
master:
[mysqld]
rpl_semi_sync_master_enabled = 1
rpl_semi_sync_master_timeout = 1000 # 1 second注：相关参数说明
rpl_semi_sync_master_timeout=milliseconds
设置此参数值（ms）,为了防止半同步复制在没有收到确认的情况下发生堵塞，如果Master在超时之前没有收到任何确认，将恢复到正常的异步复制，并继续执行没有半同步的复制操作。
rpl_semi_sync_master_wait_no_slave={ON|OFF}
如果一个事务被提交,但Master没有任何Slave的连接，这时不可能将事务发送到其它地方保护起来。默认情况下，Master会在时间限制范围内继续等待Slave的连接，并确认该事务已经被正确的写到磁盘上。
可以使用此参数选项关闭这种行为，在这种情况下，如果没有Slave连接，Master就会恢复到异步复制。
slave：
[mysqld]
rpl_semi_sync_slave_enabled = 1修改了参数需要重启：
查看修改的参数
master:
mysql> show global variables like '%rpl_semi%';
+-------------------------------------------+------------+
| Variable_name | Value |
+-------------------------------------------+------------+
| rpl_semi_sync_master_enabled | ON |
| rpl_semi_sync_master_timeout | 1000 |
| rpl_semi_sync_master_trace_level | 32 |
| rpl_semi_sync_master_wait_for_slave_count | 1 |
| rpl_semi_sync_master_wait_no_slave | ON |
| rpl_semi_sync_master_wait_point | AFTER_SYNC |
+-------------------------------------------+------------+
6 rows in set (0.00 sec)
slave:
root@localhost [(none)]>show global variables like '%rpl_semi%';
+-------------------------------------------+------------+
| Variable_name | Value |
+-------------------------------------------+------------+
| rpl_semi_sync_master_enabled | ON |
| rpl_semi_sync_master_timeout | 1000 |
| rpl_semi_sync_master_trace_level | 32 |
| rpl_semi_sync_master_wait_for_slave_count | 1 |
| rpl_semi_sync_master_wait_no_slave | ON |
| rpl_semi_sync_master_wait_point | AFTER_SYNC |
| rpl_semi_sync_slave_enabled | ON |
| rpl_semi_sync_slave_trace_level | 32 |
+-------------------------------------------+------------+
8 rows in set (0.00 sec)
如果：如果原来是已经建好的复制结构很简单：
stop slave io_thread;
start slave io_thread;
3.做同步
change master to master_host='192.168.26.233', master_port=3306, master_user='repl',master_password='repl', master_auto_position=1;
root@localhost [(none)]>start slave;
Query OK, 0 rows affected (0.01 sec)
root@localhost [(none)]>show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.26.233
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000002
Read_Master_Log_Pos: 194
Relay_Log_File: relay-bin.000004
Relay_Log_Pos: 407
Relay_Master_Log_File: mysql-bin.000002
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 194
Relay_Log_Space: 861
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 3306100
Master_UUID: 7e354a2c-6f5f-11e6-997d-005056a36f08
Master_Info_File: mysql.slave_master_info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set: 7e354a2c-6f5f-11e6-997d-005056a36f08:1-9
Executed_Gtid_Set: 7e354a2c-6f5f-11e6-997d-005056a36f08:1-9,
ba0d5587-74d6-11e6-ab5c-005056a3f46e:1-2
Auto_Position: 1
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
1 row in set (0.00 sec)
ERROR:
No query specified
5.查看slave是否有数据
root@localhost [zw3306]>show tables;
+------------------+
| Tables_in_zw3306 |
+------------------+
| t1 |
+------------------+
1 row in set (0.00 sec)
root@localhost [zw3306]>select * from t1;
+------+
| id |
+------+
| 1 |
| 2 |
| 3 |
| 4 |
+------+
4 rows in set (0.00 sec)6. 怎么确认是同步还是半同步？
show global variables like '%semi%';
show global status like '%semi%';master:
root@localhost [zw3306]>show global status like '%semi%';
+--------------------------------------------+-------+
| Variable_name | Value |
+--------------------------------------------+-------+
| Rpl_semi_sync_master_clients | 1 | 有多少个Semi-sync的备库
| Rpl_semi_sync_master_net_avg_wait_time | 0 | 事务提交后，等待备库响应的平均时间
| Rpl_semi_sync_master_net_wait_time | 0 | 等待网络响应的总次数
| Rpl_semi_sync_master_net_waits | 7 | 总的网络等待时间
| Rpl_semi_sync_master_no_times | 0 | 一共有几次从Semi-sync跌回普通状态
| Rpl_semi_sync_master_no_tx | 0 | 库未及时响应的事务数,如果这个值很大就有问题
| Rpl_semi_sync_master_status | ON | 主库上Semi-sync是否正常开启
| Rpl_semi_sync_master_timefunc_failures | 0 | 时间函数未正常工作的次数
| Rpl_semi_sync_master_tx_avg_wait_time | 410 | 开启Semi-sync，事务返回需要等待的平均时间
| Rpl_semi_sync_master_tx_wait_time | 2876 | 事务等待备库响应的总时间
| Rpl_semi_sync_master_tx_waits | 7 | 事务等待备库响应的总次数
| Rpl_semi_sync_master_wait_pos_backtraverse | 0 | 改变当前等待最小二进制日志的次数
| Rpl_semi_sync_master_wait_sessions | 0 | 当前有几个线程在等备库响应
| Rpl_semi_sync_master_yes_tx | 7 | Semi-sync模式下，成功的事务数
+--------------------------------------------+-------+
15 rows in set (0.00 sec)
root@localhost [zw3306]>show global variables like '%semi%';
+-------------------------------------------+------------+
| Variable_name | Value |
+-------------------------------------------+------------+
| rpl_semi_sync_master_enabled | ON |
| rpl_semi_sync_master_timeout | 1000 |
| rpl_semi_sync_master_trace_level | 32 |
| rpl_semi_sync_master_wait_for_slave_count | 1 |
| rpl_semi_sync_master_wait_no_slave | ON |
| rpl_semi_sync_master_wait_point | AFTER_SYNC |
| rpl_semi_sync_slave_enabled | ON |
| rpl_semi_sync_slave_trace_level | 32 |
+-------------------------------------------+------------+
8 rows in set (0.00 sec)
Rpl_semi_sync_master_no_tx 如果这个值很大就有问题
也有其他的原因；
mysql> 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 | 17 |
| Rpl_semi_sync_master_no_times | 1 |
| Rpl_semi_sync_master_no_tx | 10 | 不是用半同步复制的
| Rpl_semi_sync_master_status | OFF |
| Rpl_semi_sync_master_timefunc_failures | 0 |
| Rpl_semi_sync_master_tx_avg_wait_time | 410 |
| Rpl_semi_sync_master_tx_wait_time | 2876 |
| Rpl_semi_sync_master_tx_waits | 7 |
| Rpl_semi_sync_master_wait_pos_backtraverse | 0 |
| Rpl_semi_sync_master_wait_sessions | 0 |
| Rpl_semi_sync_master_yes_tx | 7 |
+--------------------------------------------+-------+
14 rows in set (0.01 sec)
操作10个事物，可以发现都是 Rpl_semi_sync_master_no_tx
参数说明：
在规定时间内master收到2个半同步的slave的ack才commit
set global rpl_semi_sync_master_wait_for_slave_count=2;超时时间，超过1秒表示超时
set global Rpl_semi_sync_master_net_wait_time=1000
