MYSQL 半同步复制环境搭建
2017-12-13 16:02
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-----以下半同步复制是基于前面做的master-slave复制实现的，也就是异步复制。----------------------
1、master节点，加载semisynchronous插件
mysql> install plugin rpl_semi_sync_master SONAME 'semisync_master.so';
Query OK, 0 rows affected (0.01 sec)
查看库上插件信息，可以看到最后一行，已经有了该插件。
mysql> show plugins;
+----------------------------+----------+--------------------+----------------------+---------+
| Name | Status | Type | Library | License |
+----------------------------+----------+--------------------+----------------------+---------+
| binlog | ACTIVE | STORAGE ENGINE | NULL | GPL |
| mysql_native_password | ACTIVE | AUTHENTICATION | NULL | GPL |
| sha256_password | ACTIVE | AUTHENTICATION | NULL | GPL |
| CSV | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MEMORY | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MRG_MYISAM | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MyISAM | ACTIVE | STORAGE ENGINE | NULL | GPL |
| PERFORMANCE_SCHEMA | ACTIVE | STORAGE ENGINE | NULL | GPL |
| InnoDB | ACTIVE | STORAGE ENGINE | NULL | GPL |
| INNODB_TRX | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_LOCKS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_LOCK_WAITS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMP | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMP_RESET | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMPMEM | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMPMEM_RESET | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMP_PER_INDEX | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMP_PER_INDEX_RESET | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_BUFFER_PAGE | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_BUFFER_PAGE_LRU | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_BUFFER_POOL_STATS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_TEMP_TABLE_INFO | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_METRICS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_DEFAULT_STOPWORD | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_DELETED | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_BEING_DELETED | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_CONFIG | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_INDEX_CACHE | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_INDEX_TABLE | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_TABLES | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_TABLESTATS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_INDEXES | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_COLUMNS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_FIELDS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_FOREIGN | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_FOREIGN_COLS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_TABLESPACES | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_DATAFILES | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_VIRTUAL | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| partition | ACTIVE | STORAGE ENGINE | NULL | GPL |
| FEDERATED | DISABLED | STORAGE ENGINE | NULL | GPL |
| ARCHIVE | ACTIVE | STORAGE ENGINE | NULL | GPL |
| BLACKHOLE | ACTIVE | STORAGE ENGINE | NULL | GPL |
| ngram | ACTIVE | FTPARSER | NULL | GPL |
| validate_password | ACTIVE | VALIDATE PASSWORD | validate_password.so | GPL |
| rpl_semi_sync_master | ACTIVE | REPLICATION | semisync_master.so | GPL |
+----------------------------+----------+--------------------+----------------------+---------+
46 rows in set (0.00 sec)
--------------------------------------------------------------------------------------------------
2、slave节点，也需加载插件
mysql> install plugin rpl_semi_sync_slave SONAME 'semisync_slave.so';
Query OK, 0 rows affected (0.01 sec)
查看库上插件情况：看到最后一行，表明已经加载
mysql> show plugins;
+----------------------------+----------+--------------------+----------------------+---------+
| Name | Status | Type | Library | License |
+----------------------------+----------+--------------------+----------------------+---------+
| binlog | ACTIVE | STORAGE ENGINE | NULL | GPL |
| mysql_native_password | ACTIVE | AUTHENTICATION | NULL | GPL |
| sha256_password | ACTIVE | AUTHENTICATION | NULL | GPL |
| CSV | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MEMORY | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MRG_MYISAM | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MyISAM | ACTIVE | STORAGE ENGINE | NULL | GPL |
| PERFORMANCE_SCHEMA | ACTIVE | STORAGE ENGINE | NULL | GPL |
| InnoDB | ACTIVE | STORAGE ENGINE | NULL | GPL |
| INNODB_TRX | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_LOCKS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_LOCK_WAITS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| I
4000
NNODB_CMP | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMP_RESET | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMPMEM | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMPMEM_RESET | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMP_PER_INDEX | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMP_PER_INDEX_RESET | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_BUFFER_PAGE | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_BUFFER_PAGE_LRU | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_BUFFER_POOL_STATS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_TEMP_TABLE_INFO | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_METRICS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_DEFAULT_STOPWORD | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_DELETED | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_BEING_DELETED | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_CONFIG | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_INDEX_CACHE | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_INDEX_TABLE | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_TABLES | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_TABLESTATS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_INDEXES | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_COLUMNS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_FIELDS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_FOREIGN | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_FOREIGN_COLS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_TABLESPACES | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_DATAFILES | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_VIRTUAL | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| partition | ACTIVE | STORAGE ENGINE | NULL | GPL |
| FEDERATED | DISABLED | STORAGE ENGINE | NULL | GPL |
| ARCHIVE | ACTIVE | STORAGE ENGINE | NULL | GPL |
| BLACKHOLE | ACTIVE | STORAGE ENGINE | NULL | GPL |
| ngram | ACTIVE | FTPARSER | NULL | GPL |
| validate_password | ACTIVE | VALIDATE PASSWORD | validate_password.so | GPL |
| rpl_semi_sync_slave | ACTIVE | REPLICATION | semisync_slave.so | GPL |
+----------------------------+----------+--------------------+----------------------+---------+
46 rows in set (0.00 sec)
-----------------------------------------------------------------------------------------------
3、通过设置参数，启动半同步复制
首先是master节点：
set global rpl_semi_sync_master_enabled = 1;
set global rpl_semi_sync_master_timeout = 3000; 默认10s，改成3s
slave节点：
set global rpl_semi_sync_slave_enabled = 1;
-----------------------------------------------------------------------------------------------
4、重新启动slave节点的IO_THREAD线程，这一步是为了让slave节点重新连接master节点，
注册成为半同步slave身份，如果不重启io_thread，那么slave就一直保持异步复制模式
mysql> stop slave io_thread;
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> start slave io_thread;
Query OK, 0 rows affected (0.00 sec)
-----------------------------------------------------------------------------------------------
5、太随意了，这个半同步复制就搭建完了，下面就做些测试，看看效果。
mysql的半同步插件，会将一些与同步相关的统计信息写入到状态变量中，因此我们可以通过查看
这些变量值，帮助我们判断当前的数据同步模式，也可监控同步状态。
show status like '%Rpl_semi_sync%';
master节点：
mysql> 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_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 (0.01 sec)
slave节点：只有一个变量
mysql> show status like '%Rpl_semi_sync%';
+----------------------------+-------+
| Variable_name | Value |
+----------------------------+-------+
| Rpl_semi_sync_slave_status | ON |
+----------------------------+-------+
1 row in set (0.00 sec)
此时：在master节点插入数据
mysql> use test;
Database changed
mysql> insert into t values(23);
Query OK, 1 row affected (0.01 sec)
mysql> select * from t;
+------+
| id |
+------+
| 1 |
| 2 |
| 3 |
| 23 |
+------+
4 rows in set (0.00 sec)
在slave节点查看：
mysql> select * from t;
+------+
| id |
+------+
| 1 |
| 2 |
| 3 |
+------+
3 rows in set (0.00 sec)
哇哇，出事了，没有同步过来，肿么回事？
在mater节点查看变量信息：
mysql> 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 | 1 |
| 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 | 1238 |
| Rpl_semi_sync_master_tx_wait_time | 1238 |
| Rpl_semi_sync_master_tx_waits | 1 |
| Rpl_semi_sync_master_wait_pos_backtraverse | 0 |
| Rpl_semi_sync_master_wait_sessions | 0 |
| Rpl_semi_sync_master_yes_tx | 1 |
+--------------------------------------------+-------+
14 rows in set (0.00 sec)
发现Rpl_semi_sync_master_yes_tx 值为1，表明当前已经成功发送到slave节点1个事务，
可是，为啥我slave节点没有收到？
于是我只好重启slave：
mysql> stop slave;
Query OK, 0 rows affected (0.00 sec)
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)
mysql> show status like '%semi%';
+----------------------------+-------+
| Variable_name | Value |
+----------------------------+-------+
| Rpl_semi_sync_slave_status | ON |
+----------------------------+-------+
1 row in set (0.00 sec)
mysql> select * from t;
+------+
| id |
+------+
| 1 |
| 2 |
| 3 |
| 23 |
+------+
4 rows in set (0.00 sec)
结果，数据就出来了。。可能是由于我在配置半同步的时候，先将slave节点的应用停掉了导致的。
再做一次插入，看看：
master节点：
mysql> insert into t values(24);
Query OK, 1 row affected (0.00 sec)
mysql> select * from t;
+------+
| id |
+------+
| 1 |
| 2 |
| 3 |
| 23 |
| 24 |
+------+
5 rows in set (0.00 sec)
mysql> 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 | 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 | 949 |
| Rpl_semi_sync_master_tx_wait_time | 1899 |
| 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)
查看slave节点：
mysql> select * from t;
+------+
| id |
+------+
| 1 |
| 2 |
| 3 |
| 23 |
| 24 |
+------+
5 rows in set (0.00 sec)
数据如期而至。
-------------------------------------------------------------------------------------------------
6、前面还记得我们设置了一个超时参数：set global rpl_semi_sync_master_timeout = 3000;
做一个测试，将slave节点的应用停掉，然后在master节点再次执行insert操作，看看会发生啥？
slave节点：
mysql> stop slave;
Query OK, 0 rows affected (0.00 sec)
master节点：
mysql> insert into t values(25);
Query OK, 1 row affected (3.00 sec)
仔细看看，发现这个简单的insert花费3秒钟时间，其实就是由于slave节点的复制停掉了，产生了超时。
那么超时的后果呢？
mysql> show 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 | 2 |
| Rpl_semi_sync_master_no_times | 1 |
| Rpl_semi_sync_master_no_tx | 1 |
| Rpl_semi_sync_master_status | OFF |
| Rpl_semi_sync_master_timefunc_failures | 0 |
| Rpl_semi_sync_master_tx_avg_wait_time | 949 |
| Rpl_semi_sync_master_tx_wait_time | 1899 |
| 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 (0.01 sec)
可以看到，Rpl_semi_sync_master_status 被自动置为OFF了
将slave节点应用开启：
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)
在master节点再次执行操作：
mysql> insert into t values(26);
Query OK, 1 row affected (0.01 sec)
查看slave：
mysql> select * from t;
+------+
| id |
+------+
| 1 |
| 2 |
| 3 |
| 23 |
| 24 |
| 25 |
| 26 |
+------+
7 rows in set (0.00 sec)
发现数据都过来了，包括之前的25
再看master节点的status：
mysql> show 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 | 4 |
| Rpl_semi_sync_master_no_times | 1 |
| Rpl_semi_sync_master_no_tx | 1 |
| Rpl_semi_sync_master_status | ON |
| Rpl_semi_sync_master_timefunc_failures | 0 |
| Rpl_semi_sync_master_tx_avg_wait_time | 831 |
| Rpl_semi_sync_master_tx_wait_time | 2493 |
| 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)
瞧瞧，Rpl_semi_sync_master_status 又自动置为on了。
------------------------------------------------------------------------------------------
简单总结一下：
半同步的搭建也很简单，加载个插件，设置点参数即可，相当方便。
当slave节点的复制应用出现问题的时候，master节点会根据设置的超时参数自动断掉两节点间的复
d191
制，
当slave节点恢复正常后，master节点自动恢复复制。
1、master节点，加载semisynchronous插件
mysql> install plugin rpl_semi_sync_master SONAME 'semisync_master.so';
Query OK, 0 rows affected (0.01 sec)
查看库上插件信息，可以看到最后一行，已经有了该插件。
mysql> show plugins;
+----------------------------+----------+--------------------+----------------------+---------+
| Name | Status | Type | Library | License |
+----------------------------+----------+--------------------+----------------------+---------+
| binlog | ACTIVE | STORAGE ENGINE | NULL | GPL |
| mysql_native_password | ACTIVE | AUTHENTICATION | NULL | GPL |
| sha256_password | ACTIVE | AUTHENTICATION | NULL | GPL |
| CSV | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MEMORY | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MRG_MYISAM | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MyISAM | ACTIVE | STORAGE ENGINE | NULL | GPL |
| PERFORMANCE_SCHEMA | ACTIVE | STORAGE ENGINE | NULL | GPL |
| InnoDB | ACTIVE | STORAGE ENGINE | NULL | GPL |
| INNODB_TRX | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_LOCKS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_LOCK_WAITS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMP | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMP_RESET | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMPMEM | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMPMEM_RESET | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMP_PER_INDEX | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMP_PER_INDEX_RESET | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_BUFFER_PAGE | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_BUFFER_PAGE_LRU | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_BUFFER_POOL_STATS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_TEMP_TABLE_INFO | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_METRICS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_DEFAULT_STOPWORD | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_DELETED | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_BEING_DELETED | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_CONFIG | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_INDEX_CACHE | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_INDEX_TABLE | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_TABLES | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_TABLESTATS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_INDEXES | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_COLUMNS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_FIELDS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_FOREIGN | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_FOREIGN_COLS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_TABLESPACES | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_DATAFILES | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_VIRTUAL | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| partition | ACTIVE | STORAGE ENGINE | NULL | GPL |
| FEDERATED | DISABLED | STORAGE ENGINE | NULL | GPL |
| ARCHIVE | ACTIVE | STORAGE ENGINE | NULL | GPL |
| BLACKHOLE | ACTIVE | STORAGE ENGINE | NULL | GPL |
| ngram | ACTIVE | FTPARSER | NULL | GPL |
| validate_password | ACTIVE | VALIDATE PASSWORD | validate_password.so | GPL |
| rpl_semi_sync_master | ACTIVE | REPLICATION | semisync_master.so | GPL |
+----------------------------+----------+--------------------+----------------------+---------+
46 rows in set (0.00 sec)
--------------------------------------------------------------------------------------------------
2、slave节点，也需加载插件
mysql> install plugin rpl_semi_sync_slave SONAME 'semisync_slave.so';
Query OK, 0 rows affected (0.01 sec)
查看库上插件情况：看到最后一行，表明已经加载
mysql> show plugins;
+----------------------------+----------+--------------------+----------------------+---------+
| Name | Status | Type | Library | License |
+----------------------------+----------+--------------------+----------------------+---------+
| binlog | ACTIVE | STORAGE ENGINE | NULL | GPL |
| mysql_native_password | ACTIVE | AUTHENTICATION | NULL | GPL |
| sha256_password | ACTIVE | AUTHENTICATION | NULL | GPL |
| CSV | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MEMORY | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MRG_MYISAM | ACTIVE | STORAGE ENGINE | NULL | GPL |
| MyISAM | ACTIVE | STORAGE ENGINE | NULL | GPL |
| PERFORMANCE_SCHEMA | ACTIVE | STORAGE ENGINE | NULL | GPL |
| InnoDB | ACTIVE | STORAGE ENGINE | NULL | GPL |
| INNODB_TRX | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_LOCKS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_LOCK_WAITS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| I
4000
NNODB_CMP | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMP_RESET | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMPMEM | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMPMEM_RESET | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMP_PER_INDEX | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_CMP_PER_INDEX_RESET | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_BUFFER_PAGE | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_BUFFER_PAGE_LRU | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_BUFFER_POOL_STATS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_TEMP_TABLE_INFO | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_METRICS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_DEFAULT_STOPWORD | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_DELETED | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_BEING_DELETED | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_CONFIG | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_INDEX_CACHE | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_FT_INDEX_TABLE | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_TABLES | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_TABLESTATS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_INDEXES | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_COLUMNS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_FIELDS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_FOREIGN | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_FOREIGN_COLS | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_TABLESPACES | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_DATAFILES | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| INNODB_SYS_VIRTUAL | ACTIVE | INFORMATION SCHEMA | NULL | GPL |
| partition | ACTIVE | STORAGE ENGINE | NULL | GPL |
| FEDERATED | DISABLED | STORAGE ENGINE | NULL | GPL |
| ARCHIVE | ACTIVE | STORAGE ENGINE | NULL | GPL |
| BLACKHOLE | ACTIVE | STORAGE ENGINE | NULL | GPL |
| ngram | ACTIVE | FTPARSER | NULL | GPL |
| validate_password | ACTIVE | VALIDATE PASSWORD | validate_password.so | GPL |
| rpl_semi_sync_slave | ACTIVE | REPLICATION | semisync_slave.so | GPL |
+----------------------------+----------+--------------------+----------------------+---------+
46 rows in set (0.00 sec)
-----------------------------------------------------------------------------------------------
3、通过设置参数，启动半同步复制
首先是master节点：
set global rpl_semi_sync_master_enabled = 1;
set global rpl_semi_sync_master_timeout = 3000; 默认10s，改成3s
slave节点：
set global rpl_semi_sync_slave_enabled = 1;
-----------------------------------------------------------------------------------------------
4、重新启动slave节点的IO_THREAD线程，这一步是为了让slave节点重新连接master节点，
注册成为半同步slave身份，如果不重启io_thread，那么slave就一直保持异步复制模式
mysql> stop slave io_thread;
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> start slave io_thread;
Query OK, 0 rows affected (0.00 sec)
-----------------------------------------------------------------------------------------------
5、太随意了，这个半同步复制就搭建完了，下面就做些测试，看看效果。
mysql的半同步插件，会将一些与同步相关的统计信息写入到状态变量中，因此我们可以通过查看
这些变量值，帮助我们判断当前的数据同步模式，也可监控同步状态。
show status like '%Rpl_semi_sync%';
master节点：
mysql> 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_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 (0.01 sec)
slave节点：只有一个变量
mysql> show status like '%Rpl_semi_sync%';
+----------------------------+-------+
| Variable_name | Value |
+----------------------------+-------+
| Rpl_semi_sync_slave_status | ON |
+----------------------------+-------+
1 row in set (0.00 sec)
此时：在master节点插入数据
mysql> use test;
Database changed
mysql> insert into t values(23);
Query OK, 1 row affected (0.01 sec)
mysql> select * from t;
+------+
| id |
+------+
| 1 |
| 2 |
| 3 |
| 23 |
+------+
4 rows in set (0.00 sec)
在slave节点查看：
mysql> select * from t;
+------+
| id |
+------+
| 1 |
| 2 |
| 3 |
+------+
3 rows in set (0.00 sec)
哇哇，出事了，没有同步过来，肿么回事？
在mater节点查看变量信息：
mysql> 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 | 1 |
| 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 | 1238 |
| Rpl_semi_sync_master_tx_wait_time | 1238 |
| Rpl_semi_sync_master_tx_waits | 1 |
| Rpl_semi_sync_master_wait_pos_backtraverse | 0 |
| Rpl_semi_sync_master_wait_sessions | 0 |
| Rpl_semi_sync_master_yes_tx | 1 |
+--------------------------------------------+-------+
14 rows in set (0.00 sec)
发现Rpl_semi_sync_master_yes_tx 值为1，表明当前已经成功发送到slave节点1个事务，
可是，为啥我slave节点没有收到？
于是我只好重启slave：
mysql> stop slave;
Query OK, 0 rows affected (0.00 sec)
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)
mysql> show status like '%semi%';
+----------------------------+-------+
| Variable_name | Value |
+----------------------------+-------+
| Rpl_semi_sync_slave_status | ON |
+----------------------------+-------+
1 row in set (0.00 sec)
mysql> select * from t;
+------+
| id |
+------+
| 1 |
| 2 |
| 3 |
| 23 |
+------+
4 rows in set (0.00 sec)
结果，数据就出来了。。可能是由于我在配置半同步的时候，先将slave节点的应用停掉了导致的。
再做一次插入，看看：
master节点：
mysql> insert into t values(24);
Query OK, 1 row affected (0.00 sec)
mysql> select * from t;
+------+
| id |
+------+
| 1 |
| 2 |
| 3 |
| 23 |
| 24 |
+------+
5 rows in set (0.00 sec)
mysql> 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 | 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 | 949 |
| Rpl_semi_sync_master_tx_wait_time | 1899 |
| 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)
查看slave节点：
mysql> select * from t;
+------+
| id |
+------+
| 1 |
| 2 |
| 3 |
| 23 |
| 24 |
+------+
5 rows in set (0.00 sec)
数据如期而至。
-------------------------------------------------------------------------------------------------
6、前面还记得我们设置了一个超时参数：set global rpl_semi_sync_master_timeout = 3000;
做一个测试，将slave节点的应用停掉，然后在master节点再次执行insert操作，看看会发生啥？
slave节点：
mysql> stop slave;
Query OK, 0 rows affected (0.00 sec)
master节点：
mysql> insert into t values(25);
Query OK, 1 row affected (3.00 sec)
仔细看看，发现这个简单的insert花费3秒钟时间，其实就是由于slave节点的复制停掉了，产生了超时。
那么超时的后果呢？
mysql> show 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 | 2 |
| Rpl_semi_sync_master_no_times | 1 |
| Rpl_semi_sync_master_no_tx | 1 |
| Rpl_semi_sync_master_status | OFF |
| Rpl_semi_sync_master_timefunc_failures | 0 |
| Rpl_semi_sync_master_tx_avg_wait_time | 949 |
| Rpl_semi_sync_master_tx_wait_time | 1899 |
| 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 (0.01 sec)
可以看到，Rpl_semi_sync_master_status 被自动置为OFF了
将slave节点应用开启：
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)
在master节点再次执行操作：
mysql> insert into t values(26);
Query OK, 1 row affected (0.01 sec)
查看slave：
mysql> select * from t;
+------+
| id |
+------+
| 1 |
| 2 |
| 3 |
| 23 |
| 24 |
| 25 |
| 26 |
+------+
7 rows in set (0.00 sec)
发现数据都过来了，包括之前的25
再看master节点的status：
mysql> show 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 | 4 |
| Rpl_semi_sync_master_no_times | 1 |
| Rpl_semi_sync_master_no_tx | 1 |
| Rpl_semi_sync_master_status | ON |
| Rpl_semi_sync_master_timefunc_failures | 0 |
| Rpl_semi_sync_master_tx_avg_wait_time | 831 |
| Rpl_semi_sync_master_tx_wait_time | 2493 |
| 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)
瞧瞧，Rpl_semi_sync_master_status 又自动置为on了。
------------------------------------------------------------------------------------------
简单总结一下：
半同步的搭建也很简单，加载个插件，设置点参数即可，相当方便。
当slave节点的复制应用出现问题的时候，master节点会根据设置的超时参数自动断掉两节点间的复
d191
制，
当slave节点恢复正常后，master节点自动恢复复制。
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