MySQL5.7 interactive_timeout 和 wait_timeout 解析
实验基础：
MySQL 版本：5.7.28
交互连接方式进行测试
一、起始状况
开始实验前，interactive_timeout和wait_timeout的global和session级都是28800s
开启两个session，以下简称session1、session2
mysql> select @@global.interactive_timeout,@@session.interactive_timeout;
+------------------------------+-------------------------------+
| @@global.interactive_timeout | @@session.interactive_timeout |
+------------------------------+-------------------------------+
| 28800 | 28800 |
+------------------------------+-------------------------------+
1 row in set (0.00 sec)
mysql> select @@global.wait_timeout,@@session.wait_timeout;
+-----------------------+------------------------+
| @@global.wait_timeout | @@session.wait_timeout |
+-----------------------+------------------------+
| 28800 | 28800 |
+-----------------------+------------------------+
1 row in set (0.00 sec)
二、设置global级的interactive_timeout
1、session1
mysql> set global interactive_timeout = 600;
Query OK, 0 rows affected (0.00 sec)
mysql> select @@global.interactive_timeout,@@session.interactive_timeout;
+------------------------------+-------------------------------+
| @@global.interactive_timeout | @@session.interactive_timeout |
+------------------------------+-------------------------------+
| 600 | 28800 |
+------------------------------+-------------------------------+
1 row in set (0.00 sec)
mysql> select @@global.wait_timeout,@@session.wait_timeout;
+-----------------------+------------------------+
| @@global.wait_timeout | @@session.wait_timeout |
+-----------------------+------------------------+
| 28800 | 28800 |
+-----------------------+------------------------+
1 row in set (0.00 sec)
设置global级的interactive_timeout会影响当前session的@@global.interactive_timeout
2、session2
mysql> select @@global.interactive_timeout,@@session.interactive_timeout;
+------------------------------+-------------------------------+
| @@global.interactive_timeout | @@session.interactive_timeout |
+------------------------------+-------------------------------+
| 600 | 28800 |
+------------------------------+-------------------------------+
1 row in set (0.00 sec)
mysql> select @@global.wait_timeout,@@session.wait_timeout;
+-----------------------+------------------------+
| @@global.wait_timeout | @@session.wait_timeout |
+-----------------------+------------------------+
| 28800 | 28800 |
+-----------------------+------------------------+
1 row in set (0.00 sec)
设置global级的interactive_timeout会影响其他未退出登录session的@@global.interactive_timeout
3、新session
mysql> select @@global.interactive_timeout,@@session.interactive_timeout;
+------------------------------+-------------------------------+
| @@global.interactive_timeout | @@session.interactive_timeout |
+------------------------------+-------------------------------+
| 600 | 600 |
+------------------------------+-------------------------------+
1 row in set (0.00 sec)
mysql> select @@global.wait_timeout,@@session.wait_timeout;
+-----------------------+------------------------+
| @@global.wait_timeout | @@session.wait_timeout |
+-----------------------+------------------------+
| 28800 | 600 |
+-----------------------+------------------------+
1 row in set (0.00 sec)
设置global级的interactive_timeout会影响其他新登录session的@@global.interactive_timeout、@@session.interactive_timeout、@@session.wait_timeout
三、设置session 级别的interactive_timeout
1、session1
mysql> set session interactive_timeout = 300;
Query OK, 0 rows affected (0.00 sec)
mysql> select @@global.interactive_timeout,@@session.interactive_timeout;
+------------------------------+-------------------------------+
| @@global.interactive_timeout | @@session.interactive_timeout |
+------------------------------+-------------------------------+
| 600 | 300 |
+------------------------------+-------------------------------+
1 row in set (0.00 sec)
mysql> select @@global.wait_timeout,@@session.wait_timeout;
+-----------------------+------------------------+
| @@global.wait_timeout | @@session.wait_timeout |
+-----------------------+------------------------+
| 28800 | 600 |
+-----------------------+------------------------+
1 row in set (0.00 sec)
设置session级的interactive_timeout会影响当前session的@@session.interactive_timeout
2、session2
mysql> select @@global.interactive_timeout,@@session.interactive_timeout;
+------------------------------+-------------------------------+
| @@global.interactive_timeout | @@session.interactive_timeout |
+------------------------------+-------------------------------+
| 600 | 600 |
+------------------------------+-------------------------------+
1 row in set (0.00 sec)
mysql> select @@global.wait_timeout,@@session.wait_timeout;
+-----------------------+------------------------+
| @@global.wait_timeout | @@session.wait_timeout |
+-----------------------+------------------------+
| 28800 | 600 |
+-----------------------+------------------------+
1 row in set (0.00 sec)
设置session级的interactive_timeout不会影响其他未退出登录session的interactive_timeout
3、新session
mysql> select @@global.interactive_timeout,@@session.interactive_timeout;
+------------------------------+-------------------------------+
| @@global.interactive_timeout | @@session.interactive_timeout |
+------------------------------+-------------------------------+
| 600 | 600 |
+------------------------------+-------------------------------+
1 row in set (0.00 sec)
mysql> select @@global.wait_timeout,@@session.wait_timeout;
+-----------------------+------------------------+
| @@global.wait_timeout | @@session.wait_timeout |
+-----------------------+------------------------+
| 28800 | 600 |
+-----------------------+------------------------+
1 row in set (0.00 sec)
设置session级的interactive_timeout不会影响其他新登录session的interactive_timeout
四、设置global 级别的wait_timeout
1、session1
mysql> set global wait_timeout= 200;
Query OK, 0 rows affected (0.00 sec)
mysql> select @@global.interactive_timeout,@@session.interactive_timeout;
+------------------------------+-------------------------------+
| @@global.interactive_timeout | @@session.interactive_timeout |
+------------------------------+-------------------------------+
| 600 | 600 |
+------------------------------+-------------------------------+
1 row in set (0.00 sec)
mysql> select @@global.wait_timeout,@@session.wait_timeout;
+-----------------------+------------------------+
| @@global.wait_timeout | @@session.wait_timeout |
+-----------------------+------------------------+
| 200 | 600 |
+-----------------------+------------------------+
1 row in set (0.00 sec)
设置global级的wait_timeout会影响当前session的@@global.wait_timeout
2、session2
mysql> select @@global.interactive_timeout,@@session.interactive_timeout;
+------------------------------+-------------------------------+
| @@global.interactive_timeout | @@session.interactive_timeout |
+------------------------------+-------------------------------+
| 600 | 600 |
+------------------------------+-------------------------------+
1 row in set (0.00 sec)
mysql> select @@global.wait_timeout,@@session.wait_timeout;
+-----------------------+------------------------+
| @@global.wait_timeout | @@session.wait_timeout |
+-----------------------+------------------------+
| 200 | 600 |
+-----------------------+------------------------+
1 row in set (0.00 sec)
设置global级的wait_timeout会影响其他未退出登录session的@@global.wait_timeout
3、新session
mysql> select @@global.interactive_timeout,@@session.interactive_timeout;
+------------------------------+-------------------------------+
| @@global.interactive_timeout | @@session.interactive_timeout |
+------------------------------+-------------------------------+
| 600 | 600 |
+------------------------------+-------------------------------+
1 row in set (0.00 sec)
mysql> select @@global.wait_timeout,@@session.wait_timeout;
+-----------------------+------------------------+
| @@global.wait_timeout | @@session.wait_timeout |
+-----------------------+------------------------+
| 200 | 600 |
+-----------------------+------------------------+
1 row in set (0.00 sec)
设置global级的wait_timeout会影响其他新登录session的@@global.wait_timeout，但@@session.wait_timeout没有改变
五、设置session 级别的wait_timeout
1、session1
mysql> set session wait_timeout= 100;
Query OK, 0 rows affected (0.00 sec)
mysql> select @@global.interactive_timeout,@@session.interactive_timeout;
+------------------------------+-------------------------------+
| @@global.interactive_timeout | @@session.interactive_timeout |
+------------------------------+-------------------------------+
| 600 | 600 |
+------------------------------+-------------------------------+
1 row in set (0.00 sec)
mysql> select @@global.wait_timeout,@@session.wait_timeout;
+-----------------------+------------------------+
| @@global.wait_timeout | @@session.wait_timeout |
+-----------------------+------------------------+
| 200 | 100 |
+-----------------------+------------------------+
1 row in set (0.00 sec)
设置session级的wait_timeout会影响当前session的@@session.wait_timeout
2、session2
mysql> select @@global.interactive_timeout,@@session.interactive_timeout;
+------------------------------+-------------------------------+
| @@global.interactive_timeout | @@session.interactive_timeout |
+------------------------------+-------------------------------+
| 600 | 600 |
+------------------------------+-------------------------------+
1 row in set (0.00 sec)
mysql> select @@global.wait_timeout,@@session.wait_timeout;
+-----------------------+------------------------+
| @@global.wait_timeout | @@session.wait_timeout |
+-----------------------+------------------------+
| 200 | 600 |
+-----------------------+------------------------+
1 row in set (0.00 sec)
设置session级的wait_timeout不会影响其他未退出登录session的wait_timeout
3、新session
mysql> select @@global.interactive_timeout,@@session.interactive_timeout;
+------------------------------+-------------------------------+
| @@global.interactive_timeout | @@session.interactive_timeout |
+------------------------------+-------------------------------+
| 600 | 600 |
+------------------------------+-------------------------------+
1 row in set (0.00 sec)
mysql> select @@global.wait_timeout,@@session.wait_timeout;
+-----------------------+------------------------+
| @@global.wait_timeout | @@session.wait_timeout |
+-----------------------+------------------------+
| 200 | 600 |
+-----------------------+------------------------+
1 row in set (0.00 sec)
设置session级的wait_timeout不会影响其他新登录session的wait_timeout
六、总结
1、
设置session级的interactive_timeout仅会影响当前session的@@session.interactive_timeout，退出即失效
设置session级的wait_timeout仅会影响当前session的@@session.wait_timeout，退出即失效
这跟我们的固有理论相符。
2、
设置global 级别的wait_timeout会影响当前session的@@global.wait_timeout、其他未退出登录session的@@global.wait_timeout，以及新登录session的@@global.wait_timeout
设置global级的interactive_timeout会影响当前session的@@global.interactive_timeout、其他未退出登录session的@@global.interactive_timeout，以及新登录session的@@global.interactive_timeout
这跟我们的固有理论相符。
3、
@@session.interactive_timeout继承了@@global.interactive_timeout的值。（这跟我们的固有理论相符）
设置global级的wait_timeout不会影响新登录session的@@session.wait_timeout
设置global级的interactive_timeout会影响其他新登录session的@@session.wait_timeout
最后两点就与众不同了。
简言之，交互连接下的session级的wait_timeout，没有继承@@global.wait_timeout，反而继承了@@global.interactive_timeout的值。
这就意味着，如果需要修改全局wait_timeout的值，使之对新的交互连接生效，常规思路的set global wait_timeout将失效。应该通过set global interactive_timeout的方式去修改wait_timeout。
注：非交互模式下，session级的wait_timeout继承的是global级的wait_timeout
################
#非交互的实验待补充#
################
七、手册溯源
摘录一段官方文档对此的释疑：
wait_timeout: The number of seconds the server waits for activity on a noninteractive connection before closing it.
等待非交互连接转为activity状态的超时时间（即转入Sleep状态后开始计算超时时间）
On thread startup, the session wait_timeout value is initialized from the global wait_timeout value or from the global interactive_timeout value, depending on the type of client (as defined by the CLIENT_INTERACTIVE connect option to mysql_real_connect()). See also interactive_timeout.
新连接启动后，session级的wait_timeout值是根据：global级的wait_timeout值、或者global级的interactive_timeout值初始化而来，不同的客户端连接类型会选择不同的初始化参考值。
interactive_timeout: The number of seconds the server waits for activity on an interactive connection before closing it. An interactive client is defined as a client that uses the CLIENT_INTERACTIVE option to mysql_real_connect(). See also wait_timeout.
等待交互连接转为activity状态的超时时间
CLIENT_INTERACTIVE: Permit interactive_timeout seconds of inactivity (rather than wait_timeout seconds) before closing the connection. The client's session wait_timeout variable is set to the value of the session interactive_timeout variable.
mysql_real_connect() 的client_flag默认为0，可自定义flag，例如：CLIENT_INTERACTIVE
连接池中默认是怎么设置的呢？待研究。。。
参考文档：
【MySQL】浅析interactive_timeout和wait_timeout
MySQL中interactive_timeout和wait_timeout的区别
MySQL中 timeout相关参数解析
[MySQL分享]--interactive_timeout和wait_timeout小结（interactive_timeout会覆盖wait_timeout）