MySQL中 timeout相关参数解析_MySQL

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前言：

MySQL中有两个关于连接超时的配置项。他们之间在某些条件下会互相继承，那究竟这两个参数会在什么情况下起作用呢？

本文将会通过一些测试实例来证明总结两者的相互关系。

参数介绍：

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 alsowait_timeout.

wait_timeout

The number of seconds the server waits for activity on a noninteractive connection before closing it. Before MySQL 5.1.41, this timeout applies only to TCP/IP connections, not to connections made through Unix socket files, named pipes, or shared memory.

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_INTERACTIVEconnect option to mysql_real_connect()). See also interactive_timeout.

CLIENT_INTERACTIVE

Permit interactive_timeout seconds (instead of wait_timeout seconds) of inactivity before closing the connection. The client's sessionwait_timeout variable is set to the value of the session interactive_timeout variable.

简单的说 interactive就是交互式的终端，例如在shell里面直接执行mysql，出现 mysql> 后就是交互式的连接。而mysql -e 'select 1' 这样的直接返回结果的方式就是非交互式的连接。

第二部分 测试

2.1 继承关系

Q：通过Socket连接 timeout会从哪个global timeout继承

A：由下例可见，通过socket登录，timeout 继承于global.interactive_timeout;

mysql> set global interactive_timeout =  11111;Query OK, 0 rows affected (0.00 sec)mysql> set global wait_timeout = 22222;Query OK, 0 rows affected (0.00 sec)mysql> show global variables like '%timeout%';+----------------------------+----------+| Variable_name              | Value    |+----------------------------+----------+| connect_timeout            | 10       || delayed_insert_timeout     | 300      || innodb_lock_wait_timeout   | 50       || innodb_rollback_on_timeout | OFF      || interactive_timeout        | 11111    || lock_wait_timeout          | 31536000 || net_read_timeout           | 30       || net_write_timeout          | 60       || slave_net_timeout          | 3600     || wait_timeout               | 22222    |+----------------------------+----------+10 rows in set (0.00 sec)mysql -uroot -ppassword -S /usr/local/mysql3310/mysql.sockWelcome to the MySQL monitor.  Commands end with ; or /g.Your MySQL connection id is 4Server version: 5.5.16-log MySQL Community Server (GPL)Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '/h' for help. Type '/c' to clear the current input statement.mysql> show session variables like '%timeout%';+----------------------------+----------+| Variable_name              | Value    |+----------------------------+----------+| connect_timeout            | 10       || delayed_insert_timeout     | 300      || innodb_lock_wait_timeout   | 50       || innodb_rollback_on_timeout | OFF      || interactive_timeout        | 11111    || lock_wait_timeout          | 31536000 || net_read_timeout           | 30       || net_write_timeout          | 60       || slave_net_timeout          | 3600     || wait_timeout               | 11111    |+----------------------------+----------+10 rows in set (0.00 sec)

　　

Q：通过TCP/IP client 连接， timeout会从哪个global timeout继承

A：由下例可见，通过TCP/IP client 连接后的wait_timeout 仍然继承于 global.interactive_timeout

mysql -uroot -ppassword -h 127.0.0.1 --port 3310Welcome to the MySQL monitor.  Commands end with ; or /g.Your MySQL connection id is 6Server version: 5.5.16-log MySQL Community Server (GPL)Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '/h' for help. Type '/c' to clear the current input statement.mysql> show session variables like '%timeout%';+----------------------------+----------+| Variable_name              | Value    |+----------------------------+----------+| connect_timeout            | 10       || delayed_insert_timeout     | 300      || innodb_lock_wait_timeout   | 50       || innodb_rollback_on_timeout | OFF      || interactive_timeout        | 11111    || lock_wait_timeout          | 31536000 || net_read_timeout           | 30       || net_write_timeout          | 60       || slave_net_timeout          | 3600     || wait_timeout               | 11111    |+----------------------------+----------+10 rows in set (0.00 sec)

　　

2.2 起效关系

Q：timeout值，对于正在运行用的语句是否起效？

A：由下例可见SQL正在执行状态的等待时间不计入timeout时间

mysql> set session wait_timeout=10;Query OK, 0 rows affected (0.00 sec)mysql> set session interactive_timeout=10;Query OK, 0 rows affected (0.00 sec)mysql> select 1,sleep(20) from dual;+---+-----------+| 1 | sleep(20) |+---+-----------+| 1 |         0 |+---+-----------+1 row in set (20.00 sec)mysql> mysql> show session variables like '%timeout%';+----------------------------+----------+| Variable_name              | Value    |+----------------------------+----------+| connect_timeout            | 10       || delayed_insert_timeout     | 300      || innodb_lock_wait_timeout   | 50       || innodb_rollback_on_timeout | OFF      || interactive_timeout        | 10       || lock_wait_timeout          | 31536000 || net_read_timeout           | 30       || net_write_timeout          | 60       || slave_net_timeout          | 3600     || wait_timeout               | 10       |+----------------------------+----------+

　　

Q：wait_timeout 和 interacitve_timeout 如何相互作用。

A：只有session.wait_timeout 会起效

mysql> set session interactive_timeout=10;Query OK, 0 rows affected (0.00 sec)mysql> set session wait_timeout=20;Query OK, 0 rows affected (0.00 sec)---------------------another connection-------------------------mysql> show full processlist;+----+-------------+-----------------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+| Id | User        | Host            | db   | Command | Time   | State                                                                       | Info                  | Rows_sent | Rows_examined | Rows_read |+----+-------------+-----------------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+|  1 | system user |                 | NULL | Connect | 103749 | Slave has read all relay log; waiting for the slave I/O thread to update it | NULL                  |         0 |             0 |         1 ||  2 | system user |                 | NULL | Connect | 103750 | Connecting to master                                                        | NULL                  |         0 |             0 |         1 ||  3 | root        | localhost       | NULL | Query   |      0 | NULL                                                                        | show full processlist |         0 |             0 |        11 || 10 | root        | localhost:58946 | NULL | Sleep   |     20 |                                                                             | NULL                  |         0 |             0 |        11 |+----+-------------+-----------------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+4 rows in set (0.00 sec)mysql> show full processlist;+----+-------------+-----------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+| Id | User        | Host      | db   | Command | Time   | State                                                                       | Info                  | Rows_sent | Rows_examined | Rows_read |+----+-------------+-----------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+|  1 | system user |           | NULL | Connect | 103749 | Slave has read all relay log; waiting for the slave I/O thread to update it | NULL                  |         0 |             0 |         1 ||  2 | system user |           | NULL | Connect | 103750 | Connecting to master                                                        | NULL                  |         0 |             0 |         1 ||  3 | root        | localhost | NULL | Query   |      0 | NULL                                                                        | show full processlist |         0 |             0 |        11 |+----+-------------+-----------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+3 rows in set (0.00 sec)

　　

Q：global timeout和session timeout哪个起作用。

A：只有session timeout 会起作用。

测试1：

mysql> set session interactive_timeout = 10;

Query OK, 0 rows affected (0.00 sec)mysql> set session wait_timeout = 10;Query OK, 0 rows affected (0.00 sec)mysql> show session variables like '%timeout%';+----------------------------+----------+| Variable_name              | Value    |+----------------------------+----------+| interactive_timeout        | 10       || wait_timeout               | 10       |+----------------------------+----------+10 rows in set (0.00 sec)mysql> show global variables like '%timeout%';+----------------------------+----------+| Variable_name              | Value    |+----------------------------+----------+| interactive_timeout        | 20       || wait_timeout               | 20       |+----------------------------+----------+10 rows in set (0.00 sec)mysql> show full processlist;+----+-------------+-----------------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+| Id | User        | Host            | db   | Command | Time   | State                                                                       | Info                  | Rows_sent | Rows_examined | Rows_read |+----+-------------+-----------------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+|  3 | root        | localhost       | NULL | Query   |      0 | NULL                                                                        | show full processlist |         0 |             0 |        11 || 17 | root        | localhost:60585 | NULL | Sleep   |     10 |                                                                             | NULL                  |        10 |            10 |        11 |+----+-------------+-----------------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+2 rows in set (0.00 sec)mysql> show full processlist;+----+-------------+-----------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+| Id | User        | Host      | db   | Command | Time   | State                                                                       | Info                  | Rows_sent | Rows_examined | Rows_read |+----+-------------+-----------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+|  3 | root        | localhost | NULL | Query   |      0 | NULL                                                                        | show full processlist |         0 |             0 |        11 |+----+-------------+-----------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+1 rows in set (0.00 sec)

测试2：

mysql> show session variables like '%timeout%';+----------------------------+----------+| Variable_name              | Value    |+----------------------------+----------+| interactive_timeout        | 20       || wait_timeout               | 20       |+----------------------------+----------+10 rows in set (0.00 sec)mysql> show global variables like '%timeout%';+----------------------------+----------+| Variable_name              | Value    |+----------------------------+----------+| interactive_timeout        | 10       |
| wait_timeout               | 10       |+----------------------------+----------+10 rows in set (0.00 sec)mysql> show full processlist;+----+-------------+-----------------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+| Id | User        | Host            | db   | Command | Time   | State                                                                       | Info                  | Rows_sent | Rows_examined | Rows_read |+----+-------------+-----------------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+|  3 | root        | localhost       | NULL | Query   |      0 | NULL                                                                        | show full processlist |         0 |             0 |        11 || 19 | root        | localhost:50276 | NULL | Sleep   |     19 |                                                                             | NULL                  |        10 |            10 |        11 |+----+-------------+-----------------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+2 rows in set (0.00 sec)mysql> show full processlist;+----+-------------+-----------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+| Id | User        | Host      | db   | Command | Time   | State                                                                       | Info                  | Rows_sent | Rows_examined | Rows_read |+----+-------------+-----------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+|  3 | root        | localhost | NULL | Query   |      0 | NULL                                                                        | show full processlist |         0 |             0 |        11 |+----+-------------+-----------+------+---------+--------+-----------------------------------------------------------------------------+-----------------------+-----------+---------------+-----------+1 rows in set (0.00 sec)

　　

第三部分 总结

由以上的阶段测试可以获得以下结论。

1. 超时时间只对非活动状态的connection进行计算。

2. 超时时间指通过 session wait_timeout 起效。

3. 交互式连接的wait_timeout 继承于 global.interactive_timeout

非交互式连接的wait_timeout 继承于 global.wait_timeout

4. 继承关系和超时对 TCP/IP 和 Socket 连接均有效果

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