MySQL timeout相關引數解析和測試 • cenalulu's Tech Blog
阿新 • • 發佈：2018-12-23
MySQL中有兩個關於連線超時的配置項:
wait_timeout和interactive_timeout。他們之間在某些條件下會互相繼承，那究竟這兩個引數會在什麼情況下起作用呢？ 本文將會通過一些測試例項來證明總結兩者的相互關係。
引數介紹
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
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
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.
CLIENT_INTERACTIVE
Permit interactive_timeout seconds (instead of wait_timeout
wait_timeout variable is set to the value of the session interactive_timeout variable.
簡單的說 interactive就是互動式的終端，例如在shell裡面直接執行mysql，出現形如mysql>的提示符後就是互動式的連線。而mysql -e ‘select 1’ 這樣的直接返回結果的方式就是非互動式的連線。
測試及驗證
繼承關係
Q：通過socket連線 timeout會從哪個global timeout繼承 A：由下例可見，通過socket登入，timeout 繼承於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.sock
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 4
Server 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 its
affiliates. Other names may be trademarks of their respective
owners.
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：通過TCP/IP client 連線， timeout會從哪個global timeout繼承
A：由下例可見，通過TCP/IP client 連線後的wait_timeout 仍然繼承於 global.interactive_timeout
mysql -uroot -ppassword -h 127.0.0.1 --port 3310
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 6
Server 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 its
affiliates. Other names may be trademarks of their respective
owners.
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)起效關係
Q：timeout值，對於處於執行狀態SQL語句是否起效（即是否等價於執行超時）？ A：由下例可見SQL正在執行狀態的等待時間不計入timeout時間。即SQL執行再久也不會因為timeout的配置而中斷
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：同一個session中，wait_timeout 和 interacitve_timeout是否都會生效。
A：只有wait_timeout 會真正起到超時限制的作用
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)
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是否都會作為超時判斷依據？ A：只有session級別 timeout 會起作用。即一個session開始後，無論如何修改global級別的timeout都不會影響該session
- 測試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)- 測試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)總結
由以上的階段測試可以獲得以下結論。
- 超時時間只對非活動狀態的connection進行計算。
- 超時時間只以session級別的
wait_timeout為超時依據，global級別只決定session初始化時的超時預設值。 - 互動式連線的
wait_timeout繼承於global的interactive_timeout。非互動式連線的wait_timeout繼承於global的wait_timeout - 繼承關係和超時對 TCP/IP 和 Socket 連線均有效果