MySQL中interactive_timeout和wait_timeout的区别

2017-01-13 14:39:52  mysqlinteractivewaittimeout

在用mysql客户端对数据库进行操作时,打开终端窗口,如果一段时间没有操作,再次操作时,常常会报如下错误:

ERROR 2013 (HY000): Lost connection to MySQL server during query ERROR 2006 (HY000): MySQL server has gone away No connection. Trying to reconnect...

这个报错信息就意味着当前的连接已经断开,需要重新建立连接。

那么,连接的时长是如何确认的?

其实,这个与interactive_timeout和wait_timeout的设置有关。

首先,看看官方文档对于这两个参数的定义

interactive_timeout

默认是28800,单位秒,即8个小时

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.

wait_timeout

默认同样是28800s

The number of seconds the server waits for activity on a noninteractive connection before closing it.

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.

根据上述定义,两者的区别显而易见

1> interactive_timeout针对交互式连接,wait_timeout针对非交互式连接。所谓的交互式连接,即在mysql_real_connect()函数中使用了CLIENT_INTERACTIVE选项。

说得直白一点,通过mysql客户端连接数据库是交互式连接,通过jdbc连接数据库是非交互式连接。

2> 在连接启动的时候,根据连接的类型,来确认会话变量wait_timeout的值是继承于全局变量wait_timeout,还是interactive_timeout。

下面来测试一下,确认如下问题

1. 控制连接最大空闲时长的是哪个参数。

2. 会话变量wait_timeout的继承问题

Q1:控制连接最大空闲时长的是哪个参数

A1:wait_timeout

验证

只修改wait_timeout参数

mysql> select variable_name,variable_value from information_schema.session_variables where variable_name in ('interactive_timeout','wait_timeout'); +---------------------+----------------+ | variable_name | variable_value | +---------------------+----------------+ | INTERACTIVE_TIMEOUT | 28800 | | WAIT_TIMEOUT | 28800 | +---------------------+----------------+ 2 rows in set (0.03 sec) mysql> set session WAIT_TIMEOUT=10; Query OK, 0 rows affected (0.00 sec) -------等待10s后再执行 mysql> select variable_name,variable_value from information_schema.session_variables where variable_name in ('interactive_timeout','wait_timeout'); ERROR 2013 (HY000): Lost connection to MySQL server during query

可以看到,等待10s后再执行操作,连接已经断开。

只修改interactive_timeout参数

mysql> select variable_name,variable_value from information_schema.session_variables where variable_name in ('interactive_timeout','wait_timeout'); +---------------------+----------------+ | variable_name | variable_value | +---------------------+----------------+ | INTERACTIVE_TIMEOUT | 28800 | | WAIT_TIMEOUT | 28800 | +---------------------+----------------+ 2 rows in set (0.06 sec) mysql> set session INTERACTIVE_TIMEOUT=10; Query OK, 0 rows affected (0.00 sec) ----------等待10s后执行 mysql> select variable_name,variable_value from information_schema.session_variables where variable_name in ('interactive_timeout','wait_timeout'); +---------------------+----------------+ | variable_name | variable_value | +---------------------+----------------+ | INTERACTIVE_TIMEOUT | 10 | | WAIT_TIMEOUT | 28800 | +---------------------+----------------+ 2 rows in set (0.06 sec)

Q2:会话变量wait_timeout的继承问题

A2:如果是交互式连接,则继承全局变量interactive_timeout的值,如果是非交互式连接,则继承全局变量wait_timeout的值。

验证:

只修改全局变量interactive_timeout的值

mysql> select variable_name,variable_value from information_schema.global_variables where variable_name in ('interactive_timeout','wait_timeout'); +---------------------+----------------+ | variable_name | variable_value | +---------------------+----------------+ | INTERACTIVE_TIMEOUT | 28800 | | WAIT_TIMEOUT | 28800 | +---------------------+----------------+ 2 rows in set (0.13 sec) mysql> set global INTERACTIVE_TIMEOUT=10; Query OK, 0 rows affected (0.00 sec) mysql> select variable_name,variable_value from information_schema.global_variables where variable_name in ('interactive_timeout','wait_timeout'); +---------------------+----------------+ | variable_name | variable_value | +---------------------+----------------+ | INTERACTIVE_TIMEOUT | 10 | | WAIT_TIMEOUT | 28800 | +---------------------+----------------+ 2 rows in set (0.00 sec)

开启另外一个mysql客户端,查看会话变量的值

mysql> select variable_name,variable_value from information_schema.session_variables where variable_name in ('interactive_timeout','wait_timeout'); +---------------------+----------------+ | variable_name | variable_value | +---------------------+----------------+ | INTERACTIVE_TIMEOUT | 10 | | WAIT_TIMEOUT | 10 | +---------------------+----------------+ 2 rows in set (0.00 sec)

发现,WAIT_TIMEOUT的值已经变为10了。

但通过jdbc测试,wait_timeout的值依旧是28800

public class Jdbc_test { @SuppressWarnings("static-access") public static void main(String[] args) throws Exception { Connection conn = null; Statement stmt = null; ResultSet rs = null; String url = "jdbc:mysql://192.168.244.10:3306/test"; String user = "root"; String password = "123456"; Class.forName("com.mysql.jdbc.Driver"); conn = DriverManager.getConnection(url, user, password); stmt = conn.createStatement(); String sql = "select variable_name,variable_value from information_schema.session_variables where variable_name in ('interactive_timeout','wait_timeout')"; rs = stmt.executeQuery(sql); while (rs.next()) { System.out .println(rs.getString(1)+": "+rs.getString(2)); } } }

结果输出如下:

INTERACTIVE_TIMEOUT: 10
WAIT_TIMEOUT: 28800

只修改全局变量wait_timeout的值

mysql> select variable_name,variable_value from information_schema.global_variables where variable_name in ('interactive_timeout','wa it_timeout');+---------------------+----------------+ | variable_name | variable_value | +---------------------+----------------+ | INTERACTIVE_TIMEOUT | 28800 | | WAIT_TIMEOUT | 28800 | +---------------------+----------------+ 2 rows in set (0.17 sec) mysql> set global WAIT_TIMEOUT=20; Query OK, 0 rows affected (0.07 sec) mysql> select variable_name,variable_value from information_schema.global_variables where variable_name in ('interactive_timeout','wa it_timeout');+---------------------+----------------+ | variable_name | variable_value | +---------------------+----------------+ | INTERACTIVE_TIMEOUT | 28800 | | WAIT_TIMEOUT | 20 | +---------------------+----------------+ 2 rows in set (0.00 sec)

开启另外一个mysql客户端,查看会话变量的值

mysql> select variable_name,variable_value from information_schema.session_variables where variable_name in ('interactive_timeout','wait_timeout'); +---------------------+----------------+ | variable_name | variable_value | +---------------------+----------------+ | INTERACTIVE_TIMEOUT | 28800 | | WAIT_TIMEOUT | 28800 | +---------------------+----------------+ 2 rows in set (0.03 sec)

WAIT_TIMEOUT的值依旧是28800.

查看jdbc的结果

public class Jdbc_test { @SuppressWarnings("static-access") public static void main(String[] args) throws Exception { Connection conn = null; Statement stmt = null; ResultSet rs = null; String url = "jdbc:mysql://192.168.244.10:3306/test"; String user = "root"; String password = "123456"; Class.forName("com.mysql.jdbc.Driver"); conn = DriverManager.getConnection(url, user, password); stmt = conn.createStatement(); String sql = "select variable_name,variable_value from information_schema.session_variables where variable_name in ('interactive_timeout','wait_timeout')"; rs = stmt.executeQuery(sql); while (rs.next()) { System.out .println(rs.getString(1)+": "+rs.getString(2)); } Thread.currentThread().sleep(21000); sql = "select 1 from dual"; rs = stmt.executeQuery(sql); while (rs.next()) { System.out .println(rs.getInt(1)); } } }

查看jdbc的结果

INTERACTIVE_TIMEOUT: 28800 WAIT_TIMEOUT: 20

同时,新增了一段程序,等待20s后,再次执行查询,报如下错误:

Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4-communicationsException: Communications link failure

Last packet sent to the server was 12 ms ago. at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) at java-l ang.reflect.Constructor.newInstance(Unknown Source) at com.mysql.jdbc.Util.handleNewInstance(Util.java:406) at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074) at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3009) at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2895) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3438) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1951) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2101) at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2548) at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2477) at com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1422) at com.victor_01.Jdbc_test.main(Jdbc_test.java:29) Caused by: java.SocketException: Software caused connection abort: recv failed at java.SocketInputStream.socketRead0(Native Method) at java.SocketInputStream.socketRead(Unknown Source) at java.SocketInputStream.read(Unknown Source) at java.SocketInputStream.read(Unknown Source) at com.mysql.jdbc.util.ReadAheadInputStream.fill(ReadAheadInputStream.java:113) at com.mysql.jdbc.util.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(ReadAheadInputStream.java:160) at com.mysql.jdbc.util.ReadAheadInputStream.read(ReadAheadInputStream.java:188) at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2452) at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2906) ... 8 more

总结

1. 控制连接最大空闲时长的wait_timeout参数。

2. 对于非交互式连接,类似于jdbc连接,wait_timeout的值继承自服务器端全局变量wait_timeout。

对于交互式连接,类似于mysql客户单连接,wait_timeout的值继承自服务器端全局变量interactive_timeout。

3. 判断一个连接的空闲时间,可通过show processlist输出中Sleep状态的时间

mysql> show processlist; +----+------+----------------------+------+---------+------+-------+------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+------+----------------------+------+---------+------+-------+------------------+ | 2 | root | localhost | NULL | Query | 0 | init | show processlist | | 6 | repl | 192.168.244.20:44641 | NULL | Sleep | 1154 | | NULL | +----+------+----------------------+------+---------+------+-------+------------------+ 2 rows in set (0.03 sec)

以上所述是小编给大家介绍的MySQL中interactive_timeout和wait_timeout的区别,希望对大家有所帮助,如果大家有任何疑问请给我留言,小编会及时回复大家的。在此也非常感谢大家对网站的支持!

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