MySQL中interactive_timeout和wait_timeout的区别

短命女 2022-05-25 11:42 124阅读 0赞

# [MySQL中interactive\_timeout和wait\_timeout的区别][MySQL_interactive_timeout_wait_timeout] #

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**

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**

WAIT\_TIMEOUT的值依旧是28800.

**查看jdbc的结果**

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.lang.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.net.SocketException: Software caused connection abort: recv failed
        at java.net.SocketInputStream.socketRead0(Native Method)
        at java.net.SocketInputStream.socketRead(Unknown Source)
        at java.net.SocketInputStream.read(Unknown Source)
        at java.net.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_interactive_timeout_wait_timeout]: http://www.cnblogs.com/ivictor/p/5979731.html