MySQL中interactive_timeout和wait_timeout的分歧【上海时

 

开启另外一个mysql客户端,查看会话变量的值

ERROR 2013 (HY000): Lost connection to MySQL server during query

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

 

INTERACTIVE_TIMEOUT:  10
WAIT_TIMEOUT:  28800

但通过jdbc测试,wait_timeout的值依旧是28800

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)

下面来测试一下,确认如下问题

2. 

Q2:会话变量wait_timeout的继承问题

开启另外一个mysql客户端,查看会话变量的值

只修改interactive_timeout参数

只修改全局变量interactive_timeout的值

首先,看看官方文档对于这两个参数的定义

 

发现,WAIT_TIMEOUT的值已经变为10了。

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));
         }
    }
}

同时,新增了一段程序,等待20s后,再次执行查询,报如下错误:

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。

interactive_timeout

 

可以看到,等待10s后再执行操作,连接已经断开。

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。

1. 控制连接最大空闲时长的wait_timeout参数。

 

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.

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。

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));
         }

    }
}

Q1:控制连接最大空闲时长的是哪个参数

结果输出如下:

查看jdbc的结果

     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。 

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)

 

总结

3. 

 

 

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)

验证

 

 

 

默认是28800,单位秒,即8个小时

  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

  1. 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)

验证:

WAIT_TIMEOUT的值依旧是28800.

INTERACTIVE_TIMEOUT:  28800
WAIT_TIMEOUT:  20

根据上述定义,两者的区别显而易见

MySQL中interactive_timeout和wait_timeout的分歧【上海时时乐走势图官网】。查看jdbc的结果

    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。

A1:wait_timeout

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。

默认同样是28800s

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_MySQL中interactive_timeout和wait_timeout的分歧【上海时时乐走势图官网】。connect()函数中使用了CLIENT_INTERACTIVE选项。

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:

 

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
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.
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)

1. 

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。

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

 

 只修改全局变量wait_timeout的值

MySQL中interactive_timeout和wait_timeout的分歧【上海时时乐走势图官网】。 

 

只修改wait_timeout参数

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)

wait_timeout

 

参考

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