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：
?
| 123 | ERROR 2013 (HY000): Lost connection to MySQL server during queryERROR 2006 (HY000): MySQL server has gone awayNo 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
?
| 1 | 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
?
| 12345678 | 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','wait_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','wait_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
?
| 12 | INTERACTIVE_TIMEOUT: 28800WAIT_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 failedat 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> 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脚本之家网站的支持！
点击查看更多内容
为 TA 点赞
评论
共同学习，写下你的评论
评论加载中...
作者其他优质文章
正在加载中
感谢您的支持，我会继续努力的～
扫码打赏，你说多少就多少
赞赏金额会直接到老师账户
支付方式
打开微信扫一扫，即可进行扫码打赏哦