MySQL中interactive_timeout和wait_timeout的區別

在用mysql客戶端對數據庫進行操做時，打開終端窗口，若是一段時間沒有操做，再次操做時，經常會報以下錯誤：

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

這個報錯信息就意味着當前的鏈接已經斷開，須要從新創建鏈接。

那麼，鏈接的時長是如何確認的？

其實，這個與interactive_timeout和wait_timeout的設置有關。

首先，看看官方文檔對於這兩個參數的定義

interactive_timeout

默認是28800，單位秒，即8個小時

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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

默認一樣是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.

根據上述定義，二者的區別顯而易見

1> interactive_timeout針對交互式鏈接，wait_timeout針對非交互式鏈接。所謂的交互式鏈接，即在mysql_real_connect()函數中使用了CLIENT_INTERACTIVE選項。

說得直白一點，經過mysql客戶端鏈接數據庫是交互式鏈接，經過jdbc鏈接數據庫是非交互式鏈接。

2> 在鏈接啓動的時候，根據鏈接的類型，來確認會話變量wait_timeout的值是繼承於全局變量wait_timeout，仍是interactive_timeout。

下面來測試一下，確認以下問題

1. 控制鏈接最大空閒時長的是哪一個參數。

2. 會話變量wait_timeout的繼承問題

Q1：控制鏈接最大空閒時長的是哪一個參數

A1：wait_timeout

驗證

只修改wait_timeout參數

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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後再執行 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

能夠看到，等待10s後再執行操做，鏈接已經斷開。

只修改interactive_timeout參數

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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後執行 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：會話變量wait_timeout的繼承問題

A2：若是是交互式鏈接，則繼承全局變量interactive_timeout的值，若是是非交互式鏈接，則繼承全局變量wait_timeout的值。

驗證：

只修改全局變量interactive_timeout的值

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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)

開啓另一個mysql客戶端，查看會話變量的值

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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)

發現，WAIT_TIMEOUT的值已經變爲10了。

但經過jdbc測試，wait_timeout的值依舊是28800

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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)); } } }

結果輸出以下：

INTERACTIVE_TIMEOUT: 10
WAIT_TIMEOUT: 28800

只修改全局變量wait_timeout的值

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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)

開啓另一個mysql客戶端，查看會話變量的值

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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的值依舊是28800.

查看jdbc的結果

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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的結果

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1 2	INTERACTIVE_TIMEOUT: 28800 WAIT_TIMEOUT: 20

同時，新增了一段程序，等待20s後，再次執行查詢，報以下錯誤：

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

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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

總結

1. 控制鏈接最大空閒時長的wait_timeout參數。

2. 對於非交互式鏈接，相似於jdbc鏈接，wait_timeout的值繼承自服務器端全局變量wait_timeout。

對於交互式鏈接，相似於mysql客戶單鏈接，wait_timeout的值繼承自服務器端全局變量interactive_timeout。

3. 判斷一個鏈接的空閒時間，可經過show processlist輸出中Sleep狀態的時間

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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)

以上所述是小編給你們介紹的MySQL中interactive_timeout和wait_timeout的區別，但願對你們有所幫助，若是你們有任何疑問請給我留言，小編會及時回覆你們的。在此也很是感謝你們對腳本之家網站的支持！