MySQL中interactive_timeout和wait_timeout的區別

時間 2019-11-10

標籤 mysql interactive timeout wait 區別欄目 MySQL 简体版

原文原文鏈接

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：html

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。java

那麼，鏈接的時長是如何確認的？mysql

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

首先，看看官方文檔對於這兩個參數的定義數據庫

interactive_timeout服務器

默認是28800，單位秒，即8個小時session

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_timeoutsocket

默認一樣是28800s函數

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測試

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

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

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

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

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

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

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

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

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

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

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

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)