MySQL中interactive_timeout和wait_timeout的區(qū)別
在用mysql客戶端對數(shù)據(jù)庫進(jìn)行操作時(shí),打開終端窗口,如果一段時(shí)間沒有操作,再次操作時(shí),常常會報(bào)如下錯(cuò)誤:
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(gè)報(bào)錯(cuò)信息就意味著當(dāng)前的連接已經(jīng)斷開,需要重新建立連接。
那么,連接的時(shí)長是如何確認(rèn)的?
其實(shí),這個(gè)與interactive_timeout和wait_timeout的設(shè)置有關(guān)。
首先,看看官方文檔對于這兩個(gè)參數(shù)的定義
interactive_timeout
默認(rèn)是28800,單位秒,即8個(gè)小時(shí)
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(rèn)同樣是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(jù)上述定義,兩者的區(qū)別顯而易見
1> interactive_timeout針對交互式連接,wait_timeout針對非交互式連接。所謂的交互式連接,即在mysql_real_connect()函數(shù)中使用了CLIENT_INTERACTIVE選項(xiàng)。
說得直白一點(diǎn),通過mysql客戶端連接數(shù)據(jù)庫是交互式連接,通過jdbc連接數(shù)據(jù)庫是非交互式連接。
2> 在連接啟動的時(shí)候,根據(jù)連接的類型,來確認(rèn)會話變量wait_timeout的值是繼承于全局變量wait_timeout,還是interactive_timeout。
下面來測試一下,確認(rèn)如下問題
1. 控制連接最大空閑時(shí)長的是哪個(gè)參數(shù)。
2. 會話變量wait_timeout的繼承問題
Q1:控制連接最大空閑時(shí)長的是哪個(gè)參數(shù)
A1:wait_timeout
驗(yàn)證
只修改wait_timeout參數(shù)
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后再執(zhí)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后再執(zhí)行操作,連接已經(jīng)斷開。
只修改interactive_timeout參數(shù)
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后執(zhí)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:如果是交互式連接,則繼承全局變量interactive_timeout的值,如果是非交互式連接,則繼承全局變量wait_timeout的值。
驗(yàn)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)
開啟另外一個(gè)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(fā)現(xiàn),WAIT_TIMEOUT的值已經(jīng)變?yōu)?0了。
但通過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(jié)果輸出如下:
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)
開啟另外一個(gè)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(jié)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(jié)果
INTERACTIVE_TIMEOUT: 28800 WAIT_TIMEOUT: 20
同時(shí),新增了一段程序,等待20s后,再次執(zhí)行查詢,報(bào)如下錯(cuò)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(jié)
1. 控制連接最大空閑時(shí)長的wait_timeout參數(shù)。
2. 對于非交互式連接,類似于jdbc連接,wait_timeout的值繼承自服務(wù)器端全局變量wait_timeout。
對于交互式連接,類似于mysql客戶單連接,wait_timeout的值繼承自服務(wù)器端全局變量interactive_timeout。
3. 判斷一個(gè)連接的空閑時(shí)間,可通過show processlist輸出中Sleep狀態(tài)的時(shí)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)
以上所述是小編給大家介紹的MySQL中interactive_timeout和wait_timeout的區(qū)別,希望對大家有所幫助,如果大家有任何疑問請給我留言,小編會及時(shí)回復(fù)大家的。在此也非常感謝大家對腳本之家網(wǎng)站的支持!
相關(guān)文章
讓MySQL數(shù)據(jù)庫跑的更快 為數(shù)據(jù)減肥
在MySQL數(shù)據(jù)庫優(yōu)化工作中,使數(shù)據(jù)盡可能的小,使表在硬盤上占據(jù)的空間盡可能的小,這是最常用、也是最有效的手段之一。2011-03-03MySQL事務(wù)的ACID特性以及并發(fā)問題方案
這篇文章主要介紹了MySQL事務(wù)的ACID特性以及并發(fā)問題方案,文章圍繞主題展開詳細(xì)的內(nèi)容介紹,具有一定的參考價(jià)值,需要的小伙伴可以參考一下2022-07-07

Mysql中日期和時(shí)間函數(shù)應(yīng)用不用求人