MySQL 8小时了

不念不忘少年蓝@ 2022-06-05 02:22 143阅读 0赞

出现的情况如下：  
\`org.apache.ibatis.exceptions.PersistenceException:

### Error querying database. Cause: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure ###

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

### The error may exist in tk/mybatis/simple/mapper/CountryMapper.xml ###

### The error may involve tk.mybatis.simple.mapper.CountryMapper.selectAll ###

### The error occurred while executing a query ###

### Cause: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure ###

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.  
at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)  
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:122)  
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:113)  
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:108)  
at tk.mybatis.simple.mapper.CountryMapperTest.testSelectAll(CountryMapperTest.java:35)  
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)  
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)  
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)  
at java.lang.reflect.Method.invoke(Method.java:606)  
at org.junit.runners.model.FrameworkMethod1.runReflectiveCall(FrameworkMethod.java:50)atorg.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)atorg.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)atorg.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)atorg.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)atorg.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)atorg.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)atorg.junit.runners.ParentRunner  1. r u n R e f l e c t i v e C a l l ( F r a m e w o r k M e t h o d . j a v a : 50 ) a t o r g . j u n i t . i n t e r n a l . r u n n e r s . m o d e l . R e f l e c t i v e C a l l a b l e . r u n ( R e f l e c t i v e C a l l a b l e . j a v a : 12 ) a t o r g . j u n i t . r u n n e r s . m o d e l . F r a m e w o r k M e t h o d . i n v o k e E x p l o s i v e l y ( F r a m e w o r k M e t h o d . j a v a : 47 ) a t o r g . j u n i t . i n t e r n a l . r u n n e r s . s t a t e m e n t s . I n v o k e M e t h o d . e v a l u a t e ( I n v o k e M e t h o d . j a v a : 17 ) a t o r g . j u n i t . r u n n e r s . P a r e n t R u n n e r . r u n L e a f ( P a r e n t R u n n e r . j a v a : 325 ) a t o r g . j u n i t . r u n n e r s . B l o c k J U n i t 4 C l a s s R u n n e r . r u n C h i l d ( B l o c k J U n i t 4 C l a s s R u n n e r . j a v a : 78 ) a t o r g . j u n i t . r u n n e r s . B l o c k J U n i t 4 C l a s s R u n n e r . r u n C h i l d ( B l o c k J U n i t 4 C l a s s R u n n e r . j a v a : 57 ) a t o r g . j u n i t . r u n n e r s . P a r e n t R u n n e r 3.run(ParentRunner.java:290)  
at org.junit.runners.ParentRunner1.schedule(ParentRunner.java:71)atorg.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)atorg.junit.runners.ParentRunner.access  1. s c h e d u l e ( P a r e n t R u n n e r . j a v a : 71 ) a t o r g . j u n i t . r u n n e r s . P a r e n t R u n n e r . r u n C h i l d r e n ( P a r e n t R u n n e r . j a v a : 288 ) a t o r g . j u n i t . r u n n e r s . P a r e n t R u n n e r . a c c e s s 000(ParentRunner.java:58)  
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)  
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)  
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)  
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)  
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)  
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)  
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)  
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)  
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)  
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.  
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)  
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)  
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)  
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)  
at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)  
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:981)  
at com.mysql.jdbc.MysqlIO.(MysqlIO.java:339)  
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2253)  
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2286)  
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2085)  
at com.mysql.jdbc.ConnectionImpl.(ConnectionImpl.java:795)  
at com.mysql.jdbc.JDBC4Connection.(JDBC4Connection.java:44)  
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)  
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)  
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)  
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)  
at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)  
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:400)  
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:327)  
at java.sql.DriverManager.getConnection(DriverManager.java:571)  
at java.sql.DriverManager.getConnection(DriverManager.java:187)  
at org.apache.ibatis.datasource.unpooled.UnpooledDataSource.doGetConnection(UnpooledDataSource.java:201)  
at org.apache.ibatis.datasource.unpooled.UnpooledDataSource.doGetConnection(UnpooledDataSource.java:196)  
at org.apache.ibatis.datasource.unpooled.UnpooledDataSource.getConnection(UnpooledDataSource.java:93)  
at org.apache.ibatis.transaction.jdbc.JdbcTransaction.openConnection(JdbcTransaction.java:140)  
at org.apache.ibatis.transaction.jdbc.JdbcTransaction.getConnection(JdbcTransaction.java:62)  
at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:315)  
at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:75)  
at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:61)  
at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:303)  
at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:154)  
at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:102)  
at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:82)  
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:120)  
… 27 more  
Caused by: java.net.ConnectException: Connection timed out: connect  
at java.net.DualStackPlainSocketImpl.connect0(Native Method)  
at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)  
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)  
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)  
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)  
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)  
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)  
at java.net.Socket.connect(Socket.java:579)  
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:211)  
at com.mysql.jdbc.MysqlIO.(MysqlIO.java:298)  
… 54 more

原因是什么呢、？？

*  MySQL 的默认设置下,当一个连接的空闲时间超过8小时后,MySQL 就会断开该连接,而 c3p0 连接池则以为该被断开的连接依然有效
 *  \-

解决方案：  
1.在你的连接池上面添加atuoconnect=true加上这个，对于5以前的版本来说由于，后面的就没有用了，亲自测试。  
那么接下来你就应该在你的MySQL的安装目录的文件里面去修改，如果忘记你的MySQL的安装木目录，就更具我百度到的这个方法来找你的安装目录：

**如何你忘记MySQL的安装目录：在你的SQLyog或者你的Navicat Premium进入软件之后像平常写sql语句一样输入：select @@basedir as basePath from dual就可以查看安装路劲：**

在你的配置文件（my-default.ini或者my.ini）里面加上一句话：  
**wait\_timeout = 1814400**

2 -如果是在Spring中使用C3P0连接池，在定义datasource的时候，添加testConnectionOnCheckin和testConnectionOnCheckout和preferredTestQuery属性，  
3. 如果使用的是DBCP连接池，在定义dataDSource时添加属性validationQuery和testOnBorrow