com.mysql.jdbc.CommunicationsException MESSAGE: Communications link failure due to underlying except

[Ishant Agarwal]

Hi guys!

I am facing the issue that when I reconnect to mysql using hibernate connetion it thorws an exception like:

Last packet sent to the server was 9 ms ago.

STACKTRACE:

com.mysql.jdbc.CommunicationsException: Communications link failure due to underlying exception:

** BEGIN NESTED EXCEPTION **

java.io.EOFException

STACKTRACE:

java.io.EOFException
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1956)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2368)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2867)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1616)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1708)
at com.mysql.jdbc.Connection.execSQL(Connection.java:3255)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1293)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1428)
at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:208)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1812)
at org.hibernate.loader.Loader.doQuery(Loader.java:697)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:259)
at org.hibernate.loader.Loader.doList(Loader.java:2232)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2129)
at org.hibernate.loader.Loader.list(Loader.java:2124)
at org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:118)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1597)
at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:306)
at com.tashan.struts.utility.user_model.isValidUser(user_model.java:23)
at com.tashan.struts.action.CustomerAction.login(CustomerAction.java:59)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:269)
at org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:170)
at org.apache.struts.actions.MappingDispatchAction.execute(MappingDispatchAction.java:166)
at org.apache.struts.chain.commands.servlet.ExecuteAction.execute(ExecuteAction.java:58)
at org.apache.struts.chain.commands.AbstractExecuteAction.execute(AbstractExecuteAction.java:67)
at org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
at org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:304)
at org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
at org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:185)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:151)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:405)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:269)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:515)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:300)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
at java.lang.Thread.run(Thread.java:619)


** END NESTED EXCEPTION **

kindly help me out asap

Regards,
Ishant Agarwal

[Vijitha Kumara]

...when I reconnect to mysql using hibernate connetion it thorws an exception...

What kind of a *reconnect* is this.? Can you provide more details about the scenario?

[Ishant Agarwal]

Hi Vijitha Kumara,

The real scenario is when I started an tomcat then my application first time runs in a fine way and after logout, I am going to relogin then suddenly it lose the connection and throws me this kind of exception "com.mysql.jdbc.CommunicationsException".But after few tries it allows for login and then while working wid the application it loses the connection sometimes and again throws this exception.

I have also use a c3p0 jar for connection pooling but still unable to solve it out and I am also giving you a description of hibernate.cfg.xml

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
          "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
          "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<!-- Generated by MyEclipse Hibernate Tools. -->
<hibernate-configuration>

	<session-factory>

		<property name="hbm2ddl.auto">update</property>
		<property name="show_sql">false</property>
		<property name="dialect">
			org.hibernate.dialect.MySQLDialect
	</property>
<!--Maximum idle time for a connection (in seconds)-->
	 <property name="connection.autoReconnectForPools">true</property>
	 <property name="connection.autoReconnect">true</property>
    <property name="hibernate.c3p0.timeout">10000</property><!--
    Initial number of database connections
	--><property name="hibernate.c3p0.min_size">0</property>
	<!--Maximum number of database connections to open-->
	<property name="hibernate.c3p0.max_statements">1000</property><!--
	Idle time before a c3p0 pooled connection is validated (in seconds)
	--><property name="hibernate.c3p0.idle_test_period">10</property><!--
	Number of connections in a clump acquired when pool is exhausted
	--><property name="hibernate.c3p0.acquire_increment">30</property><!--
	Validate the connection on checkout. Recommend setting the hibernate.c3p0.idle_test_period property instead. Defaults to false
	--><property name="hibernate.c3p0.validate">true</property>
	<property name="c3p0.acquireRetryDelay">1000</property>
	<property name="c3p0.acquireRetryAttempts">60</property>
 	<property name="c3p0.breakAfterAcquireFailure">false</property>
	<property name="hibernate.connection.url"> jdbc:mysql:///customercare_0 </property>	
	<property name="hibernate.connection.username">root</property>
	<property name="hibernate.connection.password">root</property>
		<property name="connection.driver_class">
			com.mysql.jdbc.Driver
	</property>
		
		<mapping resource="CustomerCareInfo.hbm.xml" />
		<mapping resource="user.hbm.xml" />
		<mapping resource="service_keyword_details.hbm.xml" />
		
	</session-factory>

</hibernate-configuration>

Regards,
Ishant

[Vijitha Kumara]

... and after logout, I am going to relogin then suddenly it lose the connection and throws me ...

How this "logout" works, and what kind of changes done in the back end? You may need to tell more details about it. And you might get some hint form this.

[Ishant Agarwal]

I am just calling the session.invalidate() method and nothing else