Good day.!
I am working with hibernate, ICEfaces, mysql and netebeans 6.5.1. I have reviewed some forums but I still have the same problem. I have configured hibernate hibernate.cfg.xml file with C3P0, but the communication error keeps returning. I have tested with hibernate 3.2.6 and the latest versions. I have also tested with AutoReconnect = true, but the error persists. What am I doing wrong? hibernate.cfg.xml file attached

<?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">
<hibernate-configuration>
<session-factory name="session_sgh_glass">
<!-- Database connection settings -->
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/bd?autoReconnect=true</property>
<property name="hibernate.connection.username">user</property>
<property name="hibernate.connection.password">pass</property>

<property name="dialect">org.hibernate.dialect.MySQLInnoDBDialect</property>
<property name="hibernate.current_session_context_class">thread</property>

<property name="hibernate.transaction.factory_class">org.hibernate.transaction.JDBCTransactionFactory</property>
<!-- configuration pool via c3p0-->
<property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
<property name="hibernate.connection.is-connection-validation-required">true</property>
<property name="hibernate.c3p0.acquire_increment">1</property>
<property name="hibernate.c3p0.idle_test_period">100</property>
<property name="hibernate.c3p0.timeout">100</property>
<property name="hibernate.c3p0.min_size">5</property>
<property name="hibernate.c3p0.max_size">50</property>
<property name="hibernate.c3p0.max_statements">50</property>
<property name="hibernate.c3p0.preferredTestQuery">select 1;</property>
<property name="hibernate.c3p0.testConnectionOnCheckout">true</property>
<!-- Disable second-level cache. -->
<property name="hibernate.cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
<property name="hibernate.cache.use_query_cache">false</property>
<property name="hibernate.cache.use_minimal_puts">false</property>
<property name="hibernate.max_fetch_depth">3</property>

<mapping resource=""/>
</session-factory>
</hibernate-configuration>

So what is the Error you get? post the stacktrace.

If it's your DB connection part failed, verify that you can connect without the Hibernate part.

This es el error
org.hibernate.exception.JDBCConnectionException: could not execute query
javax.faces.el.EvaluationException: org.hibernate.exception.JDBCConnectionException: could not execute query
at com.sun.faces.application.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:102)
at javax.faces.component.UICommand.broadcast(UICommand.java:380)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:475)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:756)
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
at com.icesoft.faces.webapp.http.core.JsfLifecycleExecutor.apply(JsfLifecycleExecutor.java:18)
at com.icesoft.faces.webapp.http.core.ReceiveSendUpdates.renderCycle(ReceiveSendUpdates.java:132)
at com.icesoft.faces.webapp.http.core.ReceiveSendUpdates.service(ReceiveSendUpdates.java:74)
at com.icesoft.faces.webapp.http.core.RequestVerifier.service(RequestVerifier.java:31)
at com.icesoft.faces.webapp.http.common.standard.PathDispatcherServer.service(PathDispatcherServer.java:24)
at com.icesoft.faces.webapp.http.servlet.BasicAdaptingServlet.service(BasicAdaptingServlet.java:16)
at com.icesoft.faces.webapp.http.servlet.PathDispatcher.service(PathDispatcher.java:23)
at com.icesoft.faces.webapp.http.servlet.SessionDispatcher.service(SessionDispatcher.java:53)
at com.icesoft.faces.webapp.http.servlet.SessionVerifier.service(SessionVerifier.java:26)
at com.icesoft.faces.webapp.http.servlet.PathDispatcher.service(PathDispatcher.java:23)
at com.icesoft.faces.webapp.http.servlet.MainServlet.service(MainServlet.java:131)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at com.icesoft.faces.webapp.xmlhttp.BlockingServlet.service(BlockingServlet.java:56)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:390)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:619)
Caused by: org.hibernate.exception.JDBCConnectionException: could not execute query
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:74)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at org.hibernate.loader.Loader.doList(Loader.java:2216)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2104)
at org.hibernate.loader.Loader.list(Loader.java:2099)
at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:289)
at org.hibernate.impl.SessionImpl.listCustomQuery(SessionImpl.java:1695)
at org.hibernate.impl.AbstractSessionImpl.list(AbstractSessionImpl.java:142)
at org.hibernate.impl.SQLQueryImpl.list(SQLQueryImpl.java:152)
at controlador.ServicioConfiguracion.listaMedicoNombresT(ServicioConfiguracion.java:796)
at sgh.vista.frm_buscar_medico.pp_bt_buscar_processAction(frm_buscar_medico.java:220)
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.el.parser.AstValue.invoke(AstValue.java:172)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:276)
at com.sun.faces.application.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88)
... 34 more
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet successfully received from the server was 137.820 milliseconds ago. The last packet sent successfully to the server was 1 milliseconds ago.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1122)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3056)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2942)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3485)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1960)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2114)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2696)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2105)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2264)
at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeQuery(NewProxyPreparedStatement.java:76)
at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:186)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1787)
at org.hibernate.loader.Loader.doQuery(Loader.java:674)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:236)
at org.hibernate.loader.Loader.doList(Loader.java:2213)
... 49 more
Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2503)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2953)

My best guess is that you have some stale or bad connection object in your connection pool. Try to remove all the pooling config if you don't know how to use it. If pooling is what you want, read the manual on the parameters settings.

If that is not the case, then you might have some really bad jdbc driver. Double check that and lookup your DB documentation on the error msg.