Hibernate ClassCastException in GWT hosted mode only

Question

Hello and thanks for watching ;-)

Our problem/error is:

javax.persistence.PersistenceException: [PersistenceUnit: PUname] Unable to build EntityManagerFactory
...
Caused by: org.hibernate.HibernateException: Could not instantiate dialect class
...
Caused by: java.lang.ClassCastException: org.hibernate.dialect.MySQLDialect cannot be cast to org.hibernate.dialect.Dialect
...

(see full stack trace at the bottom)

It occurs in a GWT based web application using the following technologies:

• Maven
• Hibernate EntityManager /JPA
• Guice
• GWT
• GWT-P
• GWT Maven Plugin
• ...

The fact to stress is that it does work in Tomcat. Only in development mode aka hosted mode (with Jetty), using GWT Maven Plugin (with goal gwt:run), we get the ClassCastException. We were playing with Hibernate dependencies without luck (adding hibernate-validator and/or hibernate-jpa-2.0-api). The ClassCastException is thrown on startup of JPA before any service is actually used. BTW: JPA is setup using Guice:

    install(new JpaPersistModule("PUname"));
    filter("/*").through(PersistFilter.class);

It may be worth mentioning that disabling the dialect setting (in persistence.xml) creates another ClassCastException also on JPA startup:

javax.persistence.PersistenceException: [PersistenceUnit: dsmgmt] Unable to build EntityManagerFactory
...
Caused by: org.hibernate.HibernateException: Unable to instantiate specified TransactionFactory class  [org.hibernate.engine.transaction.internal.jdbc.JdbcTransactionFactory]
...
Caused by: java.lang.ClassCastException: org.hibernate.engine.transaction.internal.jdbc.JdbcTransactionFactory cannot be cast to org.hibernate.engine.transaction.spi.TransactionFactory
...

Why does it break in Jetty? What could be causing it or how can it be fixed?

File: META-INF/persistence.xml

 <persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.0" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
    <persistence-unit name="PUname" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <class>our.test.class</class>
        <properties>
            <property name="hibernate.connection.username" value="user"/>
            <property name="hibernate.connection.password" value="pass"/>
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
            <property name="hibernate.connection.url" value="jdbc:mysql://machine:3306/db"/>
            <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>
            <property name="hibernate.hbm2ddl.auto" value="update"/>
        </properties>
    </persistence-unit>
 </persistence>

Our JARs in the webapp:

       445.288 antlr-2.7.7.jar
       150.774 antlr-runtime-3.1.3.jar
         4.467 aopalliance-1.0.jar
        57.963 classmate-0.5.4.jar
       575.389 commons-collections-3.2.1.jar
        52.543 commons-exec-1.1.jar
        59.590 commons-fileupload-1.2.2.jar
       163.151 commons-io-2.1.jar
       284.220 commons-lang-2.6.jar
       313.898 dom4j-1.6.1.jar
       131.929 dsmgmt-shared-0.1-SNAPSHOT.jar
     1.006.424 ehcache-core-2.4.3.jar
       710.492 guice-3.0.jar
        36.998 guice-assistedinject-3.0.jar
        27.633 guice-persist-3.0.jar
        65.012 guice-servlet-3.0.jar
     5.004.997 gwt-servlet-2.3.0.jar
        28.339 gwtp-dispatch-server-0.6.jar
        17.184 gwtp-dispatch-server-guice-0.6.jar
        30.402 gwtp-dispatch-shared-0.6.jar
        81.426 hibernate-commons-annotations-4.0.0.Final.jar
     4.347.499 hibernate-core-4.0.0.CR6.jar
       127.259 hibernate-ehcache-4.0.0.CR6.jar
       471.832 hibernate-entitymanager-4.0.0.CR6.jar
       102.661 hibernate-jpa-2.0-api-1.0.1.Final.jar
       366.592 hibernate-validator-4.2.0.Final.jar
        70.928 jandex-1.0.3.Final.jar
       644.148 javassist-3.12.1.GA.jar
         2.497 javax.inject-1.jar
        60.542 jboss-logging-3.1.0.CR1.jar
        11.209 jboss-transaction-api_1.1_spec-1.0.0.Final.jar
       859.016 jna-3.2.3.jar
       213.781 jsch-0.1.44-1.jar
       281.579 jsoup-1.6.1.jar
       481.535 log4j-1.2.16.jar
       789.885 mysql-connector-java-5.1.18.jar
     1.351.561 org.eclipse.jgit-1.0.0.201106090707-r.jar
       601.287 pd4ml-3.80b1.jar
       149.846 pd4ml-ss-css-3.80b1.jar
        25.962 slf4j-api-1.6.4.jar
         9.748 slf4j-log4j12-1.6.4.jar
       743.673 sqljet-1.0.4.jar
       172.023 stringtemplate-3.2.jar
     1.889.196 svnkit-1.3.5.jar
       251.371 trilead-ssh2-build213-svnkit-1.3-patch.jar
        47.433 validation-api-1.0.0.GA.jar
       109.318 xml-apis-1.0.b2.jar

The full stacktrace:

javax.persistence.PersistenceException: [PersistenceUnit: PUname] Unable to build EntityManagerFactory
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:916)
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:887)
    at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:56)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:63)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:47)
    at com.google.inject.persist.jpa.JpaPersistService.start(JpaPersistService.java:94)
    at com.google.inject.persist.PersistFilter.init(PersistFilter.java:77)
    at com.google.inject.servlet.FilterDefinition.init(FilterDefinition.java:114)
    at com.google.inject.servlet.ManagedFilterPipeline.initPipeline(ManagedFilterPipeline.java:98)
    at com.google.inject.servlet.GuiceFilter.init(GuiceFilter.java:172)
    at org.mortbay.jetty.servlet.FilterHolder.doStart(FilterHolder.java:97)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:593)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1220)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:513)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:448)
    at com.google.gwt.dev.shell.jetty.JettyLauncher$WebAppContextWithReload.doStart(JettyLauncher.java:468)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
    at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
    at org.mortbay.jetty.handler.RequestLogHandler.doStart(RequestLogHandler.java:115)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
    at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
    at org.mortbay.jetty.Server.doStart(Server.java:222)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
    at com.google.gwt.dev.shell.jetty.JettyLauncher.start(JettyLauncher.java:672)
    at com.google.gwt.dev.DevMode.doStartUpServer(DevMode.java:509)
    at com.google.gwt.dev.DevModeBase.startUp(DevModeBase.java:1068)
    at com.google.gwt.dev.DevModeBase.run(DevModeBase.java:811)
    at com.google.gwt.dev.DevMode.main(DevMode.java:311)
 Caused by: org.hibernate.HibernateException: Could not instantiate dialect class
    at org.hibernate.service.jdbc.dialect.internal.DialectFactoryImpl.constructDialect(DialectFactoryImpl.java:82)
    at org.hibernate.service.jdbc.dialect.internal.DialectFactoryImpl.buildDialect(DialectFactoryImpl.java:64)
    at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:142)
    at org.hibernate.service.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:81)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:160)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:133)
    at org.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:71)
    at org.hibernate.cfg.Configuration.buildSettingsInternal(Configuration.java:2259)
    at org.hibernate.cfg.Configuration.buildSettings(Configuration.java:2255)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1724)
    at org.hibernate.ejb.EntityManagerFactoryImpl.<init>(EntityManagerFactoryImpl.java:76)
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:907)
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:887)
    at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:56)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:63)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:47)
    at com.google.inject.persist.jpa.JpaPersistService.start(JpaPersistService.java:94)
    at com.google.inject.persist.PersistFilter.init(PersistFilter.java:77)
    at com.google.inject.servlet.FilterDefinition.init(FilterDefinition.java:114)
    at com.google.inject.servlet.ManagedFilterPipeline.initPipeline(ManagedFilterPipeline.java:98)
    at com.google.inject.servlet.GuiceFilter.init(GuiceFilter.java:172)
    at org.mortbay.jetty.servlet.FilterHolder.doStart(FilterHolder.java:97)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:593)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1220)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:513)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:448)
    at com.google.gwt.dev.shell.jetty.JettyLauncher$WebAppContextWithReload.doStart(JettyLauncher.java:468)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
    at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
    at org.mortbay.jetty.handler.RequestLogHandler.doStart(RequestLogHandler.java:115)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
    at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
    at org.mortbay.jetty.Server.doStart(Server.java:222)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
    at com.google.gwt.dev.shell.jetty.JettyLauncher.start(JettyLauncher.java:672)
    at com.google.gwt.dev.DevMode.doStartUpServer(DevMode.java:509)
    at com.google.gwt.dev.DevModeBase.startUp(DevModeBase.java:1068)
    at com.google.gwt.dev.DevModeBase.run(DevModeBase.java:811)
    at com.google.gwt.dev.DevMode.main(DevMode.java:311)
 Caused by: java.lang.ClassCastException: org.hibernate.dialect.MySQLDialect cannot be cast to org.hibernate.dialect.Dialect
    at org.hibernate.service.jdbc.dialect.internal.DialectFactoryImpl.constructDialect(DialectFactoryImpl.java:73)
    at org.hibernate.service.jdbc.dialect.internal.DialectFactoryImpl.buildDialect(DialectFactoryImpl.java:64)
    at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:142)
    at org.hibernate.service.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:81)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:160)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:133)
    at org.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:71)
    at org.hibernate.cfg.Configuration.buildSettingsInternal(Configuration.java:2259)
    at org.hibernate.cfg.Configuration.buildSettings(Configuration.java:2255)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1724)
    at org.hibernate.ejb.EntityManagerFactoryImpl.<init>(EntityManagerFactoryImpl.java:76)
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:907)
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:887)
    at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:56)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:63)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:47)
    at com.google.inject.persist.jpa.JpaPersistService.start(JpaPersistService.java:94)
    at com.google.inject.persist.PersistFilter.init(PersistFilter.java:77)
    at com.google.inject.servlet.FilterDefinition.init(FilterDefinition.java:114)
    at com.google.inject.servlet.ManagedFilterPipeline.initPipeline(ManagedFilterPipeline.java:98)
    at com.google.inject.servlet.GuiceFilter.init(GuiceFilter.java:172)
    at org.mortbay.jetty.servlet.FilterHolder.doStart(FilterHolder.java:97)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:593)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1220)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:513)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:448)
    at com.google.gwt.dev.shell.jetty.JettyLauncher$WebAppContextWithReload.doStart(JettyLauncher.java:468)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
    at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
    at org.mortbay.jetty.handler.RequestLogHandler.doStart(RequestLogHandler.java:115)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
    at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
    at org.mortbay.jetty.Server.doStart(Server.java:222)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:39)
    at com.google.gwt.dev.shell.jetty.JettyLauncher.start(JettyLauncher.java:672)
    at com.google.gwt.dev.DevMode.doStartUpServer(DevMode.java:509)
    at com.google.gwt.dev.DevModeBase.startUp(DevModeBase.java:1068)
    at com.google.gwt.dev.DevModeBase.run(DevModeBase.java:811)
    at com.google.gwt.dev.DevMode.main(DevMode.java:311)

Best regards, Alexander

Answer 1

I've also faced with that problem. After some investigation, i've found out that it is special behavior of classloading of Google Eclipse Plugin + Jetty + Hibernate.

Details: In fact during running or application from eclipse the libs are loaded TWICE: first to application instance classloader and second time to web applciation classloader of jetty. Hibernate has special classloading observing during loading of sql dialects in checking classloader hierarchy and as result that instances are different.

Solution: Not real solution of this case, but i've managed to handle it with debuging GWT applcation on external server Run As -> Web Applcaition (run on external server)

Hope it helps