Provided hibernate does not see persistence.xml loaded by custom classloader

[jsvitak]

Hello,

I don't know if this is the best place to ask this question, but I think it's a problem related to classloading in EAP 6. I am working on a jBPM plugin for Jenkins and jBPM uses Hibernate for persistence. I have configured my project to use Hibernate 4 provided by EAP 6. However Hibernate 4 cannot see persistence.xml file which is used in the plugin. I assume the problem is that Jenkins uses several classloaders and one of them is for the plugins (hudson.PluginManager.uberClassLoader). Plugins are not placed inside Jenkins .war file, but as .hpi (.jar) files in ~/.jenkins/plugins. So Hibernate 4 does not know about this classloader and cannot see the persistence.xml. Can you please tell me how to configure EAP or Hibernate to look for persistence.xml in Jenkins uberClassLoader?

Here is the output from EAP 6 server log:

15:50:18,993 INFO  [org.hibernate.ejb.Ejb3Configuration] (Executor #0 for master : executing test-timer #12) HHH000318: Could not find any META-INF/persistence.xml file in the classpath

Jenkins web console says just this:

FATAL: No Persistence provider for EntityManager named org.jbpm.persistence.jpa

javax.persistence.PersistenceException: No Persistence provider for EntityManager named org.jbpm.persistence.jpa

at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:69)

at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:47) 

at org.jenkinsci.plugins.jbpm.SessionUtil.getPersistedSession(SessionUtil.java:102) 

at org.jenkinsci.plugins.jbpm.SessionUtil.getStatefulKnowledgeSession(SessionUtil.java:91) 

at org.jenkinsci.plugins.jbpm.JbpmUrlResourceBuilder.perform(JbpmUrlResourceBuilder.java:104) 

at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:19) 

at hudson.model.AbstractBuild$AbstractRunner.perform(AbstractBuild.java:697) 

at hudson.model.Build$RunnerImpl.build(Build.java:178) 

at hudson.model.Build$RunnerImpl.doRun(Build.java:139) 

at hudson.model.AbstractBuild$AbstractRunner.run(AbstractBuild.java:467) 

at hudson.model.Run.run(Run.java:1404) 

at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46) 

at hudson.model.ResourceController.execute(ResourceController.java:88) 

at hudson.model.Executor.run(Executor.java:238)

[smarlow]

Could you debug and set a breakpoint in javax.persistence.Persistence.createEntityManagerFactory line 62 and look at the contents of the "providers" variable. 

[jsvitak]

I have debugged AS using Eclipse and providers variable contains one element - an instance of HibernatePersistence. I have tested my plugin (without debugging) also with latest AS7 nightly build (2012-11-20) with the same problem.

[jkronegg]

I've got a similar error message under JBoss EAP5/AS6 when using a custom persistence provider: the custom persistence provider could not be found even if it was listed in the META-INF/services/javax.persistence.spi.PersistenceProvider along with the org.hibernate.persistence.HibernatePersistence. The javax.persistence.Persistence.providers variable contains only one element (I suspect this is the persistence provider provided by the application server).

I've solved this issue by calling by javax.persistence.Persistence.findAllProviders by introspection before the Persistence.createEntityManagerFactory is called (because this methods calls findAllProviders only if the providers collection is empty).

[smarlow]

Jiri,

in AS7/EAP6 and greater, depending on the Hibernate version (AS8 will switch to including Hibernate 4.3.x for JPA 2.1), there are custom ways to bootstrap the Hibernate session factory that allow classloader(s) to be passed in.  The Hibernate documentation is a good source for guidance. 

You might want to encapsulate your use of BootstrapServiceRegistryBuilder, in case it changes (I think there are some changes coming in Hibernate 4.3.x).

Julien, http://docs.oracle.com/javaee/6/api/javax/persistence/Persistence.html doesn't mention the findAllProviders(), I don't think that is in all implementations of javax.persistence.Persistence (doesn't appear to be in the recent Hibernate javax.persistence.Persistence implementation). 

Scott

[jkronegg]

@Scott: that's true, findAllProviders() does not exist in all implementations. We use this trick as a workaround against a specific implementation (such as this one) which caches the providers. This issue would most probably not occur in recent implementations (such as this one). We decided to live with the workaround at this time...