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mcassidygamma
 Post subject: Wildfly Clustering and hibernate
PostPosted: Wed Aug 17, 2016 4:23 am 
Newbie

Joined: Wed Aug 17, 2016 4:15 am
Posts: 2
I'm setting up a cluster of wildfly instances to run my application. It's using hibernate for its persistance.

I'm working from the infinispan config from standalone-ha.xml, jgroups I've altered to use tcp ping instead as I cannot use multicast in my environment.

Session replication is working perfectly, my mod_jk load balancer is not using sticky sessions and both of the servers in the cluster (only testing with 2) are serving up pages successfully.

I am experiencing an intermittent issue with hibernate however:
Code:
2016-08-16 10:14:47,518 INFO  [stdout] (default task-8) Caused by: java.lang.NullPointerException: null

2016-08-16 10:14:47,518 INFO  [stdout] (default task-8)     at org.hibernate.collection.internal.AbstractPersistentCollection.openTemporarySessionForLoading(AbstractPersistentCollection.java:274)

2016-08-16 10:14:47,518 INFO  [stdout] (default task-8)     at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:201)

2016-08-16 10:14:47,519 INFO  [stdout] (default task-8)     at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:546)

2016-08-16 10:14:47,519 INFO  [stdout] (default task-8)     at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:133)

2016-08-16 10:14:47,519 INFO  [stdout] (default task-8)     at org.hibernate.collection.internal.PersistentBag.iterator(PersistentBag.java:277)

I'm using wildfly 10, which is running hibernate 5.

Source of the class in question: http://grepcode.com/file/repo1.maven.or ... ding%28%29

The class is used for lazy loaded lists (with a one to many relationship), among other things.

Here's some of the code:
Code:
@Table(name = "[User]")
@Entity
public class User extends CommonDomainBase
{

    @OneToMany(cascade = CascadeType.REMOVE, orphanRemoval = true, mappedBy = "user", fetch = FetchType.LAZY)
    private List<UserSearchingPreference> searchingPreferences;

    public List<UserSearchingPreference> getSearchingPreferences()
    {
        return searchingPreferences;
    }
}

From what I can see, the sessionFactoryUuid will be serialised when. So if the User is loaded on server 1, replicated to server 2, and a different request which hits server 2 attempts to call getSearchingPreferences() the sessionFactoryUuid which relates to the hibernate session on server 1 cannot be used to lookup the session on server 2, because it won't exist.

Is anyone able to confirm if I'm correct in my assumption and suggest a solution?

I'm not sure whether this is some hibernate configuration that needs adjusting, or if I should be in some way detaching objects before they are replicated.
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smarlow@redhat.com
 Post subject: Re: Wildfly Clustering and hibernate
PostPosted: Mon Aug 29, 2016 10:31 am 
Red Hat Associate
Red Hat Associate

Joined: Wed Apr 18, 2012 9:06 pm
Posts: 6
Great find! IMO, the fix should likely be in org.hibernate.collection.internal.AbstractPersistentCollection should also use session.getFactory().getName() for clustering, as session factory name is typically used in clustered environments instead of the UUID:

Code:
   private String sessionFactoryUuid;
   private String sessionFactoryName;

   protected void prepareForPossibleLoadingOutsideTransaction() {
      if ( session != null ) {
         allowLoadOutsideTransaction = session.getFactory().getSessionFactoryOptions().isInitializeLazyStateOutsideTransactionsEnabled();

         if ( allowLoadOutsideTransaction && sessionFactoryName == null ) {
            sessionFactoryName = session.getFactory().getName();
         else if ( allowLoadOutsideTransaction && sessionFactoryUuid == null ) {
            sessionFactoryUuid = session.getFactory().getUuid();
         }
      }
   }

   private SharedSessionContractImplementor openTemporarySessionForLoading() {
      if ( sessionFactoryUuid == null && sessionFactoryName == null ) {
         throwLazyInitializationException( "SessionFactory UUID or name is not known to create temporary Session for loading" );
      }

      final SessionFactoryImplementor sf = (SessionFactoryImplementor)
                                sessionFactoryName != null ? SessionFactoryRegistry.INSTANCE.getNamedSessionFactory(sessionFactoryName) :
            SessionFactoryRegistry.INSTANCE.getSessionFactory( sessionFactoryUuid );
      final SharedSessionContractImplementor session = (SharedSessionContractImplementor) sf.openSession();
      session.getPersistenceContext().setDefaultReadOnly( true );
      session.setFlushMode( FlushMode.MANUAL );
      return session;
   }


Please create a HHH jira for the above change, I think the title should be something like "AbstractPersistentCollection lazy handling in a cluster" and reference this forum post, as well as have your description of the symptoms.

Scott
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smarlow@redhat.com
 Post subject: Re: Wildfly Clustering and hibernate
PostPosted: Mon Sep 05, 2016 9:15 pm 
Red Hat Associate
Red Hat Associate

Joined: Wed Apr 18, 2012 9:06 pm
Posts: 6
The link for creating a HHH jira to track this issue is https://hibernate.atlassian.net/browse/HHH. I prefer to let you create the jira, so you get credit for reporting the issue. Please post a link here to the HHH jira that you create, so others can follow it.
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mcassidygamma
 Post subject: Re: Wildfly Clustering and hibernate
PostPosted: Wed Sep 07, 2016 8:06 am 
Newbie

Joined: Wed Aug 17, 2016 4:15 am
Posts: 2
Thanks for the reply. I've create a new issue: https://hibernate.atlassian.net/browse/HHH-11091
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