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jBPM session persistence - "Removing a detached instance" encountered under load / concurrency
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created by <a href="https://community.jboss.org/people/xmrk">Mark Egan</a> in <i>jBPM</i> - <a href="https://community.jboss.org/message/778981#778981">View the full discussion</a>
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<div class="jive-rendered-content"><p>I'm encountering an exception with jbpm-persistence-jpa when performing load testing on an application-embedded jBPM.  The stack trace is:</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Caused by: java.lang.IllegalArgumentException: Removing a detached instance org.drools.persistence.info.WorkItemInfo#234</p><p>     at org.hibernate.ejb.event.EJB3DeleteEventListener.performDetachedEntityDeletionCheck(EJB3DeleteEventListener.java:67) [hibernate-entitymanager-4.0.1.Final.jar:4.0.1.Final]</p><p>     at org.hibernate.event.internal.DefaultDeleteEventListener.onDelete(DefaultDeleteEventListener.java:107) [hibernate-core-4.0.1.Final.jar:4.0.1.Final]</p><p>     at org.hibernate.event.internal.DefaultDeleteEventListener.onDelete(DefaultDeleteEventListener.java:74) [hibernate-core-4.0.1.Final.jar:4.0.1.Final]</p><p>     at org.hibernate.internal.SessionImpl.fireDelete(SessionImpl.java:822) [hibernate-core-4.0.1.Final.jar:4.0.1.Final]</p><p>     at org.hibernate.internal.SessionImpl.delete(SessionImpl.java:801) [hibernate-core-4.0.1.Final.jar:4.0.1.Final]</p><p>     at org.hibernate.ejb.AbstractEntityManagerImpl.remove(AbstractEntityManagerImpl.java:883) [hibernate-entitymanager-4.0.1.Final.jar:4.0.1.Final]</p><p>     at org.drools.persistence.jpa.JpaPersistenceContext.remove(JpaPersistenceContext.java:54) [drools-persistence-jpa-5.5.0.Final.jar:5.5.0.Final]</p><p>     at org.drools.persistence.jpa.processinstance.JPAWorkItemManager.completeWorkItem(JPAWorkItemManager.java:123) [drools-persistence-jpa-5.5.0.Final.jar:5.5.0.Final]</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>I'm using 5.4.0.Final (however I observed the same behavior in 5.3.0.Final and 5.4.0.CR1).  The application server is JBoss AS 7.  I'm using MySQL InnoDB having row-locking enabled.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>The process calls EJBs within separate WorkItemHandlers.  Here's the basic process:</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>1) start process,</p><p>2) call a local, no-interface EJB (injected with @Inject) and persist a domain object (using a separate persistence context),</p><p>3) lookup another EJB (using InitialContext.doLookup) and perform some synchorous work,</p><p>4) end process.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>I'm initiating the process from a REST endpoint.  The jBPM session.startProcess(...) occurs in a Local EJB exposed service.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>The load test calls the REST endpoint.  I'm using jMeter.  The thread group only consists of 2 threads.  There is a short ramp-up.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Here's a rundown of my observations:</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>During ramp-up where the process service is a single thread, no issues are observed.  Once the second thread spins up, the exception is received on all subsequent calls.  The WorkItemInfo which fails to be removed is for step #2 (the local EJB call to a separate persistence service).  If I remove the third step from the definition, the issue is not observed.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Here's my Environment for the JPAKnowledgeService.newStatefulKnowledgeSession(...).  </p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>@Produces</p><p>public Environment getEnvironment() {</p><p>    Environment env = KnowledgeBaseFactory.newEnvironment();</p><p>    env.set(EnvironmentName.ENTITY_MANAGER_FACTORY, emf);</p><p>    env.set(EnvironmentName.TRANSACTION_MANAGER, new ContainerManagedTransactionManager());</p><p>    env.set(EnvironmentName.PERSISTENCE_CONTEXT_MANAGER, new JpaProcessPersistenceContextManager(env));</p><p>    return env;</p><p>}</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>I'm only using a session once and dispose of it after a single process completes.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>I'm setting the following for my persistence context:</p><p>hibernate.transaction.factory_class=org.hibernate.transaction.CMTTransactionFactory</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>I understand that what I'm encountering could be related to general container handled transactions across my EJB calls, but I wanted to start with the jBPM community.  I had already investigated the transaction handling on those EJB calls and wasn't able to resolve the issue using various @TransactionAttribute or alterations to the persistence context's properties.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p><span>I also reviewed the persistence chapter in the 5.4 User Guide: </span><a class="jive-link-external-small" href="http://docs.jboss.org/jbpm/v5.4/userguide/ch.core-persistence.html" target="_blank">http://docs.jboss.org/jbpm/v5.4/userguide/ch.core-persistence.html</a><span>, as well as the Multi-Threading section: </span><a class="jive-link-external-small" href="http://docs.jboss.org/jbpm/v5.4/userguide/ch.core-basics.html#d0e2358" target="_blank">http://docs.jboss.org/jbpm/v5.4/userguide/ch.core-basics.html#d0e2358</a><span>.</span></p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Any help is appreciated.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Thanks,</p><p>-mark</p></div>
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