ConcurrentModificationException by Business Central REST API in BPM suite

Issue

• We had the following Exception. After the Exception, a newly created process instance had an invalid behaviour (some nodes become unexpectedly active) so I had to abort the process instance and restart BPM Suite.

16:36:12,786 WARN  [com.arjuna.ats.arjuna] (http-127.0.0.1:8080-24) ARJUNA012125: TwoPhaseCoordinator.beforeCompletion - failed for SynchronizationImple< 0:ffff7f000001:-7900c1fe:5a28eab5:2b017, org.hibernate.engine.transaction.synchronization.internal.RegisteredSynchronization@34a6c813 >: javax.persistence.PersistenceException: error during managed flush
        at org.hibernate.ejb.AbstractEntityManagerImpl$CallbackExceptionMapperImpl.mapManagedFlushFailure(AbstractEntityManagerImpl.java:1515) [hibernate-entitymanager-4.2.24.Final-redhat-1.jar:4.2.24.Final-redhat-1]
        at org.hibernate.engine.transaction.synchronization.internal.SynchronizationCallbackCoordinatorNonTrackingImpl.beforeCompletion(SynchronizationCallbackCoordinatorNonTrackingImpl.java:114) [hibernate-core-4.2.24.Final-redhat-1.jar:4.2.24.Final-redhat-1]
        at org.hibernate.engine.transaction.synchronization.internal.RegisteredSynchronization.beforeCompletion(RegisteredSynchronization.java:53) [hibernate-core-4.2.24.Final-redhat-1.jar:4.2.24.Final-redhat-1]
        at com.arjuna.ats.internal.jta.resources.arjunacore.SynchronizationImple.beforeCompletion(SynchronizationImple.java:76)
        at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.beforeCompletion(TwoPhaseCoordinator.java:273)
        at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.end(TwoPhaseCoordinator.java:93)
        at com.arjuna.ats.arjuna.AtomicAction.commit(AtomicAction.java:162)
        at com.arjuna.ats.internal.jta.transaction.arjunacore.TransactionImple.commitAndDisassociate(TransactionImple.java:1211)
        at com.arjuna.ats.internal.jta.transaction.arjunacore.BaseTransaction.commit(BaseTransaction.java:126)
        at com.arjuna.ats.jbossatx.BaseTransactionManagerDelegate.commit(BaseTransactionManagerDelegate.java:75)
        at org.jboss.tm.usertx.client.ServerVMClientUserTransaction.commit(ServerVMClientUserTransaction.java:173)
        at org.drools.persistence.jta.JtaTransactionManager.commit(JtaTransactionManager.java:245) [drools-persistence-jpa-6.5.0.Final-redhat-12.jar:6.5.0.Final-redhat-12]
        at org.jbpm.services.task.persistence.TaskTransactionInterceptor.execute(TaskTransactionInterceptor.java:71) [jbpm-human-task-jpa-6.5.0.Final-redhat-12.jar:6.5.0.Final-redhat-12]
        at org.drools.core.command.impl.AbstractInterceptor.executeNext(AbstractInterceptor.java:41) [drools-core-6.5.0.Final-redhat-12.jar:6.5.0.Final-redhat-12]
        at org.drools.persistence.jta.TransactionLockInterceptor.execute(TransactionLockInterceptor.java:73) [drools-persistence-jpa-6.5.0.Final-redhat-12.jar:6.5.0.Final-redhat-12]
        at org.drools.core.command.impl.AbstractInterceptor.executeNext(AbstractInterceptor.java:41) [drools-core-6.5.0.Final-redhat-12.jar:6.5.0.Final-redhat-12]
        at org.drools.persistence.jpa.OptimisticLockRetryInterceptor.execute(OptimisticLockRetryInterceptor.java:82) [drools-persistence-jpa-6.5.0.Final-redhat-12.jar:6.5.0.Final-redhat-12]
        at org.jbpm.services.task.commands.TaskCommandExecutorImpl.execute(TaskCommandExecutorImpl.java:40) [jbpm-human-task-core-6.5.0.Final-redhat-12.jar:6.5.0.Final-redhat-12]
        at org.jbpm.services.task.impl.command.CommandBasedTaskService.execute(CommandBasedTaskService.java:157) [jbpm-human-task-core-6.5.0.Final-redhat-12.jar:6.5.0.Final-redhat-12]
        at org.jbpm.runtime.manager.impl.task.SynchronizedTaskService.execute(SynchronizedTaskService.java:851) [jbpm-runtime-manager-6.5.0.Final-redhat-12.jar:6.5.0.Final-redhat-12]
        at org.jbpm.kie.services.impl.UserTaskServiceImpl.execute(UserTaskServiceImpl.java:952) [jbpm-kie-services-6.5.0.Final-redhat-12.jar:6.5.0.Final-redhat-12]
        at org.jbpm.services.cdi.impl.UserTaskServiceCDIImpl$Proxy$_$$_WeldClientProxy.execute(UserTaskServiceCDIImpl$Proxy$_$$_WeldClientProxy.java) [jbpm-services-cdi-6.5.0.Final-redhat-12.jar:6.5.0.Final-redhat-12]
        at org.kie.remote.services.cdi.ProcessRequestBean.doTaskOperation(ProcessRequestBean.java:410) [kie-remote-services-6.5.0.Final-redhat-12.jar:6.5.0.Final-redhat-12]
        at org.kie.remote.services.cdi.ProcessRequestBean.processCommand(ProcessRequestBean.java:194) [kie-remote-services-6.5.0.Final-redhat-12.jar:6.5.0.Final-redhat-12]
        at org.kie.remote.services.cdi.ProcessRequestBean$Proxy$_$$_WeldClientProxy.processCommand(ProcessRequestBean$Proxy$_$$_WeldClientProxy.java) [kie-remote-services-6.5.0.Final-redhat-12.jar:6.5.0.Final-redhat-12]
        at org.kie.remote.services.util.ExecuteCommandUtil.restProcessJaxbCommandsRequest(ExecuteCommandUtil.java:61) [kie-remote-services-6.5.0.Final-redhat-12.jar:6.5.0.Final-redhat-12]
        at org.kie.remote.services.rest.ExecuteResourceImpl.execute(ExecuteResourceImpl.java:60) [kie-remote-services-6.5.0.Final-redhat-12.jar:6.5.0.Final-redhat-12]
        ...
Caused by: java.util.ConcurrentModificationException
        at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901) [rt.jar:1.8.0_66]
        at java.util.ArrayList$Itr.next(ArrayList.java:851) [rt.jar:1.8.0_66]
        at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:386) [hibernate-core-4.2.24.Final-redhat-1.jar:4.2.24.Final-redhat-1]
        at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:303) [hibernate-core-4.2.24.Final-redhat-1.jar:4.2.24.Final-redhat-1]
        at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:349) [hibernate-core-4.2.24.Final-redhat-1.jar:4.2.24.Final-redhat-1]
        at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:56) [hibernate-core-4.2.24.Final-redhat-1.jar:4.2.24.Final-redhat-1]
        at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1195) [hibernate-core-4.2.24.Final-redhat-1.jar:4.2.24.Final-redhat-1]
        at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:404) [hibernate-core-4.2.24.Final-redhat-1.jar:4.2.24.Final-redhat-1]
        at org.hibernate.engine.transaction.synchronization.internal.SynchronizationCallbackCoordinatorNonTrackingImpl.beforeCompletion(SynchronizationCallbackCoordinatorNonTrackingImpl.java:109) [hibernate-core-4.2.24.Final-redhat-1.jar:4.2.24.Final-redhat-1]
        ... 69 more