Why application throws 'java.util.ConcurrentModificationException' while performing a Hibernate action ?

Issue

• Why I'm getting java.util.ConcurrentModificationException in EAP 5.1 when using "Test Runner" and performing hibernate query ?

Caused by: java.util.ConcurrentModificationException
    at java.util.LinkedHashMap$LinkedHashIterator.nextEntry(LinkedHashMap.java:373)
    at java.util.LinkedHashMap$EntryIterator.next(LinkedHashMap.java:392)
    at java.util.LinkedHashMap$EntryIterator.next(LinkedHashMap.java:391)
    at org.hibernate.util.IdentityMap.entryArray(IdentityMap.java:228)
    at org.hibernate.util.IdentityMap.concurrentEntries(IdentityMap.java:89)
    at org.hibernate.event.def.AbstractFlushingEventListener.prepareEntityFlushes(AbstractFlushingEventListener.java:136)
    at org.hibernate.event.def.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:88)
    at org.hibernate.event.def.DefaultAutoFlushEventListener.onAutoFlush(DefaultAutoFlushEventListener.java:58)
    at org.hibernate.impl.SessionImpl.autoFlushIfRequired(SessionImpl.java:998)
    at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1143)
    at org.hibernate.impl.QueryImpl.list(QueryImpl.java:102)
    at com.aaa.bbb.server.persistence.dao.CshAggValueDAOBean.findSODValues(CshAggValueDAOBean.java:210)
    at com.aaa.bbb.server.persistence.facade.PersistenceFacadeEJB.getSODAggValueByFundAndEffDate(PersistenceFacadeEJB.java:872)
    ... 129 more

• In EAP 6.0, Why application is throwing java.util.ConcurrentModificationException for entity update when trying to do hibernate conditional auditing which depends on database flag? The EJB bean which does the auditing and the bean which determines the conditional flag shares same persistence unit.

Caused by: java.util.ConcurrentModificationException
    at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:859) [rt.jar:1.7.0_45]
    at java.util.ArrayList$Itr.next(ArrayList.java:831) [rt.jar:1.7.0_45]
    at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:353) [hibernate-core-4.1.6.Final-redhat-3.jar:4.1.6.Final-redhat-3]
    at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:276) [hibernate-core-4.1.6.Final-redhat-3.jar:4.1.6.Final-redhat-3]
    at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:326) [hibernate-core-4.1.6.Final-redhat-3.jar:4.1.6.Final-redhat-3]
    at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:52) [hibernate-core-4.1.6.Final-redhat-3.jar:4.1.6.Final-redhat-3]
    at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1214) [hibernate-core-4.1.6.Final-redhat-3.jar:4.1.6.Final-redhat-3]
    at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:403) [hibernate-core-4.1.6.Final-redhat-3.jar:4.1.6.Final-redhat-3]
    at org.hibernate.engine.transaction.synchronization.internal.SynchronizationCallbackCoordinatorImpl.beforeCompletion(SynchronizationCallbackCoordinatorImpl.java:104) [hibernate-core-4.1.6.Final-redhat-3.jar:4.1.6.Final-redhat-3]
    ... 40 more