Jpa Eclipselink-em.find时ConcurrentModification异常

偶尔使用EntityManager.find或Query.getResultList方法对实体执行读取操作时，我遇到ConcurrentModificationException。我正在为EclipseLink使用版本2.3.2。在从帖子中获得线索后，我已经删除了显式EntityManager refresh和flush，并且行为没有变化，我仍然得到以下异常

StrackTrace看起来像这样：

Caused by: java.util.ConcurrentModificationException
        at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
        at java.util.AbstractList$Itr.next(AbstractList.java:343)
        at org.eclipse.persistence.internal.queries.InterfaceContainerPolicy.next(InterfaceContainerPolicy.java:274)
        at org.eclipse.persistence.internal.queries.ContainerPolicy.next(ContainerPolicy.java:1116)
        at org.eclipse.persistence.internal.helper.WriteLockManager.traverseRelatedLocks(WriteLockManager.java:199)
        at org.eclipse.persistence.internal.helper.WriteLockManager.acquireLockAndRelatedLocks(WriteLockManager.java:144)
        at org.eclipse.persistence.internal.helper.WriteLockManager.checkAndLockObject(WriteLockManager.java:449)
        at org.eclipse.persistence.internal.helper.WriteLockManager.traverseRelatedLocks(WriteLockManager.java:213)
        at org.eclipse.persistence.internal.helper.WriteLockManager.acquireLockAndRelatedLocks(WriteLockManager.java:144)
        at org.eclipse.persistence.internal.helper.WriteLockManager.acquireLocksForClone(WriteLockManager.java:75)
        at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.cloneAndRegisterObject(UnitOfWorkImpl.java:971)
        at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.cloneAndRegisterObject(UnitOfWorkImpl.java:929)
        at org.eclipse.persistence.internal.sessions.UnitOfWorkIdentityMapAccessor.getAndCloneCacheKeyFromParent(UnitOfWorkIdentityMapAccessor.java:181)
        at org.eclipse.persistence.internal.sessions.UnitOfWorkIdentityMapAccessor.getFromIdentityMap(UnitOfWorkIdentityMapAccessor.java:120)
        at org.eclipse.persistence.internal.sessions.IdentityMapAccessor.getFromIdentityMap(IdentityMapAccessor.java:380)
        at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.registerExistingObject(UnitOfWorkImpl.java:3899)
        at org.eclipse.persistence.queries.ObjectBuildingQuery.registerIndividualResult(ObjectBuildingQuery.java:400)
        at org.eclipse.persistence.queries.ReadObjectQuery.registerResultInUnitOfWork(ReadObjectQuery.java:780)
        at org.eclipse.persistence.queries.ObjectLevelReadQuery.checkEarlyReturn(ObjectLevelReadQuery.java:802)
        at org.eclipse.persistence.queries.DatabaseQuery.execute(DatabaseQuery.java:781)
        at org.eclipse.persistence.queries.ObjectLevelReadQuery.execute(ObjectLevelReadQuery.java:1040)
        at org.eclipse.persistence.queries.ReadObjectQuery.execute(ReadObjectQuery.java:418)
        at org.eclipse.persistence.queries.ObjectLevelReadQuery.executeInUnitOfWork(ObjectLevelReadQuery.java:1128)
        at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.internalExecuteQuery(UnitOfWorkImpl.java:2871)
        at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1516)
        at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1498)
        at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1463)
        at org.eclipse.persistence.internal.jpa.EJBQueryImpl.executeReadQuery(EJBQueryImpl.java:485)
        at org.eclipse.persistence.internal.jpa.EJBQueryImpl.getResultList(EJBQueryImpl.java:734)

---

下面是我的类在随机时间抛出ConcurrentModificationException的样子，没有明确的步骤来重现这个问题。还有其他方法

@Stateless
@Local
@EJB(name = "java:global/framework/admin/AdminServicePersistence", beanInterface = AdminrServicePersistence.class) 
public class AdminServicePersistenceImpl implements AdminServicePersistence {

    @PersistenceContext(unitName = "AdminServicePU")
    protected EntityManager em;

    protected void setEntityManager(EntityManager em) {
        this.em = em;
    } 

    @Override
    public AdminPE findAdminById(final Long id, final boolean refresh)    throws AdminServiceModuleException {
        try {
            final TypedQuery<AdminPE> query = em.createNamedQuery(AdminPE.ADMIN_BY_ID, AdminPE.class);
            query.setParameter("id", id);
            if(refresh) {
                query.setHint(QueryHints.REFRESH, HintValues.TRUE);
            }
            return executeSingleResultQuery(query);
        } catch (Exception exc) {
            throw new AdminServiceModuleException(AdminError.PERSISTENCE_QUERY_ERROR, exc);
        }        
    }
}   

@无状态
@本地的
@EJB（name=“java:global/framework/admin/AdminServicePersistence”，beanInterface=AdminServicePersistence.class）
公共类AdminServicePersistenceImpl实现AdminServicePersistence{
@PersistenceContext（unitName=“AdminServicePU”）
受保护的实体管理器em；
受保护的无效设置EntityManager（EntityManager em）{
this.em=em；
} 
@凌驾
公共AdminPE findAdminById（最终长id，最终布尔刷新）引发AdminServiceModuleException{
试一试{
final TypedQuery query=em.createNamedQuery（AdminPE.ADMIN\u BY\u ID，AdminPE.class）；
query.setParameter（“id”，id）；
如果（刷新）{
setHint（QueryHints.REFRESH，hintValue.TRUE）；
}
返回executeSingleResultQuery（查询）；
}捕获（异常exc）{
抛出新的AdminServiceModuleException（AdminError.PERSISTENCE\u QUERY\u ERROR，exc）；
}        
}
}   

您是否在多线程中使用EntityManager？我能看到这种情况的唯一方法是，如果EntityManager在不同线程之间以某种方式被重用，则每个线程都需要自己的EntityManager和查询实例。@Chris，我同意你的观点，即只有当不同的线程使用同一个EntityManager实例时，才会发生这种情况。我相信我的情况并非如此，而且这只是随机发生的。我个人希望框架“Eclipselink”能够处理这个并发问题。您是否在其他线程中使用只读实例或任何其他优化？@Chris No实际上不是。我可以说，这种情况在我删除东西的时候发生得更频繁，中间有从数据库获取数据的查询，所有这些都是单个事务的一部分。结果证明，管理实体与组实体之间存在双向多对多关系，这导致了这种异常的发生。当我禁用关系时，一切都会正常工作：（。