使用JTA的Eclipselink找不到新插入的实体，并引发重复键异常

Question

public Eom() {
}


@Id
@Column(unique=true, nullable=false, length=150)
public String getProjectname() {
    return this.projectname;
}

public void setProjectname(String projectname) {
    this.projectname = projectname;
}

@stateless@singleton公共类EomDao实现EomDaoLocal{

private @PersistenceContext(unitName = "emiClearQuestAdapterPersistancy")
EntityManager em;

@Override
public void storeEom(Eom eom) {
    em.persist(eom);
}

@Override
public void updateEom(Eom eom) {
    em.merge(eom);
}

@Override
public void deleteEom(Eom eom) {
    em.remove(eom);
}

@Override
public Eom getEomByProjectName(String projectName) throws NotFoundException {
    em.getEntityManagerFactory().getCache().evictAll();
    return em.find(Eom.class, projectName);
}

@Override
public boolean existsEom(String projectName) {
    try {
        if (this.getEomByProjectName(projectName) != null) {
            return true;
        } else {
            return false;
        }
    } 
    catch (NotFoundException e) {
        return false;
    }
}

}

还有门面

@Stateless@Singleton公共类DefectListFacade实现DefectListFacadeLocal{

private @EJB
DefectDaoLocal defectdao;
private @EJB
EomDaoLocal eomdao;

@Override
public void insertdefect(CQDefect defect) {

    String projectName = defect.getFehlerprojektnummer().getLabel();

    Eom eom = new Eom();
    eom.setProjectname(projectName);

    Defect domaindefect = new Defect();
    List<Defect> defectlist = new ArrayList<Defect>();

    transferJsonToDomain(domaindefect, defect);
    domaindefect.setEom(eom);
    defectlist.add(domaindefect);
    eom.setDefects(defectlist);

    eomdao.storeEom(eom);

    Logger.getLogger(DefectListFacade.class.getName()).info(
            "EOM -- INSERTED " + eom.getProjectname());
}

@Override
public void updatedefect(CQDefect defect) {

    String projectName = defect.getFehlerprojektnummer().getLabel();

    Logger.getLogger(DefectListFacade.class.getName()).info(
                "EOM -- UPDATED " + projectName);
}

这是我的留言

@Override
public void receiveMessage(BaseMessage message) {
    if (message instanceof FehlerMessage) {
        FehlerMessage fehlermsg = (FehlerMessage) message;
        if (eomdao.existsEom(fehlermsg.getEom())) {
            defectlistfacade.updatedefect(fehlermsg.getFehler());
        } else {
            defectlistfacade.insertdefect(fehlermsg.getFehler());
        }
        Logger.getLogger(FehlerMessageReceiver.class.getName()).fine(
                fehlermsg.getEom() + " - "
                        + fehlermsg.getFehler().getFehler_Titel());
        monitoring.notifyEMDBMessageReceive(BusType.Base,
                message.getTypeIdentifier(), message.getSize());
    }
}

按照克里斯说的去做之后，我发现了正在发生的事情。这是一种种族条件。

[#2014-03-27T11:22:39.051+0100InfoglassFish3.1.2com.generali.tools.myemi.components.clearquest.crud.facade.defectListFacade_Threadid=2603；_ThreadName=Thread-10；EOM--已插入PRJ-00359#]

[#2014-03-27T11:22:39.051+0100warningglassfish3.1.2javax.enterprise.system.core.transaction.com.sun.jts.jta_threadid=2605；_threadname=thread-10；jts5054:完成后出现意外错误

本地异常堆栈：异常[EclipseLink-4002]（Eclipse Persistence Services-2.3.2.V20111125-R10461):org.Eclipse.Persistence.exceptions.DatabaseException内部异常:com.mysql.jdbc.exceptions.jdbc4.mysqlintegrityConstraintViolationException：项“primary”的条目“PRJ-00359”重复错误代码：1062调用：INSERT INTO eom(PROJECTNAME)值（？）绑定=>[1个参数绑定]

有两个JMS消息，它们以相同的EOM名称（主键）紧挨着来，线程号2605首先插入EOM。但是还有一个线程的编号是2603,它也在第一次插入之后插入相同的主键。无论如何，第二个线程不知道第一个插入。

现在的问题是，我如何锁定第二个插入等待第一个完成？