JPA悲观锁不工作

Question

我使用Spring Boot、JPA、Oracle12C和下面的类型化查询来选择要处理的“新”项。一旦我选择了一个“新的”项目，我会更新它的状态，这样它就不再有资格被选择，但我发现了一个并发问题，同样的项目会被选中。

我读到here，我需要在查询上设置一个'LockModeType.PESSIMISTIC_WRITE‘，以防止其他线程选择相同的行，但它似乎不起作用。

我是否遗漏了下面的内容，或者我是否需要另一种配置来防止并发线程从我的表中检索相同的行？问题出在锁级别还是实体管理器没有得到更新/刷新？

我的@Transactional服务：

@Override
@Transactional(isolation = Isolation.READ_COMMITTED, rollbackFor=RuntimeException.class)
public MyObject retrieveItemByStatus(StatusEnum status) {
    return myRepository.retrieveItemByStatus(status);
}

我的存储库层中的查询：

@Override
public MyObject retrieveItemByStatus(StatusEnum status) {

    String sql = "SELECT t FROM myTable t WHERE status = :status ORDER BY id ASC";      
    try {
        TypedQuery<MyObject> query = em.createQuery(sql, MyObject.class).setParameter("status", status);
        query.setLockMode(LockModeType.PESSIMISTIC_WRITE);
        query.setFirstResult(0);
        query.setMaxResults(1);
        MyObject myObject = (MyObject) query.getSingleResult();
        if (myObject != null) {
            myObject.setStatus(StatusEnum.IN_PROGRESS);
            MyObject myUpdatedObject = em.merge(myObject);                              
            return myUpdatedObject;
        }
    } catch (IllegalArgumentException iae) {
        //some logging
    } catch(NoResultException nrf) {            
        //some logging
    } catch(Exception ex) {
        //some logging
    }       
    return null;
}

Answer 1

我可以证实这一点。我有几个锁定模式测试与H2数据库，所有工作都如预期。这两种悲观锁定模式在与Oracle数据库的组合中都不能正常工作。因此，问题是:这段代码有什么问题？

对于Oracle，这些并发代码中的两次执行会产生相同的数据，尽管第一次应该会阻塞第二次：

// Every Thread gets its own Hibernate session:
final Session session = HibernateSessionHolder.get();

session.getTransaction().begin();
final List<EventDeliveryDataDB> eddList = 
        session.createCriteria(EventDeliveryDataDB.class)
            .setLockMode(LockMode.PESSIMISTIC_WRITE) // with READ the same
            .add(eq("progress", NEW))
            .list();
eddList.stream().forEach(eddElem -> eddElem.setProgress(IN_PROGRESS));
session.getTransaction().commit();

休眠日志：

Hibernate: select this_.DD_ID as DD_ID1_2_0_, this_.CHANNEL_NAME as CHANNEL_NAME2_2_0_, this_.created as created3_2_0_, this_.DELIVERY_TIME as DELIVERY_TIME4_2_0_, this_.ERROR_CODE as ERROR_CODE5_2_0_, this_.ERROR_MESSAGE as ERROR_MESSAGE6_2_0_, this_.EVENT_ID as EVENT_ID7_2_0_, this_.MAX_RETRIES as MAX_RETRIES8_2_0_, this_.PROGRESS as PROGRESS9_2_0_, this_.PROGRESS_ID as PROGRESS_ID10_2_0_, this_.RECIPIENT_CRID as RECIPIENT_CRID11_2_0_, this_.RETRY_COUNTER as RETRY_COUNTER12_2_0_, this_.RETRY_TIME as RETRY_TIME13_2_0_, this_.updated as updated14_2_0_ from HR.NOS_DELIVERY_DATA this_ where this_.PROGRESS=?
Hibernate: select this_.DD_ID as DD_ID1_2_0_, this_.CHANNEL_NAME as CHANNEL_NAME2_2_0_, this_.created as created3_2_0_, this_.DELIVERY_TIME as DELIVERY_TIME4_2_0_, this_.ERROR_CODE as ERROR_CODE5_2_0_, this_.ERROR_MESSAGE as ERROR_MESSAGE6_2_0_, this_.EVENT_ID as EVENT_ID7_2_0_, this_.MAX_RETRIES as MAX_RETRIES8_2_0_, this_.PROGRESS as PROGRESS9_2_0_, this_.PROGRESS_ID as PROGRESS_ID10_2_0_, this_.RECIPIENT_CRID as RECIPIENT_CRID11_2_0_, this_.RETRY_COUNTER as RETRY_COUNTER12_2_0_, this_.RETRY_TIME as RETRY_TIME13_2_0_, this_.updated as updated14_2_0_ from HR.NOS_DELIVERY_DATA this_ where this_.PROGRESS=?
Hibernate: select DD_ID from HR.NOS_DELIVERY_DATA where DD_ID =? for update
Hibernate: select DD_ID from HR.NOS_DELIVERY_DATA where DD_ID =? for update
Hibernate: update HR.NOS_DELIVERY_DATA set CHANNEL_NAME=?, created=?, DELIVERY_TIME=?, ERROR_CODE=?, ERROR_MESSAGE=?, EVENT_ID=?, MAX_RETRIES=?, PROGRESS=?, PROGRESS_ID=?, RECIPIENT_CRID=?, RETRY_COUNTER=?, RETRY_TIME=?, updated=? where DD_ID=?
Hibernate: update HR.NOS_DELIVERY_DATA set CHANNEL_NAME=?, created=?, DELIVERY_TIME=?, ERROR_CODE=?, ERROR_MESSAGE=?, EVENT_ID=?, MAX_RETRIES=?, PROGRESS=?, PROGRESS_ID=?, RECIPIENT_CRID=?, RETRY_COUNTER=?, RETRY_TIME=?, updated=? where DD_ID=?

Answer 2

AFAIK你不能在oracle中阻止“读取”...悲观锁对应于不会阻塞其他select语句的select for update ...它只会强制它读取旧版本的数据(在select for update运行之前)……它将只阻塞其他select for update语句(因此其他查询具有悲观锁)