EntityManager.lock(Object,LockModeType.WRITE) always fails

CEZimmerman · **Posted:** Fri Oct 27, 2006 2:30 am

The EntityManager.lock() method is non-functional when used with a LockModeType.WRITE. When calling the method I get the following exception trace:

My test case is simple:

Code:

        Title title1 = entityManager.find(Title.class, "1");
        EntityTransaction transaction = entityManager.getTransaction();
        transaction.begin();
        entityManager.lock(title1, LockModeType.WRITE);
        System.out.println("testEJB: " + title1.getName());
        transaction.rollback();

The problem is fairly easily traced to the fact that in AbstractEntityManagerImpl.getLockMode() a LockModeType.WRITE is always converted into a LockMode.FORCE leading to the NullPointerException in AbstractEntityPersister.lock() when getLocker() returns a null because the "lockers" attribute does not have an entry for LockMode.FORCE because the line in AbstractEntityPersister.initLockers() that creates the LockMode.FORCE entry is commented out.

Uncommenting out the line appears to fix the problem (i.e., a reasonable "SELECT id from <table> where id =? for update" is generated.

This is using Hibernate Core/Annotations/EntityManager 3.2.0 GA.

emmanuel · **Posted:** Tue Nov 07, 2006 6:18 pm

This was a bug, it is fixed in 3.2.1

darrenclarke · **Joined:** Thu Jan 25, 2007 3:36 pm **Posts:** 25

Hi

I'm also getting this same error, and I'm using versions > 3.2.1:

Code:

2007-05-14 09:36:36.950 INFO    org.hibernate.cfg.annotations.Version   Hibernate Annotations 3.3.0.GA
2007-05-14 09:36:36.963 INFO    org.hibernate.cfg.Environment   Hibernate 3.2.2
...snip...
2007-05-14 09:36:37.038 INFO    org.hibernate.ejb.Version       Hibernate EntityManager 3.3.0.GA

Is there anything else I can try?

The entity I'm trying to lock is not null and all relationships are initialized. The code that throws the exception is as follows:

Code:

EntityManager em = [snip]
em.lock( entity, LockModeType.WRITE );

The em.lock() throws:

Code:

java.lang.NullPointerException
        at org.hibernate.persister.entity.AbstractEntityPersister.lock(AbstractEntityPersister.java:1334)
        at org.hibernate.event.def.AbstractLockUpgradeEventListener.upgradeLock(AbstractLockUpgradeEventListener.java:88)
        at org.hibernate.event.def.DefaultLockEventListener.onLock(DefaultLockEventListener.java:64)
        at org.hibernate.impl.SessionImpl.fireLock(SessionImpl.java:584)
        at org.hibernate.impl.SessionImpl.lock(SessionImpl.java:576)
        at org.hibernate.ejb.AbstractEntityManagerImpl.lock(AbstractEntityManagerImpl.java:376)
        at [my calling code from this point down...]

Thanks
Darren

emmanuel · **Posted:** Tue May 15, 2007 12:56 pm

Seems like the bug is a phoenix
http://opensource.atlassian.com/projects/hibernate/browse/HHH-2613

But on the other hand why are you using LockModeType.WRITE on a non versioned entity?

darrenclarke · **Joined:** Thu Jan 25, 2007 3:36 pm **Posts:** 25

Sorry all - my bad.

Thanks Emmanuel - that was an oversight - we've added the <version /> to the ORM and it's all working now.

Darren