JPA pessimistic locking and JpaTemplate in Spring

Question

Is it possible to use PESIMISTIC lock option using Spring JpaTemplate methods?

I know that PESIMISTIC lock can be performed using EntityManager's methods e.g.

Account acc = em.find(Account.class, 123);

em.lock(acc, PESIMISTIC);

Answer 1

There's nothing specifically on JpaTemplate for this, but if you need access to it, you can use JpaTemplate.execute(), which takes a callback which is supplied with the EntityManager, and you can do anything you like within that callback.

A better solution, depending on your situation, might be to use Spring's transaction layer. If you annotate your DAO with @Transactional (see previous link), the JpaTransactionManager should manage entity locking for you, depending on the isolation attribute of the @Transactional attribute.

Answer 2

Depending on your default isolation level, a find followed by a lock can leave you open to consistency issues. Also, the code you posted will probably turn into two database round-trips instead of just one. It'd be preferable to do:

  em.find(Account.class, 123, PESSIMISTIC);

Or, if you're using JPA 1:

  Account acc = em.getReference(Account.class, 123);
  em.lock(acc, PESSIMISTIC);

(This isn't an answer to the question per se, but rather a comment about the OP's code. Sadly, Stack Overflow comments don't seem to support formatting.)