在Java EE中重新运行失败的容器管理的事务

Question

I have a situation with a legacy system which uses Java EE Bean Managed Transactions. It's getting LockAcquisitionException thrown when it's trying to retrieve something it just created.

My initial thoughts were this:

@TransactionAttribute(SUPPORTS)
public Item retrieveItem(int id) {
 Item i;
 try {
   i = em.find(Item.class, id);
 } catch (PersistenceException e) {
   if (e.getCause() instanceof LockAcquisitionException) {
     i = retrieveItem(id);
   }
 }
 return i;
}

However - when the recursive call is made, the transaction has already died - and it doesn't seem to create a new one. I've tried different TransactionAttributes , but it doesn't seem to make a difference. Also tried managing the transaction myself ( em.getTransaction() ), but that's illegal in CMT.

I'm not looking for an elegant fix - as I said, this is legacy, I just need something that will triage it until the whole thing gets replaced in a couple of months!

Cheers.

Answer 1

Try to annotate retrieveItem with @TransactionAttribute(REQUIRES_NEW) : it will then be executed in a new transaction.

Note that:

1. the the first was has been invalidated (set for rollback) and will never complete
2. during the second transaction, changes done in the first transaction are not visible anyway

So I don't know if it fits your scenario. But it's the only way I know to do an operation and commit it successfully if the original transaction has been invalidated.

Answer 2

Unfortunately the only way I can find to do this is to fix the cause of the transaction - so now I'm doing a em.flush() at the beginning of retrieveItem() . Can't wait to replace this app..