could you add a test for this ?

@stof can't really test this one since there's no way to access the visited collections...

This explains why some people have memory leaks even when using clear.

@shulcsm have you tested that this is actually the case in visitedCollections. I can't come up with a flow diagram of how this state is actually reached. The property is only set, when you call flush on the EntityManager.

@beberlei
Early return point here https://github.com/doctrine/doctrine2/blob/master/lib/Doctrine/ORM/UnitOfWork.php#L315 cause this.

To reproduce:

1. Select existing entity
2. Add new associated entities
3. Remove associated entities
4. Flush (There are no actual data, so commit returns at L315 without reaching the clear at L381)
5. Clear
   uow should be empty, visitedCollections are still there.