Hi

I've got an app where I have several places with the following code:



Are the cases where removing em.clear() calls from the code can change my app behaviour / logic?
I know that em.clear() is freeing memory but this is not the issue in my case (in my app) so forget about freeing memory in this thread.

Take care,
Adam

PS.
Sometimes I must use em.flush() (here: flush not clear) because I need to call some Oracle PL/SQL database procedures.

em.find() will now return the same entity instead of a copy. If your app relies on "==", then that's one way it could be different. Another way is if you make any changes to the entity after the flush(); before such changes would be lost; now they'll be flushed on commit() (if your flush mode is so configured). Also, operations like merge(), delete(), refresh() will obviously behave differently on attached vs. detached entities.

I'd recommend spending whatever time it takes to understand why your app used clear() in the first place and get rid of it. It reeks of "voodoo programming". My reason is that clear() breaks the normal session lifecycle. Just like you should prefer declarative @Transactional management, you should declaratively manage your session's lifecycle and flush mode. Bugs due to incorrect or misunderstood use of clear() and flush() are some of the hardest to debug and fix in my experience.