Do I have to close() every EntityManager?

Question

I have just started migrating my homegrown persistence framework to JPA.

Given that the persistence frameworks hide a lot of the plumbing, I\'m interested in knowing

Answer 1

You should.

Frameworks have no idea how you intend to use the EM, so they cannot close it (except, may be, on finalization, which is not guaranteed). Yes, not closing them would create a resource leak.

The idea is the same as "always close java.sql.Connection" (despite some data sources have settings to close them automatically by inactivity) or "always close Hibernate session".

Besides, if you plan to write portable code, you shouldn't rely on specific JPA provider "being smart" -- other may fail to close the EM in time.