Queries related to Toplink ClientSession and UnitOfWork

Question

I'm facing with a memory leak issue and was trying to investigate it by looking at the log files. Here, are few things I saw which I thought are potential reason but could not really link with a memory leakage -
Code looks like -
Session session = DBManager.acquireSession();
UnitOfWork uow = session.acquireUnitOfWork();
...some processing/work with UnitOfWork but no release
The program navigates to a different path without releasing UnitOfWork or Session.
When I look at the log files I see that the Sessions are getting garbage collected (I see log entries that say Session has been released) even though after an hour or so. I guess I’m able to see that Sessions are being garbage collected as finalize() method of ClientSession internally makes a call to ClientSession.release() method. However, I never see UnitOfWork being garbage collected or I don’t know as there are no corresponding log entries.
Queries –
1) Would these un-released UnitOfWork hold onto some memory causing a Memory leak??
2) What happens to UOWs that are acquired from a Session that has been eventually garbage collected?? Will garbage collection of Session inturn cause garbage collection of UOWs??
I also have a code like –
Session session = DBManager.acquireSession();
.. Do some work with Session
session.release();
..after some time use the same Session reference to do more work like
session.readObject();
Over here I see that Session can still be used after it has been released with no problem. But I guess calling a release() next time on it won’t have any impact, is that true?? Also, now this would be a hanging Session as it was not released, right??
Eagerly waiting for some help!

Answer 1

Simpler usage is to link UnitOfWork with the JTA transaction, then when JTA transaction commit or rollback the UnitOfWork remove will be called, and UOW will do the same on its parent ClientSession.
In Java, unlike Microsoft COM, instances will be garbage collected if reference each other like a cycle.
There is no side effect of not calling remove on UnitOfWork, but if not calling on ClientSession, and the ClientSession hold a DB connection from a pool, the pool is left with a missing connection, the act of adding back the connection to the pool is not something done by GC alone.