Concurrent request hang due to lock

I understand that in a lot of situation the concurrent request will run for a long time or hang because there will be another request or session out there is a locking it. Is there a way to simulate the lock in a test system? I am relatively new to ebs. I want to learn in this situation what steps do I need to do to find the lock or the culprit user session and kill the session. Can I find the lock in ebs front end side, or does that have to involve database queries? Gurus, please advise. Thank