Distributed locking written in a failsafe manner. If the person holding the lock dies, there isn't going to be chaos, rather it's going to be possible to use the lock still. Additionally, multiple threads of the same host can try and get the lock without problems. Tried and Tested. CAVEAT: Only 1 lock can exist in the system, and the locking mechanism is slow, so the best thing to do is to use it very sparingly.