Hi, while trying to understand the locking internals I stumbled over DBLocking.java#L106 (in core) which throws an Exception when the same thread tries to get a lock again. The Java documentation states that ReentrantReadWriteLock should be able to handle this [1], are there any extra-conditions that make this neccessary? Regards, Max [1] "The method will return immediately if the current thread already owns the lock." http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/locks/Reentran... http://docs.oracle.com/javase/6/docs/api/java/util/concurrent/locks/Reentran...