Judging from the javadoc in HConnectionManager, sharing connections across multiple clients going to the same cluster is supposedly a good thing. However, the fact that there is a one-to-one mapping between a configuration and connection instance, kind of works against that goal. Specifically, when you create HTable instances using a given Configuration instance and a copy thereof, we end up with two distinct HConnection instances under the covers. Is this really expected behavior, especially given that the configuration instance gets cloned a lot?
Here, I'd like to play devil's advocate and propose that we "deep-compare" HBaseConfiguration instances, so that multiple HBaseConfiguration instances that have the same properties map to the same HConnection instance. In case one is "concerned that a single HConnection is insufficient for sharing amongst clients", to quote the javadoc, then one should be able to mark a given HBaseConfiguration instance as being "uniquely identifiable".
Note that "sharing connections makes clean up of HConnection instances a little awkward", unless of course, you apply the change described in