Major Description
Found that the users reference count can go into negative values, which prevents tearDownIfUnused from closing the client connection when called.
This leads to a build up of clients which have been evicted from the cache, are no longer in use, but have not been shutdown.
GC will eventually call finalize, which forcibly closes the connection and cleans up the client, but I have seen as many as several hundred open client connections as a result.
The main resource for this is caused by RetryingMetaStoreClient, which will call reconnect on acquire, which calls close. This will decrement users to -1 on the reconnect, then acquire will increase this to 0 while using it, and back to -1 when it releases it.