Per my other convo, I now see what you mean - I hadn't remembered the "infinite linked list" issue with map resizing.  I'm thinking of ripping out guts from Guava's mapmaker or cachebuilder which I was trying to avoid, but may be necessary.  Any altnernative suggestions?  I know of no other "WeakConcurrentHashMap" and "ConcurrentLinkedHashMap" impls.