Anagrams Kata (Was: ConcurrentHashMap/ConcurrentMap/Map.compute)

[Brian Goetz]

> 1. "collectUnordered" is important.  If it is replaced by "collect" then the program will appear to hang for many seconds before finally producing output.

Yes.  We expected that concurrent collection would be faster for simple group-by, though also we have a lot of tuning to do in the non-concurrent collection.