Details
Critical Description
SoftValueSortedMap is backed by a TreeMap. All the methods in this class are synchronized. If we use this method to add/delete elements, it's ok.
But in HConnectionManager#getCachedLocation, it use headMap to get a view from SoftValueSortedMap#internalMap. Once we operate
on this view map(like add/delete) in other threads, a concurrency issue may occur.
