#10 Little memory overhead

[Paolo]

A field of CHM is needlessly nonstatic:
private final AtomicReferenceFieldUpdater<CHM,Object[]> _newkvsUpdater
That can be static (see the examples in the javadoc of that class http://java.sun.com/j2se/1.5.0/docs/api/java/util/concurrent/atomic/AtomicReferenceFieldUpdater.html\). I can't find a mention of its thread-safety, but compareAndSet operations are atomic on a single objects, it's reasonable to assume that it can manipulate multiple objects indipendently.

[Paolo]

All AtomicLongFieldUpdater members in that class are alread static, BTW.