What is the closest to ConcurrentHashMap and NavigableMap in Java?

[Jacek Furmankiewicz]

Yes, that is what they say in Go...but it doesn't scale either. 
:-)

I had the exact same discussion on the Go forums a while back and 
the conclusion was basically the same...roll your own maps with 
RW locks:

https://groups.google.com/forum/?fromgroups#!searchin/golang-nuts/furmankiewicz/golang-nuts/jjjvXG4HdUw/ffWytKQ7X9YJ

But...at the end someone actually built lock-free data structures 
in Go out of this:

https://github.com/zond/gotomic