What is the closest to ConcurrentHashMap and NavigableMap in Java?

[Jacek Furmankiewicz]

So how do existing D applications (especially the high perf ones 
in let's say the financial sector) deal with having some part of 
the data in memory and keeping it in sync with the DB source?

This must be a very common requirement for any app with realtime 
or close-to-realtime SLAs.

is there a different idiom or approach in D?