Suggested fix for JDK-4724038 (Add unmap method to MappedByteBuffer)

[Dawid Weiss]

> I think it would be best to leave to the application to decide and
> implement the tracking and also triggering GC at times when it approaches
> the limit.

I disagree. The GC -- when and how it is triggered -- should be
transparent to the application. We don't want to manage GC, we want to
(truly) release the resources we allocated (and we know when they are
no longer needed).

What you suggest is essentially managing GC from application level. I
don't think it's the right approach to solve the problem.

Dawid