7168505: (bf) MappedByteBuffer.load does not load buffer's content into memory

[Alan Bateman]

This one is somewhat assuming. MappedByteBuffer.load touches each page 
in the mapping into order to load the buffer into memory. Unfortunately 
it gets compiled into essentially a no-op server compiler (aside from 
the madvise). Someone ran into this on the Mac porting list [1]. The 
reason it isn't observed with JDK6 and older is because the load method 
is implemented in native code (we moved it into into Java as part of 
changes to sort out some alignment issues and also to address the issue 
of the file being truncated). The webrev with the proposed changes is here:

http://cr.openjdk.java.net/~alanb/7168505/webrev/

There are other ways of course.

-Alan

[1] 
http://mail.openjdk.java.net/pipermail/macosx-port-dev/2012-May/004143.html