RFR: 8200557: OopStorage parallel iteration scales poorly

[Kim Barrett]

> On May 2, 2018, at 5:42 PM, coleen.phillimore at oracle.com wrote:
> 
> 
> Changes look good.

Thanks.

> 
> I like the new comments.  I still think pointing out that these are forward declarations and not what they are used for here is not very interesting, though.  A short 1/2 liner as suggested would be better in case one doesn't need to read the rest of the code.
>> […]
>> 
> Thanks for moving the comments into the implementation.  I like where they are now.
> 
> If you decide to update any more comments, I don't need to see another webrev.

For the record, I'm making this additional change:

-  class Block;                  // Forward decl; defined in .inline.hpp file.
-  class BlockArray;             // Forward decl; defined in .inline.hpp file.
-  class BlockEntry;             // Forward decl; defined in .inline.hpp file.
+  class Block;                  // Fixed-size array of oops, plus bookkeeping.
+  class BlockArray;             // Array of Blocks, plus bookkeeping.
+  class BlockEntry;             // Provides BlockList links in a Block.

I really don't remember why the old comments were as they were; that's
not my normal commenting style.  Maybe someone asked for something
like that in pre-review?  But I can't think who would have, or find
any record of such.  Oh well.