RFR: 8067499: G1SATBCardTableModRefBS should not inherit from CardTableModRefBSForCTRS

[Kim Barrett]

Thanks for your review, Thomas.

On Dec 17, 2014, at 9:53 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 
> Hi,
> 
> On Wed, 2014-12-17 at 01:14 -0500, Kim Barrett wrote:
>> Please review this change to G1SATBCardTableModRefBS to derive from
>> CardTableModRefBS rather than CardTableModRefBSForCTRS.
>> 
>> Note: I will need a sponsor for this change.
> [..]
>> 
>> A different way of addressing the remembered set location would have been to
>> change G1CollectedHeap to derive from CollectedHeap rather than SharedHeap,
>> and that's a change that has been suggested as a technical debt cleanup.  That
>> change would have required similar changes to G1 code, plus a number of other
>> changes.  This move of remembered set support can be viewed as a step toward
>> changing the heap hierarchy.
> 
> I talked to Tony Printezis about this once, and he mentioned that perm
> gen support has been the main reason to let G1CollectedHeap inherit from
> SharedHeap and not from CollectedHeap.

One of the odd things I noticed while working on this change is that G1CollectedHeap 
has two FlexibleWorkGang’s, one of its own and one inherited from SharedHeap.