RFR(XS): 8015244: G1: Verification after a full GC is incorrectly placed

John Cuthbertson john.cuthbertson at oracle.com
Fri May 24 16:56:40 UTC 2013

Hi Thomas,

Thanks for looking. I've fixed the minor issues you mention.


On 5/24/2013 1:09 AM, Thomas Schatzl wrote:
> Hi,
> On Wed, 2013-05-22 at 16:20 -0700, John Cuthbertson wrote:
>> Hi Everyone,
>> Can I have a couple of volunteers look over this small fix? The webrev
>> can be found at: http://cr.openjdk.java.net/~johnc/8015244/webrev.0/
>> Summary:
>> While investigating some additional verification code for "7145569: G1:
>> optimize nmethods scanning", I realized that the verification that
>> occurs after a full GC is misplaced. I think it should come after the
>> rebuilding of the RSets and verify the rebuilt RSets. Verifying the
>> RSets before the full GC is less interesting and potentially wasteful so
>> I placed the RSet verification during full GCs under control of an
>> additional diagnostic flag.
>> These aren't true performance numbers but when I ran GCOld with the new
>> flag enabled (1G heap), I saw an increase in full GC times of around 4%
>> on my workstation (VerifyBefore and VerifyAfter were both enabled).
> Looks good. Minor issues:
> - there is a typo in the description of the new flag: verfiying instead
> of verifying
> - could you spell out "rset" in the description as it is done most
> commonly so in other descriptions?
> Thanks,
>    Thomas

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