RFR 8215523: jstat reports incorrect values for OU for CMS GC

[Poonam Parhar]

Hello Severin,

On 8/12/19 1:22 AM, Severin Gehwolf wrote:
> Hi,
>
> On Sun, 2019-08-11 at 07:25 -0700, Poonam Parhar wrote:
>> Hello,
>>
>> The fix for this bug had to be backed out with '8227178: Backout of
>> 8215523' because it had caused timeout failures for some of the CMS
>> tests. Those failures get  resolved by adding the following check
>> before calling recalculate_used_stable() in
>> CompactibleFreeListSpace::allocate():
>>
>> 1387   // During GC we do not need to recalculate the stable used value for
>> 1388   // every allocation in old gen. It is done once at the end of GC instead
>> 1389   // for performance reasons.
>> 1390   if (!CMSHeap::heap()->is_gc_active()) {
>> 1391     recalculate_used_stable();
>> 1392   }
>> 1393
>>
>> Please review the updated webrev:
>> http://cr.openjdk.java.net/~poonam/8215523/webrev.02/
> +  // Returns monotonically increasing stable used space bytes for CMS.
> +  // This is required for jhat and other memory monitoring tools
>
> jhat has been removed a while ago: jhat => jstat
A typo from the previous changes. Will fix it.
>
> Aside: Why has there not been a new bug filed "Redo: jstat reports
> incorrect values for OU for CMS GC". It's confusing to look at JDK-
> 8215523, see it resolved and mention a pushed commit in the comments.
> Isn't that what's usually been done for backouts?
My mistake. I will file another bug and will then re-submit the review 
request.

Thanks,
Poonam
> Thanks,
> Severin
>