RFR (XS): -8064865: Remove the debug funciontality RotateCMSCollectionTypes for CMS
jon.masamitsu at oracle.com
Fri Nov 14 21:58:43 UTC 2014
On 11/13/2014 11:09 PM, Bengt Rutisson wrote:
> On 2014-11-14 08:05, Bengt Rutisson wrote:
>> Hi all,
>> Can I have a couple of reviews for this small change to remove a
>> debug flag from CMS?
> I should have pointed out that this patch is based on top of the patch
> for JDK-8064702 that is currently out for review.
Change looks good. Reviewed.
>> During the review of "8064702: Remove the CMS foreground collector"
>> it was discussed how to handle the RotateCMSCollectionTypes feature.
>> It was suggested to remove this feature in a separate change. This is
>> the change to remove that feature.
>> From the bug description:
>> The RotateCMSCollectionTypes flag is used in CMS to rotate between
>> the three different kinds of collections of the old generation that
>> CMS has; background collection, foreground collection and full
>> compacting serial GC.
>> The functionality is only available in non-product builds.
>> With JDK-8064702 the foreground collector is being removed. This
>> means that there are only two types left. The
>> RotateCMSCollectionTypes flag is not being automatically tested and
>> it is very rarely used. Rather than maintaining it we should remove
>> this functionality. If we need this for debugging in the future it is
>> a pretty simple patch to add back. But for the most part it should be
>> possible to debug in other ways, by for example using
>> ExplicitGCInvokesConcurrent flag and similar.
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