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

[Severin Gehwolf]

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

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?

Thanks,
Severin