RFR 8221507: Implement JFR Events for Shenandoah

[Ken Dobson]

On Tue, Mar 26, 2019 at 5:16 PM Roman Kennke <rkennke at redhat.com> wrote:

> > Please review this patch that adds support for two new JFR events
> > ShenandoahHeapRegionStateChange and ShenandoahHeapRegionInformation.
> >
> > Bug: https://bugs.openjdk.java.net/browse/JDK-8221507
> > Webrev: http://cr.openjdk.java.net/~kdobson/53476/webrev/
> >
> > The events appears to result in ~2% overhead though there is some
> > uncertainty as to whether some of that is noise.
> >
> > Thanks,
> >
> > Ken Dobson
>
> Very nice!
>
> The overhead is only present with JFR active, I assume?
>
> We've noticed that there is some overhead when JFR is included in the jdk
but not running. This may be because the event object has to be
instantiated at each transition whether it's enabled or not. You can see
the exact numbers in the email I previously sent you.

Have you run hotspot_gc_shenandoah tests?
>
> Yes and all of the tests pass.

Thanks,

Ken Dobson