RFR: 8197425: Liveset information for Old Object sample event

[Erik Gahlin]

Here is an updated webrev.

http://cr.openjdk.java.net/~egahlin/8197425_2

Erik

> Hi,
>
> Could I have a review of an enhancement that adds heap usage after GC 
> to the Old Object Sample (OOS) event. This is useful for spotting an 
> increasing liveset.
>
> Recordings typically only contain data for a limited period, i .e. 
> last 30 minutes, but the OOS event contains samples from when JFR/JVM 
> was started, potentially several days back.
>
> The liveset trend is useful for tools such as Mission Control to 
> detect if there is a memory leak. If that is the case, information in 
> the OOS event can be used to pinpoint where the leak occurred and what 
> is keeping it alive. Presenting this information when there is not 
> memory leak is confusing.
>
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8197425
>
> Webrev:
> http://cr.openjdk.java.net/~egahlin/8197425/
>
> Testings:
> Tests in test/jdk/jdk/jfr
>
> Thanks
> Erik