RFR: 8197425: Liveset information for Old Object sample event

[Erik Helin]

Hi Erik,

On 06/27/2018 09:49 AM, Erik Gahlin wrote:
> Here is an updated webrev.
> 
> http://cr.openjdk.java.net/~egahlin/8197425_2

I can't comment on the LeakProfiler and/or JFR parts of the patch 
(essentially the whole patch), but I can say that the patch now uses a 
much better API from the GC's point of view :)

So the usage of Universe::get_heap_used_at_last_gc() seems correct, 
unfortunately I lack the knowledge to review the rest of the patch :(

Thanks,
Erik

> 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
>