RFR: 8292266: Add JFR event for total Reference processing time [v4]

[Albert Mingkun Yang]

On Fri, 18 Nov 2022 23:12:13 GMT, Sangheon Kim <sangheki at openjdk.org> wrote:

>> Hi all,
>> 
>> Can I have reviews for this change that adds a new JFR event for total Reference Processing time?
>> 
>> The goal is to generate a new JFR event if there is already measured time. This CR doesn't add new time measurement.
>> 
>> Testing: hs-tier1 ~ 3
>> 
>> Thanks,
>> Sangheon
>
> Sangheon Kim has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Thomas review

> Or if the confusion only comes from zero value of the measured time

Yes, that's the confusion I was referring to.

> My first commit is something like this but stopped as someone may complain lack of the event anyway.

I see; I actually like the approach in your first commit better -- separate methods for reporting ref counts and processing time. If an event is not supported for a particular collector, it should not be emitted for that collector, IMO.

I still feel the behavior, reporting zero for ref-processing time for Shenandoah and Z, can be surprising, so I'd prefer this is avoided. However, if others think this is fine, I would not block this.

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Marked as reviewed by ayang (Reviewer).

PR: https://git.openjdk.org/jdk/pull/11230