RFR: 8291753: Add JFR event for GC CPU Time

[Sangheon Kim]

On 8/11/22 12:34 PM, Erik Gahlin wrote:
> On Thu, 4 Aug 2022 23:58:02 GMT, Sangheon Kim <sangheki at openjdk.org> wrote:
>
>> Hi all,
>>
>> Could I have reviews to add new JFR event for GC CPU time?
>> Currently only log message is available for CPU time (user, system, real).
>> As there is already GCTraceCPUTime class which is used for a log message, I added GCTracer to deliver the event.
>> The log message of CPU time is printed after GC is completed and tried to keep same.
>>
>> For G1, manually checked there is not difference.
>>
>> For test, I had to add an exception as GCCpuTime will be generated after GC end.
>>
>> Testing: tier 1 ~ 3
>>
>> Thanks,
>> Sangheon
> Does this event doesn't provide CPU usage for ZGC and Shenandoah?
No.
This event is provided via GCTraceCPUTime class with GCTracer. And both 
ZGC and Shenanadoah are not using it.
If you are suggesting to support all GCs, it is out of scope. It may be 
address as a separate enhancement.

Thanks,
Sangheon


>
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>
> PR: https://git.openjdk.org/jdk/pull/9760