jmx-dev RFR: 8368527: JMX: Add an MXBeans method to query GC CPU time

[Jonas Norlinder]

On Tue, 30 Sep 2025 09:19:28 GMT, Bernd <duke at openjdk.org> wrote:

>> Just want to ensure that I read this correct, please correct any mistake below:
>> 
>> * concurrent time = `CPU time`
>> * accumulate times = `wall-clock time`
>> 
>> Is your suggestion that we should clarify that the method may only account for `CPU time` and not `wall-clock time` during pauses?
>
> It’s mostly about making clear it’s Not a measurement for pause time (no matter if wall clock or per thread), dont know how to best Formulate it. I think it’s needed sind typically pause times have been associated with GRC thread Timings. Maybe something like „the accounted CPU time can be spent concurrently with application threads or during pauses“ or something Like that?

In the CSR discussion I proposed changing the method name to `getTotalGcCpuTime()` as @kevinjwalls raised concerns about conflating it with per generation CPU timings. Would the renaming to `getTotalGcCpuTime()` also solve your concern here?

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PR Review Comment: https://git.openjdk.org/jdk/pull/27537#discussion_r2390533951