RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v26]

[Markus Grönlund]

On Mon, 2 Jun 2025 08:58:28 GMT, Johannes Bechberger <jbechberger at openjdk.org> wrote:

>> How so?
>
> Because we need to add the threads from the signal handler. So any kind of growing array or set would not work, especially if we want to remove the threads from within the signal handler again.
> 
> This is certainly an area of future optimization, albeit this doesn't seem to have any measurable performance impact in my renaissance benchmark runs.

I don't understand what allocation has to do with anything. I'm talking about code branch layout to avoid having to test "has_cpu_time_jfr_requests()" when we know it will be false by default.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2120846868