RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v5]

[Johannes Bechberger]

On Mon, 26 May 2025 10:25:28 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

>> I can't follow. This is testing whether the queue is more than two thirds full.
>
> I'm sorry, I read this wrong. In this case, it does not matter: (capacity * 2) / 3 == capacity * (2/3)

I ignored the small underflow, so `size() * 3 > capacity() * 2` is more accurate, but far less readable.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2107034280