RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v50]

[Johannes Bechberger]

On Wed, 4 Jun 2025 14:56:10 GMT, Johannes Bechberger <jbechberger at openjdk.org> wrote:

>> The `sigev_value` member is used to pass data that you can read in the signal handler. The address of `t` won't be valid anymore once you return from this function. In that example the address of `timerid ` is still valid.
>
> Why is this a problem? We don't leak `&t` outside of `create_timer_for_thread`.

But I can start using the passed-in parameter `timerid` directly, which should make the code less confusing.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2126829360