RFR: 8342818: Implement CPU Time Profiling for JFR

[Johannes Bechberger]

On Tue, 10 Sep 2024 12:35:21 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

>> Just to clarify - you mean that when we do `JfrTraceIdLoadBarrier::get_sampler_enqueue_buffer(this)` in `jfrCPUTimeThreadSampler.cpp` it may not return `nullptr`?
>> Or the whole part of the new code using the `enqueue_buffer` is not needed?
>
> The whole part of calling this special, preemptive handling of an enqueue buffer is only because the JfrSamplerThread will suspend another thread (whiich might hold the malloc lock). Since this approach does not suspend threads, it can be removed. This thread will never tag while it has another thread suspended.

I removed all the checking of the buffer.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20752#discussion_r1756567025