RFR: 8342818: Implement CPU Time Profiling for JFR [v4]

[Johannes Bechberger]

On Thu, 31 Oct 2024 22:48:38 GMT, Dean Long <dlong at openjdk.org> wrote:

>> Johannes Bechberger has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Remove min_valid_free_size_bytes
>
> src/hotspot/share/jfr/periodic/sampling/jfrCPUTimeThreadSampler.cpp line 221:
> 
>> 219:       _error = ERROR_NO_TOPFRAME;
>> 220:       return;
>> 221:     }
> 
> Wouldn't we end up with the same top frame if we started at the anchor frame instead?  In fact, the frame we want should always be the immediate caller of the anchor frame.  But I guess we need to check that the anchor frame is walkable.

This is not always the case, as far as I know.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20752#discussion_r1825280641