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

[Johannes Bechberger]

On Wed, 30 Oct 2024 21:11:53 GMT, Erik Gahlin <egahlin at openjdk.org> wrote:

>> The problem is, is that `eventType.hasStackTrace()` checks for the existence of a field called `stackTrace`, which CPUTimeSample events have. We could of course rename the field to something like `recordedStackTrace`, but I don't think that this is helpful.
>
> Shouldn't the event have a stackTrace setting and the setting be set to true in default.jfc, similar to ObjectAlllocationSample?
> 
> metadata.xml:
>   <Event name="ObjectAllocationSample" thread="true" stackTrace="true" startTime="false" throttle="true">
>     <Field type="Class" name="objectClass" label="Object Class" />
>     <Field type="long" contentType="bytes" name="weight"  />
>   </Event>
> 
> default.jfc:
>   <event name="jdk.ObjectAllocationSample">
>     <setting name="enabled">true</setting>
>     <setting name="throttle">150/s</setting>
>     <setting name="stackTrace">true</setting>
>   </event>

This would also be an option.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20752#discussion_r1823409449