RFR: 8342818: Implement CPU Time Profiling for JFR

[Johannes Bechberger]

On Tue, 10 Sep 2024 13:24:22 GMT, Erik Gahlin <egahlin at openjdk.org> wrote:

>> src/jdk.jfr/share/classes/jdk/jfr/internal/query/view.ini line 419:
>> 
>>> 417: 
>>> 418: [application.cpu-time-overflowed-samples]
>>> 419: label = "CPU Time Samples not recorded because of internal throttling"
>> 
>> Align rename for CPUTimeSampleLoss
>
> Why are events with stack trace = null emitted? Isn't CPUTimeExecutionSampleLoss sufficient?

This happens when the JVM is unable to walk a specific stack trace, but the queues are not full, and when the JVM is unable to resolve `Method` pointers.

The main idea behind it is that we still record that the thread runs on the CPU at this point in time; we just don't have any proper information on the stack trace. Only knowing that a thread run is still valuable information.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/20752#discussion_r1752025272