RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v58]

[Johannes Bechberger]

On Wed, 4 Jun 2025 19:15:19 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

>> src/hotspot/share/jfr/periodic/sampling/jfrCPUTimeThreadSampler.cpp line 656:
>> 
>>> 654:   if ((prev_handler != SIG_DFL && prev_handler != SIG_IGN && prev_handler != (void*)::handle_timer_signal) ||
>>> 655:       PosixSignals::install_generic_signal_handler(SIG, (void*)::handle_timer_signal) == (void*)-1) {
>>> 656:     log_error(jfr)("CPUTimeSample events will not be recorded: %p", prev_handler);
>> 
>> A message with some random hex address may look cryptic.
>> Maybe make it a bit more user-friendly? E.g.
>> 
>> Conflicting SIGPROF handler found: %p. CPUTimeSample events will not be recorded
>
> Thanks Andrei.

Fixed it.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2127292777