RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v38]
Markus Grönlund
mgronlun at openjdk.org
Tue Jun 3 13:00:06 UTC 2025
On Tue, 3 Jun 2025 12:39:47 GMT, Johannes Bechberger <jbechberger at openjdk.org> wrote:
>> This is the code for the [JEP 509: CPU Time based profiling for JFR](https://openjdk.org/jeps/509).
>>
>> Currently tested using [this test suite](https://github.com/parttimenerd/basic-profiler-tests). This runs profiles the [Renaissance](https://renaissance.dev/) benchmark with
>> - ... different heap sizes
>> - ... different GCs
>> - ... different samplers (the standard JFR and the new CPU Time Sampler and both)
>> - ... different JFR recording durations
>> - ... different chunk-sizes
>
> Johannes Bechberger has updated the pull request incrementally with one additional commit since the last revision:
>
> Restrict threads for which timers are created
src/hotspot/share/jfr/periodic/sampling/jfrThreadSampling.cpp line 479:
> 477:
> 478: // Entry point for a thread that has been sampled in native code and has a pending JFR CPU time request.
> 479: void JfrThreadSampling::process_cpu_time_request(JavaThread* jt, JfrThreadLocal* tl, Thread* current, bool lock) {
Can you move this up to be co-located with "drain_enqueued_cpu_time_requests"? Thanks.
src/hotspot/share/jfr/periodic/sampling/jfrThreadSampling.hpp line 40:
> 38: public:
> 39: static void process_sample_request(JavaThread* jt, bool has_cpu_time_sample_request);
> 40: static void process_cpu_time_request(JavaThread* jt, JfrThreadLocal* tl, Thread* current, bool lock);
Put this under private and add JfrCPUTimeThreadSampler as a friend (like above with JfrSamplerThread and "process_native_sample_requests"
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2123728400
PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2123726144
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