RFR: 8328083: degrade virtual thread support for GetObjectMonitorUsage [v4]

[Serguei Spitsyn]

On Wed, 15 May 2024 19:52:36 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

>> Serguei Spitsyn has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   review: 1. clarifications in JDWP and JDI spec; 2. clarifications in test comments.
>
> src/hotspot/share/prims/jvmtiEnvBase.cpp line 1583:
> 
>> 1581:         assert(w != nullptr, "sanity check");
>> 1582:         if (java_lang_VirtualThread::is_instance(thread_oop)) {
>> 1583:           skipped++;
> 
> I don't think maintaining `skipped` does anything here.

Thank you for the question. It is needed at the line 1586 below to discount the index:

        if (java_lang_VirtualThread::is_instance(thread_oop)) {
          skipped++;
        } else {
          // If the thread was found on the ObjectWaiter list, then
          // it has not been notified.
          Handle th(current_thread, get_vthread_or_thread_oop(w));
1586:     ret.notify_waiters[i - skipped] = (jthread)jni_reference(calling_thread, th);
        }

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PR Review Comment: https://git.openjdk.org/jdk/pull/19030#discussion_r1602193077