RFR: 8309612: [REDO] JDK-8307153 JVMTI GetThreadState on carrier should return STATE_WAITING [v4]

[Serguei Spitsyn]

On Wed, 7 Jun 2023 22:48:47 GMT, Alex Menkov <amenkov at openjdk.org> wrote:

>> Do you need to check jt->is_interrupted(false) and set INTERRUPTED bit?
>> It looks like java_lang_Thread::get_thread_status(thread_oop) can only return RUNNABLE in the case and we clear it, so the call is not needed:
>> 
>>     if (is_thread_carrying_vthread(jt, thread_oop)) {
>>       jint state = JVMTI_THREAD_STATE_WAITING | JVMTI_THREAD_STATE_WAITING_INDEFINITELY;
>>       if (jt->is_carrier_thread_suspended()) {
>>         state |= JVMTI_THREAD_STATE_SUSPENDED;
>>       }
>>       if (jt->is_interrupted(false)) {
>>         state |= JVMTI_THREAD_STATE_INTERRUPTED;
>>       }
>>       return state;
>>     } else ...
>
>> A thread carrying a virtual thread can not be in native, blocked, parked, sleeping or waiting on some object.
> 
> Actually it can be in native.
> And if I remember correctly synchronized block pins virtual thread, so inside synchronized we can get other states

The INTERRUPTED bit we need has to be returned by the `java_lang_Thread::get_thread_status`.
Not completely sure but the bit jt->is_interrupted(false) can be set for the mounted virtual thread.
The JVMTI InterruptThread calls this function to set interrupt bit for non-virtual threads:
`  java_lang_Thread::set_interrupted(thread_obj, true);`

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PR Review Comment: https://git.openjdk.org/jdk/pull/14366#discussion_r1222268031