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

[Serguei Spitsyn]

On Wed, 7 Jun 2023 21:12:24 GMT, Alex Menkov <amenkov at openjdk.org> wrote:

>> Serguei Spitsyn has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   fix trailing space in jvmtiEnvBase.cpp
>
> src/hotspot/share/prims/jvmtiEnvBase.cpp line 765:
> 
>> 763:   if (is_thread_carrying_vthread(jt, thread_oop)) {
>> 764:     state &= ~JVMTI_THREAD_STATE_RUNNABLE;
>> 765:     state |= JVMTI_THREAD_STATE_WAITING | JVMTI_THREAD_STATE_WAITING_INDEFINITELY;
> 
> This does not look correct.
> GetThreadState spec provides hierarchical set of questions to interpret thread state value.
> JVMTI_THREAD_STATE_ALIVE | JVMTI_THREAD_STATE_WAITING | JVMTI_THREAD_STATE_WAITING_INDEFINITELY is only one branch and I'd expect all other bits are not set for this state.
> Need to decide what do we want to report as carrier thread state for all possible values returned by get_thread_state_base().

Good concern.
There are two bits (and the related RUNNABLE bit) that we care in this sub-tree of state bits: `SUSPENDED` and `INTERRUPTED`. This update clones these two bits. The RUNNABLE bit must be cleared.
A thread carrying a virtual thread can not be in native, blocked, parked, sleeping or waiting on some object.
The state returned by the `get_thread_state_base` is based on the call:
`    state = (jint)java_lang_Thread::get_thread_status(thread_oop);`
and addition of the derived from JavaThread bits: `SUSPENDED`, `INTERRUPTED` and `IN_NATIVE`.
The three bit derived from the JavaThread are not relevant.
This call has to be made directly:
`   state = (jint)java_lang_Thread::get_thread_status(thread_oop);`
The SUSPEND bit has to be based on the call:
`    jt->is_carrier_thread_suspended();`

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PR Review Comment: https://git.openjdk.org/jdk/pull/14366#discussion_r1222212064