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

src/hotspot/share/prims/jvmtiEnvBase.cpp

@@ -761,6 +761,10 @@ JvmtiEnvBase::get_thread_state(oop thread_oop, JavaThread* jt) {
   jint state = get_thread_state_base(thread_oop, jt);
 
   if (is_thread_carrying_vthread(jt, thread_oop)) {
+    // It's okay for the JVMTI state to be reported as WAITING when waiting
+    // for something other than an Object.wait. So, we treat a thread carrying
+    // a virtual thread as waiting indefinitely which is not runnable.
+    // It is why the RUNNABLE bit is cleared and the WAITING bits are added.
     state &= ~JVMTI_THREAD_STATE_RUNNABLE;
     state |= JVMTI_THREAD_STATE_WAITING | JVMTI_THREAD_STATE_WAITING_INDEFINITELY;
   }
@@ -1736,7 +1740,7 @@ JvmtiEnvBase::suspend_thread(oop thread_oop, JavaThread* java_thread, bool singl
           (is_virtual && JvmtiVTSuspender::is_vthread_suspended(thread_h())),
          "sanity check");
 
-  // An attempt to handshake-suspend a thread carrying virtual thread will result in
+  // An attempt to handshake-suspend a thread carrying a virtual thread will result in
   // suspension of mounted virtual thread. So, we just mark it as suspended
   // and it will be actually suspended at virtual thread unmount transition.
   if (!is_thread_carrying) {

src/hotspot/share/prims/jvmtiEnvBase.hpp

@@ -96,7 +96,7 @@ class JvmtiEnvBase : public CHeapObj<mtInternal> {
   static jvmtiError check_thread_list(jint count, const jthread* list);
   static bool is_in_thread_list(jint count, const jthread* list, oop jt_oop);
 
-  // check if thread_oop represents a thread carrying virtual thread
+  // check if thread_oop represents a thread carrying a virtual thread
   static bool is_thread_carrying_vthread(JavaThread* java_thread, oop thread_oop) {
     return java_thread != nullptr && java_thread->jvmti_vthread() != nullptr
                                && java_thread->jvmti_vthread() != thread_oop
@@ -180,7 +180,7 @@ class JvmtiEnvBase : public CHeapObj<mtInternal> {
   static oop current_thread_obj_or_resolve_external_guard(jthread thread);
 
   // Return true if the thread identified with a pair <jt,thr_obj> is current.
-  // A thread carrying virtual thread is not treated as current.
+  // A thread carrying a virtual thread is not treated as current.
   static bool is_JavaThread_current(JavaThread* jt, oop thr_obj) {
     JavaThread* current = JavaThread::current();
     // jt can be null in case of a virtual thread