--- a/hotspot/src/share/vm/runtime/thread.hpp	Mon Mar 02 13:57:17 2009 -0700
+++ b/hotspot/src/share/vm/runtime/thread.hpp	Mon Mar 02 14:00:23 2009 -0700
@@ -1345,6 +1345,13 @@
  public:
   // Thread local information maintained by JVMTI.
   void set_jvmti_thread_state(JvmtiThreadState *value)                           { _jvmti_thread_state = value; }
+  // A JvmtiThreadState is lazily allocated. This jvmti_thread_state()
+  // getter is used to get this JavaThread's JvmtiThreadState if it has
+  // one which means NULL can be returned. JvmtiThreadState::state_for()
+  // is used to get the specified JavaThread's JvmtiThreadState if it has
+  // one or it allocates a new JvmtiThreadState for the JavaThread and
+  // returns it. JvmtiThreadState::state_for() will return NULL only if
+  // the specified JavaThread is exiting.
   JvmtiThreadState *jvmti_thread_state() const                                   { return _jvmti_thread_state; }
   static ByteSize jvmti_thread_state_offset()                                    { return byte_offset_of(JavaThread, _jvmti_thread_state); }
   void set_jvmti_get_loaded_classes_closure(JvmtiGetLoadedClassesClosure* value) { _jvmti_get_loaded_classes_closure = value; }