ThreadBlockInVM(JavaThread *thread)
  : ThreadStateTransition(thread) {

  {- -------------------------------------------
  (1) JavaFrameAnchor::make_walkable() を呼んで, スタックフレームを辿れるようにしておく.
      ---------------------------------------- -}

        // Once we are blocked vm expects stack to be walkable
        thread->frame_anchor()->make_walkable(thread);

  {- -------------------------------------------
  (1) ThreadStateTransition::trans_and_fence() を呼んで, JavaThreadState を _thread_blocked に変更する.
      ---------------------------------------- -}

        trans_and_fence(_thread_in_vm, _thread_blocked);
      }