code: public static void start(String name) {
      if (!active) return;
  
      TimerNode root = new TimerNode(name, System.currentTimeMillis());
      TimerStack stack = (TimerStack) curStack.get();
      if (null == stack) curStack.set(new TimerStack(root));
      else stack.push(root);
    }
docs: Create and start a performance profiling with the <code>name</code> given. Deal with
  profile hierarchy automatically, so caller don't have to be concern about it.
  
  @param name profile name