docs: public void printStack(long tid) throws IOException {
  		System.out.printf("%n Stack trace of thread %d:%n", tid);
  
  		ThreadInfo info = view.vmInfo.getThreadInfo(tid, 20);
  		if (info == null) {
  			System.err.println(" TID not exist:" + tid);
  			return;
  		}
  		printSingleThread(info);
  		System.out.flush();
  	}