https://netprogdong.github.io/posts/D%E6%9C%BA%E6%88%BF%E5%85%AC%E7%BD%91vip%E9%83%A8%E5%88%86%E4%B8%8D%E9%80%9A%E6%88%96%E4%B8%A2%E5%8C%85%E9%97%AE%E9%A2%98/ 交换机bug
