记一次死锁

  void UpdateIPAddrs() {
    proto::ServerReq req;
    proto::ServerRes res;
    while (!stop_) {
      grpc::ClientContext context;
      FillReq(&req);
      if (!DoRpc(req, &res)) {
        LOG(ERROR) << "Grpc error";
      } else {
        LOG(INFO) << "UpdateIPAddrs success";
      }
      std::unique_lock<std::mutex> locker(mu_);
      cv_.wait_for(locker, std::chrono::seconds(5), [this] { return stop_; });
    }

    thread_exists_ = true;
    LOG(INFO) << "UpdateIPAddrs exist";
  }

  void Shutdown() {
    stop_ = true;
    cv_.notify_all();
  }

  void Start() {
    auto task = std::bind(&GrpcClient::UpdateIPAddrs, this);
    util::ThreadPool::Instance()->Post(task);
  }

  void Await() {
    {
      std::unique_lock<std::mutex> locker(mu_);
      cv_.wait(locker, [this] { return stop_; });
    }
    while (!thread_exists_) {
      cv_.notify_all();
      util::Util::Sleep(200);
    }
  }