ASSERT_TRUE(worker_server1->Start().ok());

  // 5a. Update `ctx_0` with updated `server_def_0`.
  {
    server_def_0.set_task_index(0);
    string serialized_update = server_def_0.SerializeAsString();
    TF_Status* status = TF_NewStatus();
    TFE_ContextUpdateServerDefWithTimeout(ctx_0, 0, serialized_update.data(),
                                          serialized_update.size(),