message: hot fix - missing dense layer AllReduce while multiple node training and each node has one GPU
diff: @@ -159,7 +159,7 @@ Error_t Session::train() {
  assert(!"networks_.size() should not less than 1.");
  }
  // wgrad exchange
  - if (networks_.size() > 1) {
  + if (gpu_resource_group_.get_total_gpu_count() > 1) {
  CK_NCCL_THROW_(ncclGroupStart());
  for (auto network : networks_) {
  network->exchange_wgrad();
  