code: @Override
    protected void postGlobal() {
      assert(_res.model_info().get_params().replicate_training_data);
      super.postGlobal();
      _res.model_info().div(_res._chunk_node_count); //model averaging
      _res.model_info().add_processed_global(_res.model_info().get_processed_local()); //switch from local counters to global counters
      _res.model_info().set_processed_local(0l);
    }
docs: Finish up the work after all nodes have reduced their models via the above reduce() method.
  All we do is average the models and add to the global training sample counter.
  After this returns, model_info() can be queried for the updated model.