!4627 add save checkpoint check durning parallel

Merge pull request !4627 from changzherui/add_ckpt_check

mindspore/train/serialization.py

@@ -396,15 +396,17 @@ def _get_merged_param_data(net, param_name, param_data):
     Returns:
         Tensor, the combined tensor which with the whole data value.
     """
-    layout = []
     layout = net.parameter_layout_dict[param_name]
-    if len(layout) < 2:
+    if len(layout) < 5:
         logger.info("layout dict does not contain the key %s", param_name)
         return param_data
 
     dev_mat = layout[0]
     tensor_map = layout[1]
     field_size = layout[3]
+    uniform_split = layout[4]
+    if uniform_split[0] == 0:
+        raise RuntimeError("Save checkpoint only support uniform split tensor now.")
 
     from mindspore.parallel._cell_wrapper import get_allgather_cell
     from mindspore.parallel._tensor import _reshape_param_data, _reshape_param_data_with_weight