!2766 get default value if num_parallel_workers is None

Merge pull request !2766 from yanghaitao/yht_serialize_num_parallel_worker

mindspore/dataset/engine/serializer_deserializer.py

@@ -22,7 +22,7 @@ import sys
 from mindspore import log as logger
 from . import datasets as de
 from ..transforms.vision.utils import Inter, Border
-
+from ..core.configuration import config
 
 def serialize(dataset, json_filepath=None):
     """
@@ -164,6 +164,8 @@ def traverse(node):
             node_repr[k] = v.to_json()
         elif k in set(['schema', 'dataset_files', 'dataset_dir', 'schema_file_path']):
             expand_path(node_repr, k, v)
+        elif k == "num_parallel_workers" and v is None:
+            node_repr[k] = config.get_num_parallel_workers()
         else:
             node_repr[k] = v
 

tests/ut/python/dataset/test_config.py

@@ -84,12 +84,11 @@ def test_pipeline():
     num_parallel_workers_original = ds.config.get_num_parallel_workers()
 
     data1 = ds.TFRecordDataset(DATA_DIR, SCHEMA_DIR, shuffle=False)
-    ds.config.set_num_parallel_workers(2)
     data1 = data1.map(input_columns=["image"], operations=[c_vision.Decode(True)])
     ds.serialize(data1, "testpipeline.json")
 
-    data2 = ds.TFRecordDataset(DATA_DIR, SCHEMA_DIR, shuffle=False)
-    ds.config.set_num_parallel_workers(4)
+    data2 = ds.TFRecordDataset(DATA_DIR, SCHEMA_DIR, num_parallel_workers=num_parallel_workers_original,
+                               shuffle=False)
     data2 = data2.map(input_columns=["image"], operations=[c_vision.Decode(True)])
     ds.serialize(data2, "testpipeline2.json")