change: lazy import of tensorflow module (#1062)

Author: mvsusp

src/sagemaker/tensorflow/predictor.py

@@ -18,20 +18,31 @@
 import google.protobuf.json_format as json_format
 from google.protobuf.message import DecodeError
 from protobuf_to_dict import protobuf_to_dict
-from tensorflow.core.framework import tensor_pb2  # pylint: disable=no-name-in-module
-from tensorflow.python.framework import tensor_util  # pylint: disable=no-name-in-module
 
 from sagemaker.content_types import CONTENT_TYPE_JSON, CONTENT_TYPE_OCTET_STREAM, CONTENT_TYPE_CSV
 from sagemaker.predictor import json_serializer, csv_serializer
-from tensorflow_serving.apis import predict_pb2, classification_pb2, inference_pb2, regression_pb2
 
-_POSSIBLE_RESPONSES = [
-    predict_pb2.PredictResponse,
-    classification_pb2.ClassificationResponse,
-    inference_pb2.MultiInferenceResponse,
-    regression_pb2.RegressionResponse,
-    tensor_pb2.TensorProto,
-]
+
+def _possible_responses():
+    """
+    Returns: Possible available request types.
+    """
+    from tensorflow.core.framework import tensor_pb2  # pylint: disable=no-name-in-module
+    from tensorflow_serving.apis import (
+        predict_pb2,
+        classification_pb2,
+        inference_pb2,
+        regression_pb2,
+    )
+
+    return [
+        predict_pb2.PredictResponse,
+        classification_pb2.ClassificationResponse,
+        inference_pb2.MultiInferenceResponse,
+        regression_pb2.RegressionResponse,
+        tensor_pb2.TensorProto,
+    ]
+
 
 REGRESSION_REQUEST = "RegressionRequest"
 MULTI_INFERENCE_REQUEST = "MultiInferenceRequest"
@@ -88,7 +99,7 @@ def __call__(self, stream, content_type):
         finally:
             stream.close()
 
-        for possible_response in _POSSIBLE_RESPONSES:
+        for possible_response in _possible_responses():
             try:
                 response = possible_response()
                 response.ParseFromString(data)
@@ -114,6 +125,9 @@ def __call__(self, data):
         Args:
             data:
         """
+
+        from tensorflow.core.framework import tensor_pb2  # pylint: disable=no-name-in-module
+
         if isinstance(data, tensor_pb2.TensorProto):
             return json_format.MessageToJson(data)
         return json_serializer(data)
@@ -139,7 +153,7 @@ def __call__(self, stream, content_type):
         finally:
             stream.close()
 
-        for possible_response in _POSSIBLE_RESPONSES:
+        for possible_response in _possible_responses():
             try:
                 return protobuf_to_dict(json_format.Parse(data, possible_response()))
             except (UnicodeDecodeError, DecodeError, json_format.ParseError):
@@ -164,6 +178,10 @@ def __call__(self, data):
             data:
         """
         to_serialize = data
+
+        from tensorflow.core.framework import tensor_pb2  # pylint: disable=no-name-in-module
+        from tensorflow.python.framework import tensor_util  # pylint: disable=no-name-in-module
+
         if isinstance(data, tensor_pb2.TensorProto):
             to_serialize = tensor_util.MakeNdarray(data)
         return csv_serializer(to_serialize)