[SPARK-2079] Support batching when serializing SchemaRDD to Python

Added batching with default batch size 10 in SchemaRDD.javaToPython

Author: Kan Zhang <kzhang@apache.org>

Closes #1023 from kanzhang/SPARK-2079 and squashes the following commits:

2d1915e [Kan Zhang] [SPARK-2079] Add batching in SchemaRDD.javaToPython
19b0c09 [Kan Zhang] [SPARK-2079] Removing unnecessary wrapping in SchemaRDD.javaToPython

1 files changed, 3 insertions, 1 deletions

diff --git a/python/pyspark/sql.py b/python/pyspark/sql.py
index 960d0a8244..e344610b1f 100644
--- a/python/pyspark/sql.py
+++ b/python/pyspark/sql.py
@@ -16,6 +16,7 @@
 #
 
 from pyspark.rdd import RDD
+from pyspark.serializers import BatchedSerializer, PickleSerializer
 
 from py4j.protocol import Py4JError
 
@@ -346,7 +347,8 @@ class SchemaRDD(RDD):
         # TODO: This is inefficient, we should construct the Python Row object
         # in Java land in the javaToPython function. May require a custom
         # pickle serializer in Pyrolite
-        return RDD(jrdd, self._sc, self._sc.serializer).map(lambda d: Row(d))
+        return RDD(jrdd, self._sc, BatchedSerializer(
+                        PickleSerializer())).map(lambda d: Row(d))
 
     # We override the default cache/persist/checkpoint behavior as we want to cache the underlying
     # SchemaRDD object in the JVM, not the PythonRDD checkpointed by the super class