[SPARK-5973] [PySpark] fix zip with two RDDs with AutoBatchedSerializer

Author: Davies Liu <[email protected]>

Closes #4745 from davies/fix_zip and squashes the following commits:

2124b2c [Davies Liu] Update tests.py
b5c828f [Davies Liu] increase the number of records
c1e40fd [Davies Liu] fix zip with two RDDs with AutoBatchedSerializer

Author: Davies Liu

python/pyspark/rdd.py

@@ -1950,7 +1950,7 @@ def batch_as(rdd, batchSize):
 
         my_batch = get_batch_size(self._jrdd_deserializer)
         other_batch = get_batch_size(other._jrdd_deserializer)
-        if my_batch != other_batch:
+        if my_batch != other_batch or not my_batch:
             # use the smallest batchSize for both of them
             batchSize = min(my_batch, other_batch)
             if batchSize <= 0:

python/pyspark/tests.py

@@ -543,6 +543,12 @@ def test_zip_with_different_serializers(self):
         # regression test for bug in _reserializer()
         self.assertEqual(cnt, t.zip(rdd).count())
 
+    def test_zip_with_different_object_sizes(self):
+        # regress test for SPARK-5973
+        a = self.sc.parallelize(range(10000)).map(lambda i: '*' * i)
+        b = self.sc.parallelize(range(10000, 20000)).map(lambda i: '*' * i)
+        self.assertEqual(10000, a.zip(b).count())
+
     def test_zip_with_different_number_of_items(self):
         a = self.sc.parallelize(range(5), 2)
         # different number of partitions