[SPARK-3554] [PySpark] use broadcast automatically for large closure

Py4j can not handle large string efficiently, so we should use broadcast for large closure automatically. (Broadcast use local filesystem to pass through data).

Author: Davies Liu <davies.liu@gmail.com>

Closes #2417 from davies/command and squashes the following commits:

fbf4e97 [Davies Liu] bugfix
aefd508 [Davies Liu] use broadcast automatically for large closure

1 files changed, 6 insertions, 0 deletions

diff --git a/python/pyspark/tests.py b/python/pyspark/tests.py
index 0b3854347a..7301966e48 100644
--- a/python/pyspark/tests.py
+++ b/python/pyspark/tests.py
@@ -434,6 +434,12 @@ class TestRDDFunctions(PySparkTestCase):
         m = self.sc.parallelize(range(1), 1).map(lambda x: len(bdata.value)).sum()
         self.assertEquals(N, m)
 
+    def test_large_closure(self):
+        N = 1000000
+        data = [float(i) for i in xrange(N)]
+        m = self.sc.parallelize(range(1), 1).map(lambda x: len(data)).sum()
+        self.assertEquals(N, m)
+
     def test_zip_with_different_serializers(self):
         a = self.sc.parallelize(range(5))
         b = self.sc.parallelize(range(100, 105))