[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, 2 deletions

diff --git a/python/pyspark/sql.py b/python/pyspark/sql.py
index 8f6dbab240..42a9920f10 100644
--- a/python/pyspark/sql.py
+++ b/python/pyspark/sql.py
@@ -27,7 +27,7 @@ import warnings
 from array import array
 from operator import itemgetter
 
-from pyspark.rdd import RDD, PipelinedRDD
+from pyspark.rdd import RDD
 from pyspark.serializers import BatchedSerializer, PickleSerializer, CloudPickleSerializer
 from pyspark.storagelevel import StorageLevel
 from pyspark.traceback_utils import SCCallSiteSync
@@ -975,7 +975,11 @@ class SQLContext(object):
         command = (func,
                    BatchedSerializer(PickleSerializer(), 1024),
                    BatchedSerializer(PickleSerializer(), 1024))
-        pickled_command = CloudPickleSerializer().dumps(command)
+        ser = CloudPickleSerializer()
+        pickled_command = ser.dumps(command)
+        if pickled_command > (1 << 20):  # 1M
+            broadcast = self._sc.broadcast(pickled_command)
+            pickled_command = ser.dumps(broadcast)
         broadcast_vars = ListConverter().convert(
             [x._jbroadcast for x in self._sc._pickled_broadcast_vars],
             self._sc._gateway._gateway_client)