Repository: spark
Updated Branches:
refs/heads/master 150d26cad -> 95c95b71e
[SPARK-18281] [SQL] [PYSPARK] Remove timeout for reading data through socket
for local iterator
## What changes were proposed in this pull request?
There is a timeout failure when using `rdd.toLocalIterator()` or
`df.toLocalIterator()` for a PySpark RDD and DataFrame:
df = spark.createDataFrame([[1],[2],[3]])
it = df.toLocalIterator()
row = next(it)
df2 = df.repartition(1000) # create many empty partitions which increase
materialization time so causing timeout
it2 = df2.toLocalIterator()
row = next(it2)
The cause of this issue is, we open a socket to serve the data from JVM side.
We set timeout for connection and reading through the socket in Python side. In
Python we use a generator to read the data, so we only begin to connect the
socket once we start to ask data from it. If we don't consume it immediately,
there is connection timeout.
In the other side, the materialization time for RDD partitions is
unpredictable. So we can't set a timeout for reading data through the socket.
Otherwise, it is very possibly to fail.
## How was this patch tested?
Added tests into PySpark.
Please review http://spark.apache.org/contributing.html before opening a pull
request.
Author: Liang-Chi Hsieh <vii...@gmail.com>
Closes #16263 from viirya/fix-pyspark-localiterator.
Project: http://git-wip-us.apache.org/repos/asf/spark/repo
Commit: http://git-wip-us.apache.org/repos/asf/spark/commit/95c95b71
Tree: http://git-wip-us.apache.org/repos/asf/spark/tree/95c95b71
Diff: http://git-wip-us.apache.org/repos/asf/spark/diff/95c95b71
Branch: refs/heads/master
Commit: 95c95b71ed31b2971475aec6d7776dc234845d0a
Parents: 150d26c
Author: Liang-Chi Hsieh <vii...@gmail.com>
Authored: Tue Dec 20 13:12:16 2016 -0800
Committer: Davies Liu <davies....@gmail.com>
Committed: Tue Dec 20 13:12:16 2016 -0800
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python/pyspark/rdd.py | 11 +++++------
python/pyspark/tests.py | 12 ++++++++++++
2 files changed, 17 insertions(+), 6 deletions(-)
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http://git-wip-us.apache.org/repos/asf/spark/blob/95c95b71/python/pyspark/rdd.py
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diff --git a/python/pyspark/rdd.py b/python/pyspark/rdd.py
index 9e05da8..b384b2b 100644
--- a/python/pyspark/rdd.py
+++ b/python/pyspark/rdd.py
@@ -135,12 +135,11 @@ def _load_from_socket(port, serializer):
break
if not sock:
raise Exception("could not open socket")
- try:
- rf = sock.makefile("rb", 65536)
- for item in serializer.load_stream(rf):
- yield item
- finally:
- sock.close()
+ # The RDD materialization time is unpredicable, if we set a timeout for
socket reading
+ # operation, it will very possibly fail. See SPARK-18281.
+ sock.settimeout(None)
+ # The socket will be automatically closed when garbage-collected.
+ return serializer.load_stream(sock.makefile("rb", 65536))
def ignore_unicode_prefix(f):
http://git-wip-us.apache.org/repos/asf/spark/blob/95c95b71/python/pyspark/tests.py
----------------------------------------------------------------------
diff --git a/python/pyspark/tests.py b/python/pyspark/tests.py
index 89fce8a..fe314c5 100644
--- a/python/pyspark/tests.py
+++ b/python/pyspark/tests.py
@@ -502,6 +502,18 @@ class RDDTests(ReusedPySparkTestCase):
self.assertEqual(0, self.sc.emptyRDD().sum())
self.assertEqual(6, self.sc.parallelize([1, 2, 3]).sum())
+ def test_to_localiterator(self):
+ from time import sleep
+ rdd = self.sc.parallelize([1, 2, 3])
+ it = rdd.toLocalIterator()
+ sleep(5)
+ self.assertEqual([1, 2, 3], sorted(it))
+
+ rdd2 = rdd.repartition(1000)
+ it2 = rdd2.toLocalIterator()
+ sleep(5)
+ self.assertEqual([1, 2, 3], sorted(it2))
+
def test_save_as_textfile_with_unicode(self):
# Regression test for SPARK-970
x = u"\u00A1Hola, mundo!"
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