[SPARK-12091] [PYSPARK] Deprecate the JAVA-specific deserialized storage levels

docs/configuration.md

@@ -678,9 +678,10 @@ Apart from these, the following properties are also available, and may be useful
   <td><code>spark.rdd.compress</code></td>
   <td>false</td>
   <td>
-    Whether to compress serialized RDD partitions (e.g. for
-    <code>StorageLevel.MEMORY_ONLY_SER</code>). Can save substantial space at the cost of some
-    extra CPU time.
+    Whether to compress serialized RDD partitions (e.g. for 
+    <code>StorageLevel.MEMORY_ONLY_SER</code> in Java 
+    and Scala or <code>StorageLevel.MEMORY_ONLY</code> in Python). 
+    Can save substantial space at the cost of some extra CPU time. 
   </td>
 </tr>
 <tr>

docs/programming-guide.md

@@ -1196,14 +1196,14 @@ storage levels is:
     partitions that don't fit on disk, and read them from there when they're needed. </td>
 </tr>
 <tr>
-  <td> MEMORY_ONLY_SER </td>
+  <td> MEMORY_ONLY_SER <br /> (Java and Scala) </td>
   <td> Store RDD as <i>serialized</i> Java objects (one byte array per partition).
     This is generally more space-efficient than deserialized objects, especially when using a
     <a href="tuning.html">fast serializer</a>, but more CPU-intensive to read.
   </td>
 </tr>
 <tr>
-  <td> MEMORY_AND_DISK_SER </td>
+  <td> MEMORY_AND_DISK_SER <br /> (Java and Scala) </td>
   <td> Similar to MEMORY_ONLY_SER, but spill partitions that don't fit in memory to disk instead of
     recomputing them on the fly each time they're needed. </td>
 </tr>
@@ -1230,7 +1230,9 @@ storage levels is:
 </tr>
 </table>
 
-**Note:** *In Python, stored objects will always be serialized with the [Pickle](https://docs.python.org/2/library/pickle.html) library, so it does not matter whether you choose a serialized level.*
+**Note:** *In Python, stored objects will always be serialized with the [Pickle](https://docs.python.org/2/library/pickle.html) library, 
+so it does not matter whether you choose a serialized level. The available storage levels in Python include `MEMORY_ONLY`, `MEMORY_ONLY_2`, 
+`MEMORY_AND_DISK`, `MEMORY_AND_DISK_2`, `DISK_ONLY`, `DISK_ONLY_2` and `OFF_HEAP`.*
 
 Spark also automatically persists some intermediate data in shuffle operations (e.g. `reduceByKey`), even without users calling `persist`. This is done to avoid recomputing the entire input if a node fails during the shuffle. We still recommend users call `persist` on the resulting RDD if they plan to reuse it.
 
@@ -1243,7 +1245,7 @@ efficiency. We recommend going through the following process to select one:
   This is the most CPU-efficient option, allowing operations on the RDDs to run as fast as possible.
 
 * If not, try using `MEMORY_ONLY_SER` and [selecting a fast serialization library](tuning.html) to
-make the objects much more space-efficient, but still reasonably fast to access.
+make the objects much more space-efficient, but still reasonably fast to access. (Java and Scala)
 
 * Don't spill to disk unless the functions that computed your datasets are expensive, or they filter
 a large amount of the data. Otherwise, recomputing a partition may be as fast as reading it from

python/pyspark/rdd.py

@@ -220,18 +220,18 @@ def context(self):
 
     def cache(self):
         """
-        Persist this RDD with the default storage level (C{MEMORY_ONLY_SER}).
+        Persist this RDD with the default storage level (C{MEMORY_ONLY}).
         """
         self.is_cached = True
-        self.persist(StorageLevel.MEMORY_ONLY_SER)
+        self.persist(StorageLevel.MEMORY_ONLY)
         return self
 
-    def persist(self, storageLevel=StorageLevel.MEMORY_ONLY_SER):
+    def persist(self, storageLevel=StorageLevel.MEMORY_ONLY):
         """
         Set this RDD's storage level to persist its values across operations
         after the first time it is computed. This can only be used to assign
         a new storage level if the RDD does not have a storage level set yet.
-        If no storage level is specified defaults to (C{MEMORY_ONLY_SER}).
+        If no storage level is specified defaults to (C{MEMORY_ONLY}).
 
         >>> rdd = sc.parallelize(["b", "a", "c"])
         >>> rdd.persist().is_cached

python/pyspark/sql/dataframe.py

@@ -371,18 +371,18 @@ def foreachPartition(self, f):
 
     @since(1.3)
     def cache(self):
-        """ Persists with the default storage level (C{MEMORY_ONLY_SER}).
+        """ Persists with the default storage level (C{MEMORY_ONLY}).
         """
         self.is_cached = True
         self._jdf.cache()
         return self
 
     @since(1.3)
-    def persist(self, storageLevel=StorageLevel.MEMORY_ONLY_SER):
+    def persist(self, storageLevel=StorageLevel.MEMORY_ONLY):
         """Sets the storage level to persist its values across operations
         after the first time it is computed. This can only be used to assign
         a new storage level if the RDD does not have a storage level set yet.
-        If no storage level is specified defaults to (C{MEMORY_ONLY_SER}).
+        If no storage level is specified defaults to (C{MEMORY_ONLY}).
         """
         self.is_cached = True
         javaStorageLevel = self._sc._getJavaStorageLevel(storageLevel)

python/pyspark/storagelevel.py

@@ -23,8 +23,10 @@ class StorageLevel(object):
     """
     Flags for controlling the storage of an RDD. Each StorageLevel records whether to use memory,
     whether to drop the RDD to disk if it falls out of memory, whether to keep the data in memory
-    in a serialized format, and whether to replicate the RDD partitions on multiple nodes.
-    Also contains static constants for some commonly used storage levels, such as MEMORY_ONLY.
+    in a JAVA-specific serialized format, and whether to replicate the RDD partitions on multiple
+    nodes. Also contains static constants for some commonly used storage levels, MEMORY_ONLY.
+    Since the data is always serialized on the Python side, all the constants use the serialized
+    formats.
     """
 
     def __init__(self, useDisk, useMemory, useOffHeap, deserialized, replication=1):
@@ -49,12 +51,21 @@ def __str__(self):
 
 StorageLevel.DISK_ONLY = StorageLevel(True, False, False, False)
 StorageLevel.DISK_ONLY_2 = StorageLevel(True, False, False, False, 2)
-StorageLevel.MEMORY_ONLY = StorageLevel(False, True, False, True)
-StorageLevel.MEMORY_ONLY_2 = StorageLevel(False, True, False, True, 2)
-StorageLevel.MEMORY_ONLY_SER = StorageLevel(False, True, False, False)
-StorageLevel.MEMORY_ONLY_SER_2 = StorageLevel(False, True, False, False, 2)
-StorageLevel.MEMORY_AND_DISK = StorageLevel(True, True, False, True)
-StorageLevel.MEMORY_AND_DISK_2 = StorageLevel(True, True, False, True, 2)
-StorageLevel.MEMORY_AND_DISK_SER = StorageLevel(True, True, False, False)
-StorageLevel.MEMORY_AND_DISK_SER_2 = StorageLevel(True, True, False, False, 2)
+StorageLevel.MEMORY_ONLY = StorageLevel(False, True, False, False)
+StorageLevel.MEMORY_ONLY_2 = StorageLevel(False, True, False, False, 2)
+StorageLevel.MEMORY_AND_DISK = StorageLevel(True, True, False, False)
+StorageLevel.MEMORY_AND_DISK_2 = StorageLevel(True, True, False, False, 2)
 StorageLevel.OFF_HEAP = StorageLevel(False, False, True, False, 1)
+
+"""
+.. note:: The following four storage level constants are deprecated in 2.0, since the records \
+will always be serialized in Python.
+"""
+StorageLevel.MEMORY_ONLY_SER = StorageLevel.MEMORY_ONLY
+""".. note:: Deprecated in 2.0, use ``StorageLevel.MEMORY_ONLY`` instead."""
+StorageLevel.MEMORY_ONLY_SER_2 = StorageLevel.MEMORY_ONLY_2
+""".. note:: Deprecated in 2.0, use ``StorageLevel.MEMORY_ONLY_2`` instead."""
+StorageLevel.MEMORY_AND_DISK_SER = StorageLevel.MEMORY_AND_DISK
+""".. note:: Deprecated in 2.0, use ``StorageLevel.MEMORY_AND_DISK`` instead."""
+StorageLevel.MEMORY_AND_DISK_SER_2 = StorageLevel.MEMORY_AND_DISK_2
+""".. note:: Deprecated in 2.0, use ``StorageLevel.MEMORY_AND_DISK_2`` instead."""

python/pyspark/streaming/context.py

@@ -258,7 +258,7 @@ def checkpoint(self, directory):
         """
         self._jssc.checkpoint(directory)
 
-    def socketTextStream(self, hostname, port, storageLevel=StorageLevel.MEMORY_AND_DISK_SER_2):
+    def socketTextStream(self, hostname, port, storageLevel=StorageLevel.MEMORY_AND_DISK_2):
         """
         Create an input from TCP source hostname:port. Data is received using
         a TCP socket and receive byte is interpreted as UTF8 encoded ``\\n`` delimited

python/pyspark/streaming/dstream.py

@@ -208,10 +208,10 @@ def func(iterator):
     def cache(self):
         """
         Persist the RDDs of this DStream with the default storage level
-        (C{MEMORY_ONLY_SER}).
+        (C{MEMORY_ONLY}).
         """
         self.is_cached = True
-        self.persist(StorageLevel.MEMORY_ONLY_SER)
+        self.persist(StorageLevel.MEMORY_ONLY)
         return self
 
     def persist(self, storageLevel):

python/pyspark/streaming/flume.py

@@ -40,7 +40,7 @@ class FlumeUtils(object):
 
     @staticmethod
     def createStream(ssc, hostname, port,
-                     storageLevel=StorageLevel.MEMORY_AND_DISK_SER_2,
+                     storageLevel=StorageLevel.MEMORY_AND_DISK_2,
                      enableDecompression=False,
                      bodyDecoder=utf8_decoder):
         """
@@ -70,7 +70,7 @@ def createStream(ssc, hostname, port,
 
     @staticmethod
     def createPollingStream(ssc, addresses,
-                            storageLevel=StorageLevel.MEMORY_AND_DISK_SER_2,
+                            storageLevel=StorageLevel.MEMORY_AND_DISK_2,
                             maxBatchSize=1000,
                             parallelism=5,
                             bodyDecoder=utf8_decoder):

python/pyspark/streaming/kafka.py

@@ -40,7 +40,7 @@ class KafkaUtils(object):
 
     @staticmethod
     def createStream(ssc, zkQuorum, groupId, topics, kafkaParams=None,
-                     storageLevel=StorageLevel.MEMORY_AND_DISK_SER_2,
+                     storageLevel=StorageLevel.MEMORY_AND_DISK_2,
                      keyDecoder=utf8_decoder, valueDecoder=utf8_decoder):
         """
         Create an input stream that pulls messages from a Kafka Broker.

python/pyspark/streaming/mqtt.py

@@ -28,7 +28,7 @@ class MQTTUtils(object):
 
     @staticmethod
     def createStream(ssc, brokerUrl, topic,
-                     storageLevel=StorageLevel.MEMORY_AND_DISK_SER_2):
+                     storageLevel=StorageLevel.MEMORY_AND_DISK_2):
         """
         Create an input stream that pulls messages from a Mqtt Broker.