Spark 1271: Co-Group and Group-By should pass Iterable[X]

Author: Holden Karau <holden@pigscanfly.ca>

Closes #242 from holdenk/spark-1320-cogroupandgroupshouldpassiterator and squashes the following commits:

f289536 [Holden Karau] Fix bad merge, should have been Iterable rather than Iterator
77048f8 [Holden Karau] Fix merge up to master
d3fe909 [Holden Karau] use toSeq instead
7a092a3 [Holden Karau] switch resultitr to resultiterable
eb06216 [Holden Karau] maybe I should have had a coffee first. use correct import for guava iterables
c5075aa [Holden Karau] If guava 14 had iterables
2d06e10 [Holden Karau] Fix Java 8 cogroup tests for the new API
11e730c [Holden Karau] Fix streaming tests
66b583d [Holden Karau] Fix the core test suite to compile
4ed579b [Holden Karau] Refactor from iterator to iterable
d052c07 [Holden Karau] Python tests now pass with iterator pandas
3bcd81d [Holden Karau] Revert "Try and make pickling list iterators work"
cd1e81c [Holden Karau] Try and make pickling list iterators work
c60233a [Holden Karau] Start investigating moving to iterators for python API like the Java/Scala one. tl;dr: We will have to write our own iterator since the default one doesn't pickle well
88a5cef [Holden Karau] Fix cogroup test in JavaAPISuite for streaming
a5ee714 [Holden Karau] oops, was checking wrong iterator
e687f21 [Holden Karau] Fix groupbykey test in JavaAPISuite of streaming
ec8cc3e [Holden Karau] Fix test issues\!
4b0eeb9 [Holden Karau] Switch cast in PairDStreamFunctions
fa395c9 [Holden Karau] Revert "Add a join based on the problem in SVD"
ec99e32 [Holden Karau] Revert "Revert this but for now put things in list pandas"
b692868 [Holden Karau] Revert
7e533f7 [Holden Karau] Fix the bug
8a5153a [Holden Karau] Revert me, but we have some stuff to debug
b4e86a9 [Holden Karau] Add a join based on the problem in SVD
c4510e2 [Holden Karau] Revert this but for now put things in list pandas
b4e0b1d [Holden Karau] Fix style issues
71e8b9f [Holden Karau] I really need to stop calling size on iterators, it is the path of sadness.
b1ae51a [Holden Karau] Fix some of the types in the streaming JavaAPI suite. Probably still needs more work
37888ec [Holden Karau] core/tests now pass
249abde [Holden Karau] org.apache.spark.rdd.PairRDDFunctionsSuite passes
6698186 [Holden Karau] Revert "I think this might be a bad rabbit hole. Started work to make CoGroupedRDD use iterator and then went crazy"
fe992fe [Holden Karau] hmmm try and fix up basic operation suite
172705c [Holden Karau] Fix Java API suite
caafa63 [Holden Karau] I think this might be a bad rabbit hole. Started work to make CoGroupedRDD use iterator and then went crazy
88b3329 [Holden Karau] Fix groupbykey to actually give back an iterator
4991af6 [Holden Karau] Fix some tests
be50246 [Holden Karau] Calling size on an iterator is not so good if we want to use it after
687ffbc [Holden Karau] This is the it compiles point of replacing Seq with Iterator and JList with JIterator in the groupby and cogroup signatures

4 files changed, 46 insertions, 41 deletions

diff --git a/core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala b/core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala
index 9596dbaf75..e6c5d85917 100644
--- a/core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala
+++ b/core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala
@@ -18,6 +18,7 @@
 package org.apache.spark.api.java
 
 import java.util.{Comparator, List => JList}
+import java.lang.{Iterable => JIterable}
 
 import scala.collection.JavaConversions._
 import scala.reflect.ClassTag
@@ -250,14 +251,14 @@ class JavaPairRDD[K, V](val rdd: RDD[(K, V)])
    * Group the values for each key in the RDD into a single sequence. Allows controlling the
    * partitioning of the resulting key-value pair RDD by passing a Partitioner.
    */
-  def groupByKey(partitioner: Partitioner): JavaPairRDD[K, JList[V]] =
+  def groupByKey(partitioner: Partitioner): JavaPairRDD[K, JIterable[V]] =
     fromRDD(groupByResultToJava(rdd.groupByKey(partitioner)))
 
   /**
    * Group the values for each key in the RDD into a single sequence. Hash-partitions the
    * resulting RDD with into `numPartitions` partitions.
    */
-  def groupByKey(numPartitions: Int): JavaPairRDD[K, JList[V]] =
+  def groupByKey(numPartitions: Int): JavaPairRDD[K, JIterable[V]] =
     fromRDD(groupByResultToJava(rdd.groupByKey(numPartitions)))
 
   /**
@@ -367,7 +368,7 @@ class JavaPairRDD[K, V](val rdd: RDD[(K, V)])
    * Group the values for each key in the RDD into a single sequence. Hash-partitions the
    * resulting RDD with the existing partitioner/parallelism level.
    */
-  def groupByKey(): JavaPairRDD[K, JList[V]] =
+  def groupByKey(): JavaPairRDD[K, JIterable[V]] =
     fromRDD(groupByResultToJava(rdd.groupByKey()))
 
   /**
@@ -462,7 +463,7 @@ class JavaPairRDD[K, V](val rdd: RDD[(K, V)])
    * list of values for that key in `this` as well as `other`.
    */
   def cogroup[W](other: JavaPairRDD[K, W], partitioner: Partitioner)
-  : JavaPairRDD[K, (JList[V], JList[W])] =
+  : JavaPairRDD[K, (JIterable[V], JIterable[W])] =
     fromRDD(cogroupResultToJava(rdd.cogroup(other, partitioner)))
 
   /**
@@ -470,14 +471,14 @@ class JavaPairRDD[K, V](val rdd: RDD[(K, V)])
    * tuple with the list of values for that key in `this`, `other1` and `other2`.
    */
   def cogroup[W1, W2](other1: JavaPairRDD[K, W1], other2: JavaPairRDD[K, W2],
-      partitioner: Partitioner): JavaPairRDD[K, (JList[V], JList[W1], JList[W2])] =
+      partitioner: Partitioner): JavaPairRDD[K, (JIterable[V], JIterable[W1], JIterable[W2])] =
     fromRDD(cogroupResult2ToJava(rdd.cogroup(other1, other2, partitioner)))
 
   /**
    * For each key k in `this` or `other`, return a resulting RDD that contains a tuple with the
    * list of values for that key in `this` as well as `other`.
    */
-  def cogroup[W](other: JavaPairRDD[K, W]): JavaPairRDD[K, (JList[V], JList[W])] =
+  def cogroup[W](other: JavaPairRDD[K, W]): JavaPairRDD[K, (JIterable[V], JIterable[W])] =
     fromRDD(cogroupResultToJava(rdd.cogroup(other)))
 
   /**
@@ -485,7 +486,7 @@ class JavaPairRDD[K, V](val rdd: RDD[(K, V)])
    * tuple with the list of values for that key in `this`, `other1` and `other2`.
    */
   def cogroup[W1, W2](other1: JavaPairRDD[K, W1], other2: JavaPairRDD[K, W2])
-  : JavaPairRDD[K, (JList[V], JList[W1], JList[W2])] =
+  : JavaPairRDD[K, (JIterable[V], JIterable[W1], JIterable[W2])] =
     fromRDD(cogroupResult2ToJava(rdd.cogroup(other1, other2)))
 
   /**
@@ -493,7 +494,7 @@ class JavaPairRDD[K, V](val rdd: RDD[(K, V)])
    * list of values for that key in `this` as well as `other`.
    */
   def cogroup[W](other: JavaPairRDD[K, W], numPartitions: Int)
-  : JavaPairRDD[K, (JList[V], JList[W])] =
+  : JavaPairRDD[K, (JIterable[V], JIterable[W])] =
     fromRDD(cogroupResultToJava(rdd.cogroup(other, numPartitions)))
 
   /**
@@ -501,16 +502,16 @@ class JavaPairRDD[K, V](val rdd: RDD[(K, V)])
    * tuple with the list of values for that key in `this`, `other1` and `other2`.
    */
   def cogroup[W1, W2](other1: JavaPairRDD[K, W1], other2: JavaPairRDD[K, W2], numPartitions: Int)
-  : JavaPairRDD[K, (JList[V], JList[W1], JList[W2])] =
+  : JavaPairRDD[K, (JIterable[V], JIterable[W1], JIterable[W2])] =
     fromRDD(cogroupResult2ToJava(rdd.cogroup(other1, other2, numPartitions)))
 
   /** Alias for cogroup. */
-  def groupWith[W](other: JavaPairRDD[K, W]): JavaPairRDD[K, (JList[V], JList[W])] =
+  def groupWith[W](other: JavaPairRDD[K, W]): JavaPairRDD[K, (JIterable[V], JIterable[W])] =
     fromRDD(cogroupResultToJava(rdd.groupWith(other)))
 
   /** Alias for cogroup. */
   def groupWith[W1, W2](other1: JavaPairRDD[K, W1], other2: JavaPairRDD[K, W2])
-  : JavaPairRDD[K, (JList[V], JList[W1], JList[W2])] =
+  : JavaPairRDD[K, (JIterable[V], JIterable[W1], JIterable[W2])] =
     fromRDD(cogroupResult2ToJava(rdd.groupWith(other1, other2)))
 
   /**
@@ -695,21 +696,22 @@ class JavaPairRDD[K, V](val rdd: RDD[(K, V)])
 
 object JavaPairRDD {
   private[spark]
-  def groupByResultToJava[K: ClassTag, T](rdd: RDD[(K, Seq[T])]): RDD[(K, JList[T])] = {
-    rddToPairRDDFunctions(rdd).mapValues(seqAsJavaList)
+  def groupByResultToJava[K: ClassTag, T](rdd: RDD[(K, Iterable[T])]): RDD[(K, JIterable[T])] = {
+    rddToPairRDDFunctions(rdd).mapValues(asJavaIterable)
   }
 
   private[spark]
   def cogroupResultToJava[K: ClassTag, V, W](
-      rdd: RDD[(K, (Seq[V], Seq[W]))]): RDD[(K, (JList[V], JList[W]))] = {
-    rddToPairRDDFunctions(rdd).mapValues(x => (seqAsJavaList(x._1), seqAsJavaList(x._2)))
+      rdd: RDD[(K, (Iterable[V], Iterable[W]))]): RDD[(K, (JIterable[V], JIterable[W]))] = {
+    rddToPairRDDFunctions(rdd).mapValues(x => (asJavaIterable(x._1), asJavaIterable(x._2)))
   }
 
   private[spark]
   def cogroupResult2ToJava[K: ClassTag, V, W1, W2](
-      rdd: RDD[(K, (Seq[V], Seq[W1], Seq[W2]))]): RDD[(K, (JList[V], JList[W1], JList[W2]))] = {
+      rdd: RDD[(K, (Iterable[V], Iterable[W1], Iterable[W2]))])
+      : RDD[(K, (JIterable[V], JIterable[W1], JIterable[W2]))] = {
     rddToPairRDDFunctions(rdd)
-      .mapValues(x => (seqAsJavaList(x._1), seqAsJavaList(x._2), seqAsJavaList(x._3)))
+      .mapValues(x => (asJavaIterable(x._1), asJavaIterable(x._2), asJavaIterable(x._3)))
   }
 
   def fromRDD[K: ClassTag, V: ClassTag](rdd: RDD[(K, V)]): JavaPairRDD[K, V] = {
diff --git a/core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala b/core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala
index 6e8ec8e0c7..ae577b500c 100644
--- a/core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala
+++ b/core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.api.java
 
-import java.util.{Comparator, Iterator => JIterator, List => JList}
+import java.util.{Comparator, List => JList, Iterator => JIterator}
 import java.lang.{Iterable => JIterable}
 
 import scala.collection.JavaConversions._
@@ -204,7 +204,7 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
    * Return an RDD of grouped elements. Each group consists of a key and a sequence of elements
    * mapping to that key.
    */
-  def groupBy[K](f: JFunction[T, K]): JavaPairRDD[K, JList[T]] = {
+  def groupBy[K](f: JFunction[T, K]): JavaPairRDD[K, JIterable[T]] = {
     implicit val ctagK: ClassTag[K] = fakeClassTag
     implicit val ctagV: ClassTag[JList[T]] = fakeClassTag
     JavaPairRDD.fromRDD(groupByResultToJava(rdd.groupBy(f)(fakeClassTag)))
@@ -214,7 +214,7 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
    * Return an RDD of grouped elements. Each group consists of a key and a sequence of elements
    * mapping to that key.
    */
-  def groupBy[K](f: JFunction[T, K], numPartitions: Int): JavaPairRDD[K, JList[T]] = {
+  def groupBy[K](f: JFunction[T, K], numPartitions: Int): JavaPairRDD[K, JIterable[T]] = {
     implicit val ctagK: ClassTag[K] = fakeClassTag
     implicit val ctagV: ClassTag[JList[T]] = fakeClassTag
     JavaPairRDD.fromRDD(groupByResultToJava(rdd.groupBy(f, numPartitions)(fakeClassTag[K])))
diff --git a/core/src/main/scala/org/apache/spark/rdd/PairRDDFunctions.scala b/core/src/main/scala/org/apache/spark/rdd/PairRDDFunctions.scala
index 14386ff5b9..a92a84b534 100644
--- a/core/src/main/scala/org/apache/spark/rdd/PairRDDFunctions.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/PairRDDFunctions.scala
@@ -261,7 +261,7 @@ class PairRDDFunctions[K: ClassTag, V: ClassTag](self: RDD[(K, V)])
    * Group the values for each key in the RDD into a single sequence. Allows controlling the
    * partitioning of the resulting key-value pair RDD by passing a Partitioner.
    */
-  def groupByKey(partitioner: Partitioner): RDD[(K, Seq[V])] = {
+  def groupByKey(partitioner: Partitioner): RDD[(K, Iterable[V])] = {
     // groupByKey shouldn't use map side combine because map side combine does not
     // reduce the amount of data shuffled and requires all map side data be inserted
     // into a hash table, leading to more objects in the old gen.
@@ -270,14 +270,14 @@ class PairRDDFunctions[K: ClassTag, V: ClassTag](self: RDD[(K, V)])
     def mergeCombiners(c1: ArrayBuffer[V], c2: ArrayBuffer[V]) = c1 ++ c2
     val bufs = combineByKey[ArrayBuffer[V]](
       createCombiner _, mergeValue _, mergeCombiners _, partitioner, mapSideCombine=false)
-    bufs.asInstanceOf[RDD[(K, Seq[V])]]
+    bufs.mapValues(_.toIterable)
   }
 
   /**
    * Group the values for each key in the RDD into a single sequence. Hash-partitions the
    * resulting RDD with into `numPartitions` partitions.
    */
-  def groupByKey(numPartitions: Int): RDD[(K, Seq[V])] = {
+  def groupByKey(numPartitions: Int): RDD[(K, Iterable[V])] = {
     groupByKey(new HashPartitioner(numPartitions))
   }
 
@@ -298,7 +298,7 @@ class PairRDDFunctions[K: ClassTag, V: ClassTag](self: RDD[(K, V)])
    */
   def join[W](other: RDD[(K, W)], partitioner: Partitioner): RDD[(K, (V, W))] = {
     this.cogroup(other, partitioner).flatMapValues { case (vs, ws) =>
-      for (v <- vs.iterator; w <- ws.iterator) yield (v, w)
+      for (v <- vs; w <- ws) yield (v, w)
     }
   }
 
@@ -311,9 +311,9 @@ class PairRDDFunctions[K: ClassTag, V: ClassTag](self: RDD[(K, V)])
   def leftOuterJoin[W](other: RDD[(K, W)], partitioner: Partitioner): RDD[(K, (V, Option[W]))] = {
     this.cogroup(other, partitioner).flatMapValues { case (vs, ws) =>
       if (ws.isEmpty) {
-        vs.iterator.map(v => (v, None))
+        vs.map(v => (v, None))
       } else {
-        for (v <- vs.iterator; w <- ws.iterator) yield (v, Some(w))
+        for (v <- vs; w <- ws) yield (v, Some(w))
       }
     }
   }
@@ -328,9 +328,9 @@ class PairRDDFunctions[K: ClassTag, V: ClassTag](self: RDD[(K, V)])
       : RDD[(K, (Option[V], W))] = {
     this.cogroup(other, partitioner).flatMapValues { case (vs, ws) =>
       if (vs.isEmpty) {
-        ws.iterator.map(w => (None, w))
+        ws.map(w => (None, w))
       } else {
-        for (v <- vs.iterator; w <- ws.iterator) yield (Some(v), w)
+        for (v <- vs; w <- ws) yield (Some(v), w)
       }
     }
   }
@@ -358,7 +358,7 @@ class PairRDDFunctions[K: ClassTag, V: ClassTag](self: RDD[(K, V)])
    * Group the values for each key in the RDD into a single sequence. Hash-partitions the
    * resulting RDD with the existing partitioner/parallelism level.
    */
-  def groupByKey(): RDD[(K, Seq[V])] = {
+  def groupByKey(): RDD[(K, Iterable[V])] = {
     groupByKey(defaultPartitioner(self))
   }
 
@@ -453,7 +453,8 @@ class PairRDDFunctions[K: ClassTag, V: ClassTag](self: RDD[(K, V)])
    * For each key k in `this` or `other`, return a resulting RDD that contains a tuple with the
    * list of values for that key in `this` as well as `other`.
    */
-  def cogroup[W](other: RDD[(K, W)], partitioner: Partitioner): RDD[(K, (Seq[V], Seq[W]))] = {
+  def cogroup[W](other: RDD[(K, W)], partitioner: Partitioner)
+      : RDD[(K, (Iterable[V], Iterable[W]))]  = {
     if (partitioner.isInstanceOf[HashPartitioner] && getKeyClass().isArray) {
       throw new SparkException("Default partitioner cannot partition array keys.")
     }
@@ -468,13 +469,15 @@ class PairRDDFunctions[K: ClassTag, V: ClassTag](self: RDD[(K, V)])
    * tuple with the list of values for that key in `this`, `other1` and `other2`.
    */
   def cogroup[W1, W2](other1: RDD[(K, W1)], other2: RDD[(K, W2)], partitioner: Partitioner)
-      : RDD[(K, (Seq[V], Seq[W1], Seq[W2]))] = {
+      : RDD[(K, (Iterable[V], Iterable[W1], Iterable[W2]))] = {
     if (partitioner.isInstanceOf[HashPartitioner] && getKeyClass().isArray) {
       throw new SparkException("Default partitioner cannot partition array keys.")
     }
     val cg = new CoGroupedRDD[K](Seq(self, other1, other2), partitioner)
     cg.mapValues { case Seq(vs, w1s, w2s) =>
-      (vs.asInstanceOf[Seq[V]], w1s.asInstanceOf[Seq[W1]], w2s.asInstanceOf[Seq[W2]])
+      (vs.asInstanceOf[Seq[V]],
+       w1s.asInstanceOf[Seq[W1]],
+       w2s.asInstanceOf[Seq[W2]])
     }
   }
 
@@ -482,7 +485,7 @@ class PairRDDFunctions[K: ClassTag, V: ClassTag](self: RDD[(K, V)])
    * For each key k in `this` or `other`, return a resulting RDD that contains a tuple with the
    * list of values for that key in `this` as well as `other`.
    */
-  def cogroup[W](other: RDD[(K, W)]): RDD[(K, (Seq[V], Seq[W]))] = {
+  def cogroup[W](other: RDD[(K, W)]): RDD[(K, (Iterable[V], Iterable[W]))] = {
     cogroup(other, defaultPartitioner(self, other))
   }
 
@@ -491,7 +494,7 @@ class PairRDDFunctions[K: ClassTag, V: ClassTag](self: RDD[(K, V)])
    * tuple with the list of values for that key in `this`, `other1` and `other2`.
    */
   def cogroup[W1, W2](other1: RDD[(K, W1)], other2: RDD[(K, W2)])
-      : RDD[(K, (Seq[V], Seq[W1], Seq[W2]))] = {
+      : RDD[(K, (Iterable[V], Iterable[W1], Iterable[W2]))] = {
     cogroup(other1, other2, defaultPartitioner(self, other1, other2))
   }
 
@@ -499,7 +502,7 @@ class PairRDDFunctions[K: ClassTag, V: ClassTag](self: RDD[(K, V)])
    * For each key k in `this` or `other`, return a resulting RDD that contains a tuple with the
    * list of values for that key in `this` as well as `other`.
    */
-  def cogroup[W](other: RDD[(K, W)], numPartitions: Int): RDD[(K, (Seq[V], Seq[W]))] = {
+  def cogroup[W](other: RDD[(K, W)], numPartitions: Int): RDD[(K, (Iterable[V], Iterable[W]))] = {
     cogroup(other, new HashPartitioner(numPartitions))
   }
 
@@ -508,18 +511,18 @@ class PairRDDFunctions[K: ClassTag, V: ClassTag](self: RDD[(K, V)])
    * tuple with the list of values for that key in `this`, `other1` and `other2`.
    */
   def cogroup[W1, W2](other1: RDD[(K, W1)], other2: RDD[(K, W2)], numPartitions: Int)
-      : RDD[(K, (Seq[V], Seq[W1], Seq[W2]))] = {
+      : RDD[(K, (Iterable[V], Iterable[W1], Iterable[W2]))] = {
     cogroup(other1, other2, new HashPartitioner(numPartitions))
   }
 
   /** Alias for cogroup. */
-  def groupWith[W](other: RDD[(K, W)]): RDD[(K, (Seq[V], Seq[W]))] = {
+  def groupWith[W](other: RDD[(K, W)]): RDD[(K, (Iterable[V], Iterable[W]))] = {
     cogroup(other, defaultPartitioner(self, other))
   }
 
   /** Alias for cogroup. */
   def groupWith[W1, W2](other1: RDD[(K, W1)], other2: RDD[(K, W2)])
-      : RDD[(K, (Seq[V], Seq[W1], Seq[W2]))] = {
+      : RDD[(K, (Iterable[V], Iterable[W1], Iterable[W2]))] = {
     cogroup(other1, other2, defaultPartitioner(self, other1, other2))
   }
 
diff --git a/core/src/main/scala/org/apache/spark/rdd/RDD.scala b/core/src/main/scala/org/apache/spark/rdd/RDD.scala
index bf3c57ad41..74fa2a4fcd 100644
--- a/core/src/main/scala/org/apache/spark/rdd/RDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/RDD.scala
@@ -438,20 +438,20 @@ abstract class RDD[T: ClassTag](
   /**
    * Return an RDD of grouped items.
    */
-  def groupBy[K: ClassTag](f: T => K): RDD[(K, Seq[T])] =
+  def groupBy[K: ClassTag](f: T => K): RDD[(K, Iterable[T])] =
     groupBy[K](f, defaultPartitioner(this))
 
   /**
    * Return an RDD of grouped elements. Each group consists of a key and a sequence of elements
    * mapping to that key.
    */
-  def groupBy[K: ClassTag](f: T => K, numPartitions: Int): RDD[(K, Seq[T])] =
+  def groupBy[K: ClassTag](f: T => K, numPartitions: Int): RDD[(K, Iterable[T])] =
     groupBy(f, new HashPartitioner(numPartitions))
 
   /**
    * Return an RDD of grouped items.
    */
-  def groupBy[K: ClassTag](f: T => K, p: Partitioner): RDD[(K, Seq[T])] = {
+  def groupBy[K: ClassTag](f: T => K, p: Partitioner): RDD[(K, Iterable[T])] = {
     val cleanF = sc.clean(f)
     this.map(t => (cleanF(t), t)).groupByKey(p)
   }