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Add an interface to zip iterators of multiple RDDs

The current code supports 2, 3 or 4 arguments but can be extended
to more arguments if required.
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shivaram committed Apr 26, 2013
1 parent 1f20ef2 commit c9c4954d994c5ba824e71c1c5cd8d5de531caf78
@@ -35,6 +35,9 @@ import spark.rdd.ShuffledRDD
import spark.rdd.SubtractedRDD
import spark.rdd.UnionRDD
import spark.rdd.ZippedRDD
+import spark.rdd.MapZippedPartitionsRDD2
+import spark.rdd.MapZippedPartitionsRDD3
+import spark.rdd.MapZippedPartitionsRDD4
import spark.storage.StorageLevel
import SparkContext._
@@ -436,6 +439,25 @@ abstract class RDD[T: ClassManifest](
*/
def zip[U: ClassManifest](other: RDD[U]): RDD[(T, U)] = new ZippedRDD(sc, this, other)
+ def zipAndMapPartitions[B: ClassManifest, V: ClassManifest](
+ f: (Iterator[T], Iterator[B]) => Iterator[V],
+ rdd2: RDD[B]) =
+ new MapZippedPartitionsRDD2(sc, sc.clean(f), this, rdd2)
+
+ def zipAndMapPartitions[B: ClassManifest, C: ClassManifest, V: ClassManifest](
+ f: (Iterator[T], Iterator[B], Iterator[C]) => Iterator[V],
+ rdd2: RDD[B],
+ rdd3: RDD[C]) =
+ new MapZippedPartitionsRDD3(sc, sc.clean(f), this, rdd2, rdd3)
+
+ def zipAndMapPartitions[B: ClassManifest, C: ClassManifest, D: ClassManifest, V: ClassManifest](
+ f: (Iterator[T], Iterator[B], Iterator[C], Iterator[D]) => Iterator[V],
+ rdd2: RDD[B],
+ rdd3: RDD[C],
+ rdd4: RDD[D]) =
+ new MapZippedPartitionsRDD4(sc, sc.clean(f), this, rdd2, rdd3, rdd4)
+
+
// Actions (launch a job to return a value to the user program)
/**
@@ -0,0 +1,118 @@
+package spark.rdd
+
+import spark.{OneToOneDependency, RDD, SparkContext, Partition, TaskContext}
+import java.io.{ObjectOutputStream, IOException}
+
+private[spark] class MapZippedPartition(
+ idx: Int,
+ @transient rdds: Seq[RDD[_]]
+ ) extends Partition {
+
+ override val index: Int = idx
+ var partitionValues = rdds.map(rdd => rdd.partitions(idx))
+ def partitions = partitionValues
+
+ @throws(classOf[IOException])
+ private def writeObject(oos: ObjectOutputStream) {
+ // Update the reference to parent split at the time of task serialization
+ partitionValues = rdds.map(rdd => rdd.partitions(idx))
+ oos.defaultWriteObject()
+ }
+}
+
+abstract class MapZippedPartitionsBaseRDD[V: ClassManifest](
+ sc: SparkContext,
+ var rdds: Seq[RDD[_]])
+ extends RDD[V](sc, rdds.map(x => new OneToOneDependency(x))) {
+
+ override def getPartitions: Array[Partition] = {
+ val sizes = rdds.map(x => x.partitions.size)
+ if (!sizes.forall(x => x == sizes(0))) {
+ throw new IllegalArgumentException("Can't zip RDDs with unequal numbers of partitions")
+ }
+ val array = new Array[Partition](sizes(0))
+ for (i <- 0 until sizes(0)) {
+ array(i) = new MapZippedPartition(i, rdds)
+ }
+ array
+ }
+
+ override def getPreferredLocations(s: Partition): Seq[String] = {
+ val splits = s.asInstanceOf[MapZippedPartition].partitions
+ val preferredLocations = rdds.zip(splits).map(x => x._1.preferredLocations(x._2))
+ preferredLocations.reduce((x, y) => x.intersect(y))
+ }
+
+ override def clearDependencies() {
+ super.clearDependencies()
+ rdds = null
+ }
+}
+
+class MapZippedPartitionsRDD2[A: ClassManifest, B: ClassManifest, V: ClassManifest](
+ sc: SparkContext,
+ f: (Iterator[A], Iterator[B]) => Iterator[V],
+ var rdd1: RDD[A],
+ var rdd2: RDD[B])
+ extends MapZippedPartitionsBaseRDD[V](sc, List(rdd1, rdd2)) {
+
+ override def compute(s: Partition, context: TaskContext): Iterator[V] = {
+ val partitions = s.asInstanceOf[MapZippedPartition].partitions
+ f(rdd1.iterator(partitions(0), context), rdd2.iterator(partitions(1), context))
+ }
+
+ override def clearDependencies() {
+ super.clearDependencies()
+ rdd1 = null
+ rdd2 = null
+ }
+}
+
+class MapZippedPartitionsRDD3[A: ClassManifest, B: ClassManifest, C: ClassManifest, V: ClassManifest](
+ sc: SparkContext,
+ f: (Iterator[A], Iterator[B], Iterator[C]) => Iterator[V],
+ var rdd1: RDD[A],
+ var rdd2: RDD[B],
+ var rdd3: RDD[C])
+ extends MapZippedPartitionsBaseRDD[V](sc, List(rdd1, rdd2, rdd3)) {
+
+ override def compute(s: Partition, context: TaskContext): Iterator[V] = {
+ val partitions = s.asInstanceOf[MapZippedPartition].partitions
+ f(rdd1.iterator(partitions(0), context),
+ rdd2.iterator(partitions(1), context),
+ rdd3.iterator(partitions(2), context))
+ }
+
+ override def clearDependencies() {
+ super.clearDependencies()
+ rdd1 = null
+ rdd2 = null
+ rdd3 = null
+ }
+}
+
+class MapZippedPartitionsRDD4[A: ClassManifest, B: ClassManifest, C: ClassManifest, D:ClassManifest, V: ClassManifest](
+ sc: SparkContext,
+ f: (Iterator[A], Iterator[B], Iterator[C], Iterator[D]) => Iterator[V],
+ var rdd1: RDD[A],
+ var rdd2: RDD[B],
+ var rdd3: RDD[C],
+ var rdd4: RDD[D])
+ extends MapZippedPartitionsBaseRDD[V](sc, List(rdd1, rdd2, rdd3, rdd4)) {
+
+ override def compute(s: Partition, context: TaskContext): Iterator[V] = {
+ val partitions = s.asInstanceOf[MapZippedPartition].partitions
+ f(rdd1.iterator(partitions(0), context),
+ rdd2.iterator(partitions(1), context),
+ rdd3.iterator(partitions(2), context),
+ rdd4.iterator(partitions(3), context))
+ }
+
+ override def clearDependencies() {
+ super.clearDependencies()
+ rdd1 = null
+ rdd2 = null
+ rdd3 = null
+ rdd4 = null
+ }
+}
@@ -0,0 +1,34 @@
+package spark
+
+import scala.collection.immutable.NumericRange
+
+import org.scalatest.FunSuite
+import org.scalatest.prop.Checkers
+import org.scalacheck.Arbitrary._
+import org.scalacheck.Gen
+import org.scalacheck.Prop._
+
+import SparkContext._
+
+
+object MapZippedPartitionsSuite {
+ def procZippedData(i: Iterator[Int], s: Iterator[String], d: Iterator[Double]) : Iterator[Int] = {
+ Iterator(i.toArray.size, s.toArray.size, d.toArray.size)
+ }
+}
+
+class MapZippedPartitionsSuite extends FunSuite with LocalSparkContext {
+ test("print sizes") {
+ sc = new SparkContext("local", "test")
+ val data1 = sc.makeRDD(Array(1, 2, 3, 4), 2)
+ val data2 = sc.makeRDD(Array("1", "2", "3", "4", "5", "6"), 2)
+ val data3 = sc.makeRDD(Array(1.0, 2.0), 2)
+
+ val zippedRDD = data1.zipAndMapPartitions(MapZippedPartitionsSuite.procZippedData, data2, data3)
+
+ val obtainedSizes = zippedRDD.collect()
+ val expectedSizes = Array(2, 3, 1, 2, 3, 1)
+ assert(obtainedSizes.size == 6)
+ assert(obtainedSizes.zip(expectedSizes).forall(x => x._1 == x._2))
+ }
+}

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