Merge pull request alteryx#187 from aarondav/example-bcast-test

Enable the Broadcast examples to work in a cluster setting

Since they rely on println to display results, we need to first collect those results to the driver to have them actually display locally.

This issue came up on the mailing lists [here](http://mail-archives.apache.org/mod_mbox/incubator-spark-user/201311.mbox/%3C2013111909591557147628%40ict.ac.cn%3E).

examples/src/main/scala/org/apache/spark/examples/BroadcastTest.scala

@@ -32,13 +32,13 @@ object BroadcastTest {
     System.setProperty("spark.broadcast.factory", "org.apache.spark.broadcast." + bcName + "BroadcastFactory")
     System.setProperty("spark.broadcast.blockSize", blockSize)
 
-    val sc = new SparkContext(args(0), "Broadcast Test 2",
+    val sc = new SparkContext(args(0), "Broadcast Test",
       System.getenv("SPARK_HOME"), Seq(System.getenv("SPARK_EXAMPLES_JAR")))
 
     val slices = if (args.length > 1) args(1).toInt else 2
     val num = if (args.length > 2) args(2).toInt else 1000000
 
-    var arr1 = new Array[Int](num)
+    val arr1 = new Array[Int](num)
     for (i <- 0 until arr1.length) {
       arr1(i) = i
     }
@@ -48,9 +48,9 @@ object BroadcastTest {
       println("===========")
       val startTime = System.nanoTime
       val barr1 = sc.broadcast(arr1)
-      sc.parallelize(1 to 10, slices).foreach {
-        i => println(barr1.value.size)
-      }
+      val observedSizes = sc.parallelize(1 to 10, slices).map(_ => barr1.value.size)
+      // Collect the small RDD so we can print the observed sizes locally.
+      observedSizes.collect().foreach(i => println(i))
       println("Iteration %d took %.0f milliseconds".format(i, (System.nanoTime - startTime) / 1E6))
     }
 

examples/src/main/scala/org/apache/spark/examples/MultiBroadcastTest.scala

@@ -18,35 +18,38 @@
 package org.apache.spark.examples
 
 import org.apache.spark.SparkContext
+import org.apache.spark.rdd.RDD
 
 object MultiBroadcastTest {
   def main(args: Array[String]) {
     if (args.length == 0) {
-      System.err.println("Usage: BroadcastTest <master> [<slices>] [numElem]")
+      System.err.println("Usage: MultiBroadcastTest <master> [<slices>] [numElem]")
       System.exit(1)
     }
 
-    val sc = new SparkContext(args(0), "Broadcast Test",
+    val sc = new SparkContext(args(0), "Multi-Broadcast Test",
       System.getenv("SPARK_HOME"), Seq(System.getenv("SPARK_EXAMPLES_JAR")))
 
     val slices = if (args.length > 1) args(1).toInt else 2
     val num = if (args.length > 2) args(2).toInt else 1000000
 
-    var arr1 = new Array[Int](num)
+    val arr1 = new Array[Int](num)
     for (i <- 0 until arr1.length) {
       arr1(i) = i
     }
 
-    var arr2 = new Array[Int](num)
+    val arr2 = new Array[Int](num)
     for (i <- 0 until arr2.length) {
       arr2(i) = i
     }
 
     val barr1 = sc.broadcast(arr1)
     val barr2 = sc.broadcast(arr2)
-    sc.parallelize(1 to 10, slices).foreach {
-      i => println(barr1.value.size + barr2.value.size)
+    val observedSizes: RDD[(Int, Int)] = sc.parallelize(1 to 10, slices).map { _ =>
+      (barr1.value.size, barr2.value.size)
     }
+    // Collect the small RDD so we can print the observed sizes locally.
+    observedSizes.collect().foreach(i => println(i))
 
     System.exit(0)
   }