Adding test script

core/src/main/scala/spark/ui/UIWorkloadGenerator.scala

+package spark.ui
+
+import scala.util.Random
+
+import spark.SparkContext
+import spark.SparkContext._
+
+/**
+ * Continuously generates jobs that expose various features of the WebUI (internal testing tool).
+ *
+ * Usage: ./run spark.ui.UIWorkloadGenerator [master]
+ */
+private[spark] object UIWorkloadGenerator {
+  val NUM_PARTITIONS = 100
+  val INTER_JOB_WAIT_MS = 500
+
+  def main(args: Array[String]) {
+    val master = args(0)
+    val appName = "Spark UI Tester"
+    val sc = new SparkContext(master, appName)
+
+    // NOTE: Right now there is no easy way for us to show spark.job.annotation for a given phase,
+    //       but we pass it here anyways since it will be useful once we do.
+    def setName(s: String) = {
+      sc.addLocalProperties("spark.job.annotation", s)
+    }
+    val baseData = sc.makeRDD(1 to NUM_PARTITIONS * 10, NUM_PARTITIONS)
+    def nextFloat() = (new Random()).nextFloat()
+
+    val jobs = Seq[(String, () => Long)](
+      ("Count", baseData.count),
+      ("Cache and Count", baseData.map(x => x).cache.count),
+      ("Single Shuffle", baseData.map(x => (x % 10, x)).reduceByKey(_ + _).count),
+      ("Entirely failed phase", baseData.map(x => throw new Exception).count),
+      ("Partially failed phase", {
+        baseData.map{x =>
+          val probFailure = (4.0 / NUM_PARTITIONS)
+          if (nextFloat() < probFailure) {
+            throw new Exception("This is a task failure")
+          }
+          1
+        }.count
+      }),
+      ("Job with delays", baseData.map(x => Thread.sleep(1000)).count)
+    )
+
+    while (true) {
+      for ((desc, job) <- jobs) {
+        try {
+          setName(desc)
+          job()
+          println("Job funished: " + desc)
+        } catch {
+          case e: Exception =>
+            println("Job Failed: " + desc)
+        }
+        Thread.sleep(INTER_JOB_WAIT_MS)
+      }
+    }
+  }
+}