From 2180c8718895f1773a9906ea0ddd49171c468e0b Mon Sep 17 00:00:00 2001
From: Reynold Xin <rxin@apache.org>
Date: Sat, 11 Jan 2014 13:36:37 -0800
Subject: Stop SparkListenerBus daemon thread when DAGScheduler is stopped.

---
 .../scala/org/apache/spark/scheduler/DAGScheduler.scala   |  4 +++-
 .../scala/org/apache/spark/scheduler/SparkListener.scala  |  3 +++
 .../org/apache/spark/scheduler/SparkListenerBus.scala     | 15 +++++++++++----
 3 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/core/src/main/scala/org/apache/spark/scheduler/DAGScheduler.scala b/core/src/main/scala/org/apache/spark/scheduler/DAGScheduler.scala
index 38b536023b..7046c06d20 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/DAGScheduler.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/DAGScheduler.scala
@@ -133,7 +133,8 @@ class DAGScheduler(
 
   private[spark] val stageToInfos = new TimeStampedHashMap[Stage, StageInfo]
 
-  private[spark] val listenerBus = new SparkListenerBus()
+  // An async scheduler event bus. The bus should be stopped when DAGSCheduler is stopped.
+  private[spark] val listenerBus = new SparkListenerBus
 
   // Contains the locations that each RDD's partitions are cached on
   private val cacheLocs = new HashMap[Int, Array[Seq[TaskLocation]]]
@@ -1121,5 +1122,6 @@ class DAGScheduler(
     }
     metadataCleaner.cancel()
     taskSched.stop()
+    listenerBus.stop()
   }
 }
diff --git a/core/src/main/scala/org/apache/spark/scheduler/SparkListener.scala b/core/src/main/scala/org/apache/spark/scheduler/SparkListener.scala
index 627995c826..55a40a92c9 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/SparkListener.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/SparkListener.scala
@@ -43,6 +43,9 @@ case class SparkListenerJobStart(job: ActiveJob, stageIds: Array[Int], propertie
 case class SparkListenerJobEnd(job: ActiveJob, jobResult: JobResult)
      extends SparkListenerEvents
 
+/** An event used in the listener to shutdown the listener daemon thread. */
+private[scheduler] case object SparkListenerShutdown extends SparkListenerEvents
+
 trait SparkListener {
   /**
    * Called when a stage is completed, with information on the completed stage
diff --git a/core/src/main/scala/org/apache/spark/scheduler/SparkListenerBus.scala b/core/src/main/scala/org/apache/spark/scheduler/SparkListenerBus.scala
index e7defd768b..fc637884e2 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/SparkListenerBus.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/SparkListenerBus.scala
@@ -24,15 +24,17 @@ import scala.collection.mutable.{ArrayBuffer, SynchronizedBuffer}
 import org.apache.spark.Logging
 
 /** Asynchronously passes SparkListenerEvents to registered SparkListeners. */
-private[spark] class SparkListenerBus() extends Logging {
-  private val sparkListeners = new ArrayBuffer[SparkListener]() with SynchronizedBuffer[SparkListener]
+private[spark] class SparkListenerBus extends Logging {
+  private val sparkListeners = new ArrayBuffer[SparkListener] with SynchronizedBuffer[SparkListener]
 
   /* Cap the capacity of the SparkListenerEvent queue so we get an explicit error (rather than
    * an OOM exception) if it's perpetually being added to more quickly than it's being drained. */
-  private val EVENT_QUEUE_CAPACITY = 10000 
+  private val EVENT_QUEUE_CAPACITY = 10000
   private val eventQueue = new LinkedBlockingQueue[SparkListenerEvents](EVENT_QUEUE_CAPACITY)
   private var queueFullErrorMessageLogged = false
 
+  // Create a new daemon thread to listen for events. This thread is stopped when it receives
+  // a SparkListenerShutdown event, using the stop method.
   new Thread("SparkListenerBus") {
     setDaemon(true)
     override def run() {
@@ -53,6 +55,9 @@ private[spark] class SparkListenerBus() extends Logging {
             sparkListeners.foreach(_.onTaskGettingResult(taskGettingResult))
           case taskEnd: SparkListenerTaskEnd =>
             sparkListeners.foreach(_.onTaskEnd(taskEnd))
+          case SparkListenerShutdown =>
+            // Get out of the while loop and shutdown the daemon thread
+            return
           case _ =>
         }
       }
@@ -80,7 +85,7 @@ private[spark] class SparkListenerBus() extends Logging {
    */
   def waitUntilEmpty(timeoutMillis: Int): Boolean = {
     val finishTime = System.currentTimeMillis + timeoutMillis
-    while (!eventQueue.isEmpty()) {
+    while (!eventQueue.isEmpty) {
       if (System.currentTimeMillis > finishTime) {
         return false
       }
@@ -90,4 +95,6 @@ private[spark] class SparkListenerBus() extends Logging {
     }
     return true
   }
+
+  def stop(): Unit = post(SparkListenerShutdown)
 }
-- 
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