diff --git a/core/src/main/scala/org/apache/spark/deploy/DeployMessage.scala b/core/src/main/scala/org/apache/spark/deploy/DeployMessage.scala
index 1415d625625b1..243d8edb72ed3 100644
--- a/core/src/main/scala/org/apache/spark/deploy/DeployMessage.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/DeployMessage.scala
@@ -88,6 +88,8 @@ private[deploy] object DeployMessages {
 
   case class KillDriver(driverId: String) extends DeployMessage
 
+  case class ApplicationFinished(id: String)
+
   // Worker internal
 
   case object WorkDirCleanup      // Sent to Worker actor periodically for cleaning up app folders
@@ -176,8 +178,4 @@ private[deploy] object DeployMessages {
 
   case object SendHeartbeat
 
-  // Application finished message, used for cleanup
-
-  case class ApplicationFinished(id: String)
-
 }
diff --git a/core/src/main/scala/org/apache/spark/deploy/worker/Worker.scala b/core/src/main/scala/org/apache/spark/deploy/worker/Worker.scala
index 8b560714d374b..3a3db0fb1e548 100755
--- a/core/src/main/scala/org/apache/spark/deploy/worker/Worker.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/worker/Worker.scala
@@ -342,12 +342,15 @@ private[spark] class Worker(
           // Create local dirs for the executor. These are passed to the executor via the
           // SPARK_LOCAL_DIRS environment variable, and deleted by the Worker when the
           // application finishes.
-          val appLocalDirs = appDirectories.get(appId).getOrElse {
-            Utils.getOrCreateLocalRootDirs(conf).map { dir =>
-              Utils.createDirectory(dir).getAbsolutePath()
-            }.toSeq
+          val appLocalDirs = appDirectories.synchronized {
+            val dirs = appDirectories.get(appId).getOrElse {
+              Utils.getOrCreateLocalRootDirs(conf).map { dir =>
+                Utils.createDirectory(dir).getAbsolutePath()
+              }.toSeq
+            }
+            appDirectories(appId) = dirs
+            dirs
           }
-          appDirectories(appId) = appLocalDirs
 
           val manager = new ExecutorRunner(appId, execId, appDesc, cores_, memory_,
             self, workerId, host, sparkHome, executorDir, akkaUrl, conf, appLocalDirs,
@@ -469,13 +472,13 @@ private[spark] class Worker(
     registerWithMaster()
   }
 
-  private def maybeCleanupApplication(id: String): Unit = synchronized {
+  private def maybeCleanupApplication(id: String): Unit = appDirectories.synchronized {
     val shouldCleanup = finishedApps.contains(id) && !executors.values.exists(_.appId == id)
     if (shouldCleanup) {
       finishedApps -= id
-      appDirectories.remove(id).foreach {
+      appDirectories.remove(id).foreach { dirList =>
         logInfo(s"Cleaning up local directories for application $id")
-        _.foreach { dir =>
+        dirList.foreach { dir =>
           Utils.deleteRecursively(new File(dir))
         }
       }