jobWaiter.synchronized before jobWaiter.wait

core/src/main/scala/org/apache/spark/FutureAction.scala

@@ -99,7 +99,7 @@ class SimpleFutureAction[T] private[spark](jobWaiter: JobWaiter[_], resultFunc:
   override def ready(atMost: Duration)(implicit permit: CanAwait): SimpleFutureAction.this.type = {
     if (!atMost.isFinite()) {
       awaitResult()
-    } else {
+    } else jobWaiter.synchronized {
       val finishTime = System.currentTimeMillis() + atMost.toMillis
       while (!isCompleted) {
         val time = System.currentTimeMillis()

core/src/main/scala/org/apache/spark/scheduler/JobWaiter.scala

@@ -31,6 +31,7 @@ private[spark] class JobWaiter[T](
   private var finishedTasks = 0
 
   // Is the job as a whole finished (succeeded or failed)?
+  @volatile
   private var _jobFinished = totalTasks == 0
 
   def jobFinished = _jobFinished