From 82a06afd76bcb61319895e642c5a5f83a3ff3c61 Mon Sep 17 00:00:00 2001
From: zouchenjun <youfu.zcj@alibaba-inc.com>
Date: Thu, 9 Apr 2020 19:01:46 +0800
Subject: [PATCH] reverse preferred location to make schedule more even

---
 .../main/scala/org/apache/spark/scheduler/TaskSetManager.scala  | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/core/src/main/scala/org/apache/spark/scheduler/TaskSetManager.scala b/core/src/main/scala/org/apache/spark/scheduler/TaskSetManager.scala
index 2c792338b5295..cddea43150b0a 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/TaskSetManager.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/TaskSetManager.scala
@@ -240,7 +240,7 @@ private[spark] class TaskSetManager(
     // A zombie TaskSetManager may reach here while handling failed task.
     if (isZombie) return
     val pendingTaskSetToAddTo = if (speculatable) pendingSpeculatableTasks else pendingTasks
-    for (loc <- tasks(index).preferredLocations) {
+    for (loc <- tasks(index).preferredLocations.reverse) {
       loc match {
         case e: ExecutorCacheTaskLocation =>
           pendingTaskSetToAddTo.forExecutor.getOrElseUpdate(e.executorId, new ArrayBuffer) += index