From a0b7abf278c147d3ae7821c6783a85cb972c6ec2 Mon Sep 17 00:00:00 2001
From: Weiwei Yang <wwei@apache.org>
Date: Mon, 7 May 2018 11:33:14 +0800
Subject: [PATCH] YARN-8025.
 UsersManangers#getComputedResourceLimitForActiveUsers throws NPE due to
 preComputedActiveUserLimit is empty. Contributed by Tao Yang.

(Cherry picked from commit 67f239c42f676237290d18ddbbc9aec369267692)
---
 .../resourcemanager/scheduler/capacity/UsersManager.java | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/UsersManager.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/UsersManager.java
index 33f30b00412..b2b6e79704e 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/UsersManager.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/UsersManager.java
@@ -490,11 +490,12 @@ public class UsersManager implements AbstractUsersManager {
       Resource clusterResource, String nodePartition,
       SchedulingMode schedulingMode) {
 
-    Map<SchedulingMode, Resource> userLimitPerSchedulingMode = preComputedActiveUserLimit
-        .get(nodePartition);
+    Map<SchedulingMode, Resource> userLimitPerSchedulingMode;
 
     try {
       writeLock.lock();
+      userLimitPerSchedulingMode =
+          preComputedActiveUserLimit.get(nodePartition);
       if (isRecomputeNeeded(schedulingMode, nodePartition, true)) {
         // recompute
         userLimitPerSchedulingMode = reComputeUserLimits(userName,
@@ -548,11 +549,11 @@ public class UsersManager implements AbstractUsersManager {
       Resource clusterResource, String nodePartition,
       SchedulingMode schedulingMode) {
 
-    Map<SchedulingMode, Resource> userLimitPerSchedulingMode = preComputedAllUserLimit
-        .get(nodePartition);
+    Map<SchedulingMode, Resource> userLimitPerSchedulingMode;
 
     try {
       writeLock.lock();
+      userLimitPerSchedulingMode = preComputedAllUserLimit.get(nodePartition);
       if (isRecomputeNeeded(schedulingMode, nodePartition, false)) {
         // recompute
         userLimitPerSchedulingMode = reComputeUserLimits(userName,