From 87590090c887829e874a7132be9cf8de061437d6 Mon Sep 17 00:00:00 2001
From: Yufei Gu <yufei@apache.org>
Date: Thu, 25 May 2017 14:22:13 -0700
Subject: [PATCH] YARN-6582. FSAppAttempt demand can be updated atomically in
 updateDemand(). (Karthik Kambatla via Yufei Gu)

---
 .../scheduler/fair/FSAppAttempt.java          | 23 ++++++++-----------
 1 file changed, 10 insertions(+), 13 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/fair/FSAppAttempt.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FSAppAttempt.java
index 4f7e16483a..a5772badf2 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FSAppAttempt.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/fair/FSAppAttempt.java
@@ -1286,24 +1286,21 @@ public void setFairShare(Resource fairShare) {
 
   @Override
   public void updateDemand() {
-    demand = Resources.createResource(0);
     // Demand is current consumption plus outstanding requests
-    Resources.addTo(demand, getCurrentConsumption());
+    Resource tmpDemand = Resources.clone(getCurrentConsumption());
 
     // Add up outstanding resource requests
-    try {
-      writeLock.lock();
-      for (SchedulerRequestKey k : getSchedulerKeys()) {
-        PendingAsk pendingAsk = getPendingAsk(k, ResourceRequest.ANY);
-        if (pendingAsk.getCount() > 0) {
-          Resources.multiplyAndAddTo(demand,
-              pendingAsk.getPerAllocationResource(),
-              pendingAsk.getCount());
-        }
+    for (SchedulerRequestKey k : getSchedulerKeys()) {
+      PendingAsk pendingAsk = getPendingAsk(k, ResourceRequest.ANY);
+      if (pendingAsk.getCount() > 0) {
+        Resources.multiplyAndAddTo(tmpDemand,
+            pendingAsk.getPerAllocationResource(),
+            pendingAsk.getCount());
       }
-    } finally {
-      writeLock.unlock();
     }
+
+    // Update demand
+    demand = tmpDemand;
   }
 
   @Override