From 9274626a115802217346f845e968866cd0e4b2d8 Mon Sep 17 00:00:00 2001
From: Sanford Ryza <sandy@apache.org>
Date: Fri, 11 Apr 2014 23:24:40 +0000
Subject: [PATCH] YARN-1923. Make Fair Scheduler resource ratio calculations
 terminate faster (Anubhav Dhoot via Sandy Ryza)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1586796 13f79535-47bb-0310-9956-ffa450edef68
---
 hadoop-yarn-project/CHANGES.txt                           | 3 +++
 .../scheduler/fair/policies/ComputeFairShares.java        | 8 ++++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/hadoop-yarn-project/CHANGES.txt b/hadoop-yarn-project/CHANGES.txt
index e410cfcf1e..06fffcd6dd 100644
--- a/hadoop-yarn-project/CHANGES.txt
+++ b/hadoop-yarn-project/CHANGES.txt
@@ -50,6 +50,9 @@ Release 2.5.0 - UNRELEASED
     YARN-1889. In Fair Scheduler, avoid creating objects on each call to
     AppSchedulable comparator (Hong Zhiguo via Sandy Ryza)
 
+    YARN-1923. Make Fair Scheduler resource ratio calculations terminate faster
+    (Anubhav Dhoot via Sandy Ryza)
+
   OPTIMIZATIONS
 
   BUG FIXES 
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/policies/ComputeFairShares.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/policies/ComputeFairShares.java
index c8fd450aa0..77dad49326 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/policies/ComputeFairShares.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/policies/ComputeFairShares.java
@@ -107,8 +107,12 @@ public static void computeShares(
     double right = rMax;
     for (int i = 0; i < COMPUTE_FAIR_SHARES_ITERATIONS; i++) {
       double mid = (left + right) / 2.0;
-      if (resourceUsedWithWeightToResourceRatio(mid, schedulables, type) <
-          totalResource) {
+      int plannedResourceUsed = resourceUsedWithWeightToResourceRatio(
+          mid, schedulables, type);
+      if (plannedResourceUsed == totalResource) {
+        right = mid;
+        break;
+      } else if (plannedResourceUsed < totalResource) {
         left = mid;
       } else {
         right = mid;