diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/TaskPage.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/TaskPage.java
index 8aa8bb6d258..e293fd22201 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/TaskPage.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/TaskPage.java
@@ -18,7 +18,6 @@
 
 package org.apache.hadoop.mapreduce.v2.app.webapp;
 
-import static org.apache.hadoop.yarn.util.StringHelper.percent;
 import static org.apache.hadoop.yarn.webapp.view.JQueryUI.ACCORDION;
 import static org.apache.hadoop.yarn.webapp.view.JQueryUI.DATATABLES;
 import static org.apache.hadoop.yarn.webapp.view.JQueryUI.DATATABLES_ID;
@@ -31,6 +30,7 @@ import org.apache.commons.lang.StringEscapeUtils;
 import org.apache.hadoop.mapreduce.v2.app.job.TaskAttempt;
 import org.apache.hadoop.mapreduce.v2.app.webapp.dao.TaskAttemptInfo;
 import org.apache.hadoop.mapreduce.v2.util.MRWebAppUtil;
+import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.yarn.webapp.SubView;
 import org.apache.hadoop.yarn.webapp.hamlet.Hamlet;
 import org.apache.hadoop.yarn.webapp.hamlet.Hamlet.TABLE;
@@ -77,7 +77,7 @@ public class TaskPage extends AppView {
 
       for (TaskAttempt attempt : getTaskAttempts()) {
         TaskAttemptInfo ta = new TaskAttemptInfo(attempt, true);
-        String progress = percent(ta.getProgress() / 100);
+        String progress = StringUtils.formatPercent(ta.getProgress() / 100, 2);
 
         String nodeHttpAddr = ta.getNode();
         String diag = ta.getNote() == null ? "" : ta.getNote();
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/TasksBlock.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/TasksBlock.java
index 64aae59cab4..7c1aa49b22f 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/TasksBlock.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/TasksBlock.java
@@ -21,7 +21,6 @@ package org.apache.hadoop.mapreduce.v2.app.webapp;
 import static org.apache.hadoop.mapreduce.v2.app.webapp.AMParams.TASK_STATE;
 import static org.apache.hadoop.mapreduce.v2.app.webapp.AMParams.TASK_TYPE;
 import static org.apache.hadoop.yarn.util.StringHelper.join;
-import static org.apache.hadoop.yarn.util.StringHelper.percent;
 import static org.apache.hadoop.yarn.webapp.view.JQueryUI.C_PROGRESSBAR;
 import static org.apache.hadoop.yarn.webapp.view.JQueryUI.C_PROGRESSBAR_VALUE;
 
@@ -30,6 +29,7 @@ import org.apache.hadoop.mapreduce.v2.api.records.TaskType;
 import org.apache.hadoop.mapreduce.v2.app.job.Task;
 import org.apache.hadoop.mapreduce.v2.app.webapp.dao.TaskInfo;
 import org.apache.hadoop.mapreduce.v2.util.MRApps;
+import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.yarn.webapp.hamlet.Hamlet;
 import org.apache.hadoop.yarn.webapp.hamlet.Hamlet.TABLE;
 import org.apache.hadoop.yarn.webapp.hamlet.Hamlet.TBODY;
@@ -94,7 +94,7 @@ public class TasksBlock extends HtmlBlock {
 
       TaskInfo info = new TaskInfo(task);
       String tid = info.getId();
-      String pct = percent(info.getProgress() / 100);
+      String pct = StringUtils.formatPercent(info.getProgress() / 100, 2);
       tasksTableData.append("[\"<a href='").append(url("task", tid))
       .append("'>").append(tid).append("</a>\",\"")
       //Progress bar
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/dao/JobInfo.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/dao/JobInfo.java
index 50ebd16aa60..d823cad4b99 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/dao/JobInfo.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/dao/JobInfo.java
@@ -17,8 +17,6 @@
  */
 package org.apache.hadoop.mapreduce.v2.app.webapp.dao;
 
-import static org.apache.hadoop.yarn.util.StringHelper.percent;
-
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
@@ -39,6 +37,7 @@ import org.apache.hadoop.mapreduce.v2.app.job.TaskAttempt;
 import org.apache.hadoop.mapreduce.v2.util.MRApps;
 import org.apache.hadoop.mapreduce.v2.util.MRApps.TaskAttemptStateUI;
 import org.apache.hadoop.security.authorize.AccessControlList;
+import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.yarn.util.Times;
 
 @XmlRootElement(name = "job")
@@ -102,11 +101,13 @@ public class JobInfo {
     this.mapsTotal = job.getTotalMaps();
     this.mapsCompleted = job.getCompletedMaps();
     this.mapProgress = report.getMapProgress() * 100;
-    this.mapProgressPercent = percent(report.getMapProgress());
+    this.mapProgressPercent =
+        StringUtils.formatPercent(report.getMapProgress(), 2);
     this.reducesTotal = job.getTotalReduces();
     this.reducesCompleted = job.getCompletedReduces();
     this.reduceProgress = report.getReduceProgress() * 100;
-    this.reduceProgressPercent = percent(report.getReduceProgress());
+    this.reduceProgressPercent =
+        StringUtils.formatPercent(report.getReduceProgress(), 2);
 
     this.acls = new ArrayList<ConfEntryInfo>();
     if (hasAccess) {
diff --git a/hadoop-yarn-project/CHANGES.txt b/hadoop-yarn-project/CHANGES.txt
index a6b7f1747fd..6dac3c8ae00 100644
--- a/hadoop-yarn-project/CHANGES.txt
+++ b/hadoop-yarn-project/CHANGES.txt
@@ -310,6 +310,9 @@ Release 2.8.0 - UNRELEASED
     YARN-3552. RM Web UI shows -1 running containers for completed apps
     (Rohith via jlowe)
 
+    YARN-2123. Progress bars in Web UI always at 100% due to non-US locale.
+    (Akira AJISAKA via xgong)
+
 Release 2.7.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/util/StringHelper.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/util/StringHelper.java
index 3343a1713e6..0240fbcd59f 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/util/StringHelper.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/util/StringHelper.java
@@ -174,9 +174,4 @@ public final class StringHelper {
     }
     sb.append(part);
   }
-  
-  public static String percent(double value) {
-    return String.format("%.2f", value * 100);
-  }
-
 }
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common/src/main/java/org/apache/hadoop/yarn/server/webapp/AppsBlock.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common/src/main/java/org/apache/hadoop/yarn/server/webapp/AppsBlock.java
index 93248ea589c..5df70c47733 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common/src/main/java/org/apache/hadoop/yarn/server/webapp/AppsBlock.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common/src/main/java/org/apache/hadoop/yarn/server/webapp/AppsBlock.java
@@ -32,6 +32,7 @@ import org.apache.commons.lang.StringEscapeUtils;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.security.UserGroupInformation;
+import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.yarn.api.ApplicationBaseProtocol;
 import org.apache.hadoop.yarn.api.protocolrecords.GetApplicationsRequest;
 import org.apache.hadoop.yarn.api.records.ApplicationReport;
@@ -123,7 +124,7 @@ public class AppsBlock extends HtmlBlock {
         continue;
       }
       AppInfo app = new AppInfo(appReport);
-      String percent = String.format("%.1f", app.getProgress());
+      String percent = StringUtils.format("%.1f", app.getProgress());
       appsTableData
         .append("[\"<a href='")
         .append(url("app", app.getAppId()))
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/resource/ResourceWeights.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/resource/ResourceWeights.java
index d6e9e45b838..4c62318e6f4 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/resource/ResourceWeights.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/resource/ResourceWeights.java
@@ -63,7 +63,7 @@ public class ResourceWeights {
       }
       ResourceType resourceType = ResourceType.values()[i];
       sb.append(StringUtils.toLowerCase(resourceType.name()));
-      sb.append(String.format(" weight=%.1f", getWeight(resourceType)));
+      sb.append(StringUtils.format(" weight=%.1f", getWeight(resourceType)));
     }
     sb.append(">");
     return sb.toString();
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/CapacitySchedulerPage.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/CapacitySchedulerPage.java
index fa22a0d8309..4381a341ff5 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/CapacitySchedulerPage.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/CapacitySchedulerPage.java
@@ -94,7 +94,8 @@ class CapacitySchedulerPage extends RmView {
           _("Configured Capacity:", percent(lqinfo.getCapacity() / 100)).
           _("Configured Max Capacity:", percent(lqinfo.getMaxCapacity() / 100)).
           _("Configured Minimum User Limit Percent:", Integer.toString(lqinfo.getUserLimit()) + "%").
-          _("Configured User Limit Factor:", String.format("%.1f", lqinfo.getUserLimitFactor())).
+          _("Configured User Limit Factor:", StringUtils.format(
+              "%.1f", lqinfo.getUserLimitFactor())).
           _("Accessible Node Labels:", StringUtils.join(",", lqinfo.getNodeLabels())).
           _("Ordering Policy: ", lqinfo.getOrderingPolicyInfo()).
           _("Preemption:", lqinfo.getPreemptionDisabled() ? "disabled" : "enabled");
@@ -432,14 +433,14 @@ class CapacitySchedulerPage extends RmView {
   }
 
   static String percent(float f) {
-    return String.format("%.1f%%", f * 100);
+    return StringUtils.formatPercent(f, 1);
   }
 
   static String width(float f) {
-    return String.format("width:%.1f%%", f * 100);
+    return StringUtils.format("width:%.1f%%", f * 100);
   }
 
   static String left(float f) {
-    return String.format("left:%.1f%%", f * 100);
+    return StringUtils.format("left:%.1f%%", f * 100);
   }
 }
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/DefaultSchedulerPage.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/DefaultSchedulerPage.java
index 1c8828cf7e0..36d83094719 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/DefaultSchedulerPage.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/DefaultSchedulerPage.java
@@ -20,6 +20,7 @@ package org.apache.hadoop.yarn.server.resourcemanager.webapp;
 
 import static org.apache.hadoop.yarn.util.StringHelper.join;
 
+import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.yarn.server.resourcemanager.ResourceManager;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.fifo.FifoScheduler;
 import org.apache.hadoop.yarn.server.resourcemanager.webapp.dao.FifoSchedulerInfo;
@@ -149,14 +150,14 @@ class DefaultSchedulerPage extends RmView {
   }
 
   static String percent(float f) {
-    return String.format("%.1f%%", f * 100);
+    return StringUtils.formatPercent(f, 1);
   }
 
   static String width(float f) {
-    return String.format("width:%.1f%%", f * 100);
+    return StringUtils.format("width:%.1f%%", f * 100);
   }
 
   static String left(float f) {
-    return String.format("left:%.1f%%", f * 100);
+    return StringUtils.format("left:%.1f%%", f * 100);
   }
 }
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/FairSchedulerAppsBlock.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/FairSchedulerAppsBlock.java
index 8f8ece06b9c..80099d05a69 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/FairSchedulerAppsBlock.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/FairSchedulerAppsBlock.java
@@ -31,6 +31,7 @@ import java.util.concurrent.ConcurrentMap;
 
 import org.apache.commons.lang.StringEscapeUtils;
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.yarn.api.records.ApplicationAttemptId;
 import org.apache.hadoop.yarn.api.records.ApplicationId;
 import org.apache.hadoop.yarn.api.records.YarnApplicationState;
@@ -110,7 +111,7 @@ public class FairSchedulerAppsBlock extends HtmlBlock {
         continue;
       }
       AppInfo appInfo = new AppInfo(rm, app, true, WebAppUtils.getHttpSchemePrefix(conf));
-      String percent = String.format("%.1f", appInfo.getProgress());
+      String percent = StringUtils.format("%.1f", appInfo.getProgress());
       ApplicationAttemptId attemptId = app.getCurrentAppAttempt().getAppAttemptId();
       int fairShare = fsinfo.getAppFairShare(attemptId);
       if (fairShare == FairSchedulerInfo.INVALID_FAIR_SHARE) {
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/FairSchedulerPage.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/FairSchedulerPage.java
index 76d7e6fd318..d87fb5c25c2 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/FairSchedulerPage.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/FairSchedulerPage.java
@@ -22,6 +22,7 @@ import static org.apache.hadoop.yarn.util.StringHelper.join;
 
 import java.util.Collection;
 
+import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.yarn.server.resourcemanager.ResourceManager;
 import org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FairScheduler;
 import org.apache.hadoop.yarn.server.resourcemanager.webapp.dao.FairSchedulerInfo;
@@ -241,14 +242,14 @@ public class FairSchedulerPage extends RmView {
   }
 
   static String percent(float f) {
-    return String.format("%.1f%%", f * 100);
+    return StringUtils.formatPercent(f, 1);
   }
 
   static String width(float f) {
-    return String.format("width:%.1f%%", f * 100);
+    return StringUtils.format("width:%.1f%%", f * 100);
   }
 
   static String left(float f) {
-    return String.format("left:%.1f%%", f * 100);
+    return StringUtils.format("left:%.1f%%", f * 100);
   }
 }
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/RMAppsBlock.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/RMAppsBlock.java
index 30541501c2e..1d97bef5eab 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/RMAppsBlock.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/webapp/RMAppsBlock.java
@@ -25,6 +25,7 @@ import static org.apache.hadoop.yarn.webapp.view.JQueryUI.C_PROGRESSBAR_VALUE;
 import java.util.Set;
 
 import org.apache.commons.lang.StringEscapeUtils;
+import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.yarn.api.ApplicationBaseProtocol;
 import org.apache.hadoop.yarn.api.records.ApplicationReport;
 import org.apache.hadoop.yarn.api.records.YarnApplicationState;
@@ -82,7 +83,7 @@ public class RMAppsBlock extends AppsBlock {
       if (nodes != null) {
         blacklistedNodesCount = String.valueOf(nodes.size());
       }
-      String percent = String.format("%.1f", app.getProgress());
+      String percent = StringUtils.format("%.1f", app.getProgress());
       appsTableData
         .append("[\"<a href='")
         .append(url("app", app.getAppId()))