YARN-4250. NPE in AppSchedulingInfo#isRequestLabelChanged. (Brahma Reddy Battula via rohithsharmaks)

hadoop-yarn-project/CHANGES.txt

@@ -940,6 +940,8 @@ Release 2.8.0 - UNRELEASED
     YARN-4255. container-executor does not clean up docker operation command files.
     (Sidharta Seethana via vvasudev)
 
+    YARN-4250. NPE in AppSchedulingInfo#isRequestLabelChanged. (Brahma Reddy Battula via rohithsharmaks)
+
 Release 2.7.2 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/AppSchedulingInfo.java

@@ -417,7 +417,15 @@ public class AppSchedulingInfo {
       ResourceRequest requestTwo) {
     String requestOneLabelExp = requestOne.getNodeLabelExpression();
     String requestTwoLabelExp = requestTwo.getNodeLabelExpression();
-    return (!(requestOneLabelExp.equals(requestTwoLabelExp)));
+    // First request label expression can be null and second request
+    // is not null then we have to consider it as changed.
+    if ((null == requestOneLabelExp) && (null != requestTwoLabelExp)) {
+      return true;
+    }
+    // If the label is not matching between both request when
+    // requestOneLabelExp is not null.
+    return ((null != requestOneLabelExp) && !(requestOneLabelExp
+        .equals(requestTwoLabelExp)));
   }
 
   /**