YARN-3019. Make work-preserving-recovery the default mechanism for RM recovery. (Contributed by Jian He)

(cherry picked from commit f92e5038000a012229c304bc6e5281411eff2883)

hadoop-yarn-project/CHANGES.txt

@@ -149,6 +149,9 @@ Release 2.7.0 - UNRELEASED
     YARN-2643. Don't create a new DominantResourceCalculator on every
     FairScheduler.allocate call. (kasha via rkanter)
 
+    YARN-3019. Make work-preserving-recovery the default mechanism for RM 
+    recovery. (Jian He via junping_du)
+
   OPTIMIZATIONS
 
   BUG FIXES

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/conf/YarnConfiguration.java

@@ -378,7 +378,7 @@ public class YarnConfiguration extends Configuration {
       + "work-preserving-recovery.enabled";
   @Private
   public static final boolean DEFAULT_RM_WORK_PRESERVING_RECOVERY_ENABLED =
-      false;
+      true;
 
   public static final String RM_WORK_PRESERVING_RECOVERY_SCHEDULING_WAIT_MS =
       RM_PREFIX + "work-preserving-recovery.scheduling-wait-ms";

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/resources/yarn-default.xml

@@ -271,7 +271,7 @@
     to YARN for experimenting the feature.
     </description>
     <name>yarn.resourcemanager.work-preserving-recovery.enabled</name>
-    <value>false</value>
+    <value>true</value>
   </property>
 
   <property>