HDFS-6545. Finalizing rolling upgrade can make NN unavailable for a long duration. Contributed by Kihwal Lee.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1603239 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -449,6 +449,9 @@ Release 2.5.0 - UNRELEASED
 
     HDFS-6528. Add XAttrs to TestOfflineImageViewer. (Stephen Chu via wang)
 
+    HDFS-6545. Finalizing rolling upgrade can make NN unavailable for a long
+    duration. (kihwal)
+
   OPTIMIZATIONS
 
     HDFS-6214. Webhdfs has poor throughput for files >2GB (daryn)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java

@@ -7639,14 +7639,20 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
 
       returnInfo = finalizeRollingUpgradeInternal(now());
       getEditLog().logFinalizeRollingUpgrade(returnInfo.getFinalizeTime());
-      getFSImage().saveNamespace(this);
+      if (haEnabled) {
+        // roll the edit log to make sure the standby NameNode can tail
+        getFSImage().rollEditLog();
+      }
       getFSImage().renameCheckpoint(NameNodeFile.IMAGE_ROLLBACK,
           NameNodeFile.IMAGE);
     } finally {
       writeUnlock();
     }
 
-    // getEditLog().logSync() is not needed since it does saveNamespace 
+    if (!haEnabled) {
+      // Sync not needed for ha since the edit was rolled after logging.
+      getEditLog().logSync();
+    }
 
     if (auditLog.isInfoEnabled() && isExternalInvocation()) {
       logAuditEvent(true, "finalizeRollingUpgrade", null, null, null);