HDFS-15906. Close FSImage and FSNamesystem after formatting is complete (#2800)

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

@@ -1204,8 +1204,9 @@ public class NameNode extends ReconfigurableBase implements
     System.out.println("Formatting using clusterid: " + clusterId);
     
     FSImage fsImage = new FSImage(conf, nameDirsToFormat, editDirsToFormat);
+    FSNamesystem fsn = null;
     try {
-      FSNamesystem fsn = new FSNamesystem(conf, fsImage);
+      fsn = new FSNamesystem(conf, fsImage);
       fsImage.getEditLog().initJournalsForWrite();
 
       // Abort NameNode format if reformat is disabled and if
@@ -1230,8 +1231,14 @@ public class NameNode extends ReconfigurableBase implements
       fsImage.format(fsn, clusterId, force);
     } catch (IOException ioe) {
       LOG.warn("Encountered exception during format: ", ioe);
-      fsImage.close();
       throw ioe;
+    } finally {
+      if (fsImage != null) {
+        fsImage.close();
+      }
+      if (fsn != null) {
+        fsn.close();
+      }
     }
     return false;
   }