HDFS-12526. FSDirectory should use Time.monotonicNow for durations. Contributed by Bharat Viswanadham.

(cherry picked from commit 50849ec9eb9bad90586a95d2b2380ee6e8724d6b)

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

@@ -752,7 +752,7 @@ public class FSDirectory implements Closeable {
     try {
       int threads = (initThreads < 1) ? 1 : initThreads;
       LOG.info("Initializing quota with " + threads + " thread(s)");
-      long start = Time.now();
+      long start = Time.monotonicNow();
       QuotaCounts counts = new QuotaCounts.Builder().build();
       ForkJoinPool p = new ForkJoinPool(threads);
       RecursiveAction task = new InitQuotaTask(getBlockStoragePolicySuite(),
@@ -760,7 +760,7 @@ public class FSDirectory implements Closeable {
       p.execute(task);
       task.join();
       p.shutdown();
-      LOG.info("Quota initialization completed in " + (Time.now() - start) +
+      LOG.info("Quota initialization completed in " + (Time.monotonicNow() - start) +
           " milliseconds\n" + counts);
     } finally {
       writeUnlock();