From b7a66471ca9e18b6a3c6729962040bf3f54dd15a Mon Sep 17 00:00:00 2001
From: Ayush Saxena <ayushsaxena@apache.org>
Date: Thu, 22 Aug 2019 02:25:06 +0530
Subject: [PATCH] HDFS-14276. [SBN read] Reduce tailing overhead. Contributed
 by Wei-Chiu Chuang.

---
 .../hadoop/hdfs/server/namenode/ha/EditLogTailer.java     | 8 ++++++--
 .../hadoop/hdfs/server/namenode/TestNameNodeMXBean.java   | 3 +--
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ha/EditLogTailer.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ha/EditLogTailer.java
index ce2e6a5be59..56b87cd3a76 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ha/EditLogTailer.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ha/EditLogTailer.java
@@ -467,10 +467,12 @@ public class EditLogTailer {
         try {
           // There's no point in triggering a log roll if the Standby hasn't
           // read any more transactions since the last time a roll was
-          // triggered. 
+          // triggered.
+          boolean triggeredLogRoll = false;
           if (tooLongSinceLastLoad() &&
               lastRollTriggerTxId < lastLoadedTxnId) {
             triggerActiveLogRoll();
+            triggeredLogRoll = true;
           }
           /**
            * Check again in case someone calls {@link EditLogTailer#stop} while
@@ -496,7 +498,9 @@ public class EditLogTailer {
                 Time.monotonicNow() - startTime);
           }
           //Update NameDirSize Metric
-          namesystem.getFSImage().getStorage().updateNameDirSize();
+          if (triggeredLogRoll) {
+            namesystem.getFSImage().getStorage().updateNameDirSize();
+          }
         } catch (EditLogInputException elie) {
           LOG.warn("Error while reading edits from disk. Will try again.", elie);
         } catch (InterruptedException ie) {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeMXBean.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeMXBean.java
index 07a494596c4..34beb56703e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeMXBean.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeMXBean.java
@@ -666,6 +666,7 @@ public class TestNameNodeMXBean {
   public void testNNDirectorySize() throws Exception{
     Configuration conf = new Configuration();
     conf.setInt(DFSConfigKeys.DFS_HA_TAILEDITS_PERIOD_KEY, 1);
+    conf.setInt(DFSConfigKeys.DFS_HA_LOGROLL_PERIOD_KEY, 0);
     MiniDFSCluster cluster = null;
     for (int i = 0; i < 5; i++) {
       try{
@@ -695,8 +696,6 @@ public class TestNameNodeMXBean {
 
       FSNamesystem nn0 = cluster.getNamesystem(0);
       FSNamesystem nn1 = cluster.getNamesystem(1);
-      checkNNDirSize(cluster.getNameDirs(0), nn0.getNameDirSize());
-      checkNNDirSize(cluster.getNameDirs(1), nn1.getNameDirSize());
       cluster.transitionToActive(0);
       fs = cluster.getFileSystem(0);
       DFSTestUtil.createFile(fs, new Path("/file"), 0, (short) 1, 0L);