From f65dc6ee952d63b80766e1a3a298558443678ae9 Mon Sep 17 00:00:00 2001
From: Brahma Reddy Battula <brahma@apache.org>
Date: Fri, 21 Jul 2017 21:13:20 +0800
Subject: [PATCH] HDFS-12177. NameNode exits due to setting
 BlockPlacementPolicy loglevel to Debug. Contributed by Jiandan Yang.

---
 .../server/blockmanagement/BlockPlacementPolicyDefault.java   | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockPlacementPolicyDefault.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockPlacementPolicyDefault.java
index 91ba598ecaf..d688ee1c7b0 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockPlacementPolicyDefault.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockPlacementPolicyDefault.java
@@ -718,7 +718,7 @@ public class BlockPlacementPolicyDefault extends BlockPlacementPolicy {
       }
       Preconditions.checkState(excludedNodes.add(chosenNode), "chosenNode "
           + chosenNode + " is already in excludedNodes " + excludedNodes);
-      if (LOG.isDebugEnabled()) {
+      if (LOG.isDebugEnabled() && builder != null) {
         builder.append("\nNode ").append(NodeBase.getPath(chosenNode))
             .append(" [");
       }
@@ -747,7 +747,7 @@ public class BlockPlacementPolicyDefault extends BlockPlacementPolicy {
           }
         }
 
-        if (LOG.isDebugEnabled()) {
+        if (LOG.isDebugEnabled() && builder != null) {
           builder.append("\n]");
         }