From a65c3ea91cad7e8b453976bab2165ea4a3c6daf9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?M=C3=A1rton=20Elek?= <elek@apache.org>
Date: Sat, 15 Sep 2018 13:35:00 +0200
Subject: [PATCH] HDDS-449. Add a NULL check to protect
 DeadNodeHandler#onMessage. Contributed by LiXin Ge.

---
 .../org/apache/hadoop/hdds/scm/node/DeadNodeHandler.java     | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/node/DeadNodeHandler.java b/hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/node/DeadNodeHandler.java
index d694a103a69..7fda67d9af2 100644
--- a/hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/node/DeadNodeHandler.java
+++ b/hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/node/DeadNodeHandler.java
@@ -57,6 +57,11 @@ public class DeadNodeHandler implements EventHandler<DatanodeDetails> {
       EventPublisher publisher) {
     Set<ContainerID> containers =
         node2ContainerMap.getContainers(datanodeDetails.getUuid());
+    if (containers == null) {
+      LOG.info("There's no containers in dead datanode {}, no replica will be"
+          + " removed from the in-memory state.", datanodeDetails.getUuid());
+      return;
+    }
     LOG.info(
         "Datanode {}  is dead. Removing replications from the in-memory state.",
         datanodeDetails.getUuid());