From 2044967e7581f00c3f6378860426a69078faf694 Mon Sep 17 00:00:00 2001
From: Suma Shivaprasad <sumasai@apache.org>
Date: Tue, 5 Feb 2019 09:39:38 -0800
Subject: [PATCH] YARN-9246 NPE when executing a command yarn node -status or
 -states without additional arguments. Contributed by Masahiro Tanaka

---
 .../java/org/apache/hadoop/yarn/client/cli/YarnCLI.java     | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-client/src/main/java/org/apache/hadoop/yarn/client/cli/YarnCLI.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-client/src/main/java/org/apache/hadoop/yarn/client/cli/YarnCLI.java
index 0747b63773..c1e02d5fd1 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-client/src/main/java/org/apache/hadoop/yarn/client/cli/YarnCLI.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-client/src/main/java/org/apache/hadoop/yarn/client/cli/YarnCLI.java
@@ -72,6 +72,10 @@ public void setClient(YarnClient client) {
   }
 
   public void stop() {
-    this.client.stop();
+    // this.client may be null when it is called before
+    // invoking `createAndStartYarnClient`
+    if (this.client != null) {
+      this.client.stop();
+    }
   }
 }
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