diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index ea1a78a1f0d..59b3f75541b 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -2510,6 +2510,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-9570. Minor typos, grammar, and case sensitivity cleanup in
     HdfsPermissionsGuide.md's (Travis Campbell via aw)
 
+    HDFS-9515. NPE when MiniDFSCluster#shutdown is invoked on uninitialized
+    reference. (Wei-Chiu Chuang via Arpit Agarwal)
+
 Release 2.7.3 - UNRELEASED
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/contrib/bkjournal/src/test/java/org/apache/hadoop/contrib/bkjournal/TestBootstrapStandbyWithBKJM.java b/hadoop-hdfs-project/hadoop-hdfs/src/contrib/bkjournal/src/test/java/org/apache/hadoop/contrib/bkjournal/TestBootstrapStandbyWithBKJM.java
index 18dedc83733..ef7f7086dab 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/contrib/bkjournal/src/test/java/org/apache/hadoop/contrib/bkjournal/TestBootstrapStandbyWithBKJM.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/contrib/bkjournal/src/test/java/org/apache/hadoop/contrib/bkjournal/TestBootstrapStandbyWithBKJM.java
@@ -63,6 +63,7 @@ public static void teardownBookkeeper() throws Exception {
   public void teardown() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/TestRefreshCallQueue.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/TestRefreshCallQueue.java
index f66f9b6105f..1be2752fe0a 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/TestRefreshCallQueue.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/TestRefreshCallQueue.java
@@ -86,6 +86,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if(cluster!=null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestAclCLI.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestAclCLI.java
index a6f8651b355..061d328a52c 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestAclCLI.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestAclCLI.java
@@ -49,9 +49,11 @@ public void tearDown() throws Exception {
     super.tearDown();
     if (fs != null) {
       fs.close();
+      fs = null;
     }
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestCacheAdminCLI.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestCacheAdminCLI.java
index ddb11b6cf0f..28321cb6131 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestCacheAdminCLI.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestCacheAdminCLI.java
@@ -76,9 +76,11 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (fs != null) {
       fs.close();
+      fs = null;
     }
     if (dfsCluster != null) {
       dfsCluster.shutdown();
+      dfsCluster = null;
     }
     Thread.sleep(2000);
     super.tearDown();
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestCryptoAdminCLI.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestCryptoAdminCLI.java
index 44e662fac97..bd5349d82d6 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestCryptoAdminCLI.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestCryptoAdminCLI.java
@@ -86,9 +86,11 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (fs != null) {
       fs.close();
+      fs = null;
     }
     if (dfsCluster != null) {
       dfsCluster.shutdown();
+      dfsCluster = null;
     }
     Thread.sleep(2000);
     super.tearDown();
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestDeleteCLI.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestDeleteCLI.java
index 04328f52800..4c27f79e16a 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestDeleteCLI.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestDeleteCLI.java
@@ -58,9 +58,11 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (fs != null) {
       fs.close();
+      fs = null;
     }
     if (dfsCluster != null) {
       dfsCluster.shutdown();
+      dfsCluster = null;
     }
     Thread.sleep(2000);
     super.tearDown();
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestErasureCodingCLI.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestErasureCodingCLI.java
index 29ec98ea55a..664c0448ecd 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestErasureCodingCLI.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestErasureCodingCLI.java
@@ -61,9 +61,11 @@ protected String getTestFile() {
   public void tearDown() throws Exception {
     if (fs != null) {
       fs.close();
+      fs = null;
     }
     if (dfsCluster != null) {
       dfsCluster.shutdown();
+      dfsCluster = null;
     }
     Thread.sleep(2000);
     super.tearDown();
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestHDFSCLI.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestHDFSCLI.java
index 36307262874..e0e78941c73 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestHDFSCLI.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestHDFSCLI.java
@@ -77,9 +77,11 @@ protected String getTestFile() {
   public void tearDown() throws Exception {
     if (fs != null) {
       fs.close();
+      fs = null;
     }
     if (dfsCluster != null) {
       dfsCluster.shutdown();
+      dfsCluster = null;
     }
     Thread.sleep(2000);
     super.tearDown();
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestXAttrCLI.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestXAttrCLI.java
index 45c7909c17c..d83baf3a971 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestXAttrCLI.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/cli/TestXAttrCLI.java
@@ -67,9 +67,11 @@ protected String getTestFile() {
   public void tearDown() throws Exception {
     if (fs != null) {
       fs.close();
+      fs = null;
     }
     if (dfsCluster != null) {
       dfsCluster.shutdown();
+      dfsCluster = null;
     }
     Thread.sleep(2000);
     super.tearDown();
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestFcHdfsCreateMkdir.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestFcHdfsCreateMkdir.java
index 40dbc4e88c9..0d3e6ff8379 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestFcHdfsCreateMkdir.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestFcHdfsCreateMkdir.java
@@ -58,7 +58,9 @@ public static void clusterSetupAtBegining()
       
   @AfterClass
   public static void ClusterShutdownAtEnd() throws Exception {
-    cluster.shutdown();   
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
   
   @Override
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestFcHdfsPermission.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestFcHdfsPermission.java
index 9f0b23cedfe..10ae1ef4b1e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestFcHdfsPermission.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestFcHdfsPermission.java
@@ -65,7 +65,9 @@ public static void clusterSetupAtBegining()
       
   @AfterClass
   public static void ClusterShutdownAtEnd() throws Exception {
-    cluster.shutdown();   
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
   
   @Override
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestFcHdfsSetUMask.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestFcHdfsSetUMask.java
index 34fbe7f4f1d..09163472ca0 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestFcHdfsSetUMask.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestFcHdfsSetUMask.java
@@ -96,7 +96,9 @@ public static void clusterSetupAtBegining()
 
   @AfterClass
   public static void ClusterShutdownAtEnd() throws Exception {
-    cluster.shutdown();   
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
   
   {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestSymlinkHdfs.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestSymlinkHdfs.java
index 6d7ef5548b9..042431e2a6c 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestSymlinkHdfs.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/TestSymlinkHdfs.java
@@ -96,7 +96,9 @@ public static void beforeClassSetup() throws Exception {
 
   @AfterClass
   public static void afterClassTeardown() throws Exception {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
 
   @Test(timeout=10000)
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/contract/hdfs/HDFSContract.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/contract/hdfs/HDFSContract.java
index 258703af5b7..74b9a35adfc 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/contract/hdfs/HDFSContract.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/contract/hdfs/HDFSContract.java
@@ -62,6 +62,7 @@ public static void createCluster() throws IOException {
   public static void destroyCluster() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/shell/TestHdfsTextCommand.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/shell/TestHdfsTextCommand.java
index 76c32bfbaa9..23de6585296 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/shell/TestHdfsTextCommand.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/shell/TestHdfsTextCommand.java
@@ -60,9 +60,11 @@ public void setUp() throws IOException{
     public void tearDown() throws IOException{
     if(fs != null){
       fs.close();
+      fs = null;
     }
     if(cluster != null){
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFileSystemHdfs.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFileSystemHdfs.java
index 24dd7a34d25..92213172784 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFileSystemHdfs.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFileSystemHdfs.java
@@ -88,7 +88,9 @@ public static void clusterSetupAtBegining() throws IOException,
       
   @AfterClass
   public static void ClusterShutdownAtEnd() throws Exception {
-    cluster.shutdown();   
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
 
   @Override
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFileSystemWithAcls.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFileSystemWithAcls.java
index 68dd7f2239f..a3e56570863 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFileSystemWithAcls.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFileSystemWithAcls.java
@@ -76,7 +76,9 @@ public static void clusterSetupAtBeginning() throws IOException {
 
   @AfterClass
   public static void ClusterShutdownAtEnd() throws Exception {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
 
   @Before
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFileSystemWithXAttrs.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFileSystemWithXAttrs.java
index 227548de99d..b487188c4e1 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFileSystemWithXAttrs.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFileSystemWithXAttrs.java
@@ -71,7 +71,9 @@ public static void clusterSetupAtBeginning() throws IOException {
 
   @AfterClass
   public static void ClusterShutdownAtEnd() throws Exception {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
 
   @Before
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFsAtHdfsRoot.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFsAtHdfsRoot.java
index 9fb3a5b5cc7..88664651883 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFsAtHdfsRoot.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFsAtHdfsRoot.java
@@ -64,7 +64,9 @@ public static void clusterSetupAtBegining() throws IOException,
       
   @AfterClass
   public static void ClusterShutdownAtEnd() throws Exception {
-    cluster.shutdown();   
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
 
   @Override
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFsHdfs.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFsHdfs.java
index 96a395cfa34..fda667251b8 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFsHdfs.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFsHdfs.java
@@ -64,7 +64,9 @@ public static void clusterSetupAtBegining() throws IOException,
       
   @AfterClass
   public static void ClusterShutdownAtEnd() throws Exception {
-    cluster.shutdown();   
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
 
   @Override
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFsWithAcls.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFsWithAcls.java
index 70918e9d2b5..e7e664857c8 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFsWithAcls.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFsWithAcls.java
@@ -76,7 +76,9 @@ public static void clusterSetupAtBeginning() throws IOException {
 
   @AfterClass
   public static void ClusterShutdownAtEnd() throws Exception {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
 
   @Before
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFsWithXAttrs.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFsWithXAttrs.java
index 431f851406b..9a4223a86fe 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFsWithXAttrs.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFsWithXAttrs.java
@@ -70,7 +70,9 @@ public static void clusterSetupAtBeginning() throws IOException {
 
   @AfterClass
   public static void ClusterShutdownAtEnd() throws Exception {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
 
   @Before
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/FileAppendTest4.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/FileAppendTest4.java
index 6b9c138f66b..9e7b598b9bd 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/FileAppendTest4.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/FileAppendTest4.java
@@ -68,7 +68,9 @@ public static void startUp () throws IOException {
 
   @AfterClass
   public static void tearDown() {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
   
   /**
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestAbandonBlock.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestAbandonBlock.java
index 22a471e759b..301f6a7d730 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestAbandonBlock.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestAbandonBlock.java
@@ -56,8 +56,14 @@ public void setUp() throws Exception {
 
   @After
   public void tearDown() throws Exception {
-    fs.close();
-    cluster.shutdown();
+    if (fs != null) {
+      fs.close();
+      fs = null;
+    }
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
 
   @Test
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestBlocksScheduledCounter.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestBlocksScheduledCounter.java
index a66cd1d8b58..b9432197489 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestBlocksScheduledCounter.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestBlocksScheduledCounter.java
@@ -43,9 +43,11 @@ public class TestBlocksScheduledCounter {
   public void tearDown() throws IOException {
     if (fs != null) {
       fs.close();
+      fs = null;
     }
     if(cluster!=null){
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestClientReportBadBlock.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestClientReportBadBlock.java
index 6b2eb3c2e03..ce2e79b73e4 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestClientReportBadBlock.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestClientReportBadBlock.java
@@ -82,8 +82,14 @@ public void startUpCluster() throws IOException {
 
   @After
   public void shutDownCluster() throws IOException {
-    dfs.close();
-    cluster.shutdown();
+    if (dfs != null) {
+      dfs.close();
+      dfs = null;
+    }
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
 
   /*
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSClientExcludedNodes.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSClientExcludedNodes.java
index c253f475df5..59cc1540716 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSClientExcludedNodes.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSClientExcludedNodes.java
@@ -54,6 +54,7 @@ public void setUp() {
   public void tearDown() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSClientFailover.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSClientFailover.java
index 60ffe30a74d..75635193eb2 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSClientFailover.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSClientFailover.java
@@ -88,6 +88,7 @@ public void setUpCluster() throws IOException {
   public void tearDownCluster() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSClientSocketSize.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSClientSocketSize.java
index aaeaa0181b9..23765763d36 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSClientSocketSize.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSClientSocketSize.java
@@ -82,6 +82,7 @@ public void tearDown() throws Exception {
     if (cluster != null) {
       LOG.info("Shutting down MiniDFSCluster.");
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSFinalize.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSFinalize.java
index 39d3c96f6d6..d0df9fecf59 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSFinalize.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSFinalize.java
@@ -188,7 +188,10 @@ public void testFinalize() throws Exception {
   @After
   public void tearDown() throws Exception {
     LOG.info("Shutting down MiniDFSCluster");
-    if (cluster != null) cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
   
   public static void main(String[] args) throws Exception {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSOutputStream.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSOutputStream.java
index 821d259100f..a404ac8174f 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSOutputStream.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSOutputStream.java
@@ -150,6 +150,8 @@ public void testCongestionBackoff() throws IOException {
 
   @AfterClass
   public static void tearDown() {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
 }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSPermission.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSPermission.java
index 80b2eb44122..8f2f0a04e87 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSPermission.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSPermission.java
@@ -123,6 +123,7 @@ public void setUp() throws IOException {
   public void tearDown() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSRollback.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSRollback.java
index 3fe562608ec..25eb5b685db 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSRollback.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSRollback.java
@@ -346,7 +346,10 @@ private void deleteMatchingFiles(File[] baseDirs, String regex) {
   @After
   public void tearDown() throws Exception {
     LOG.info("Shutting down MiniDFSCluster");
-    if (cluster != null) cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
   
   public static void main(String[] args) throws Exception {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStartupVersions.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStartupVersions.java
index 3a27be6104e..d2022234b88 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStartupVersions.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStartupVersions.java
@@ -282,7 +282,10 @@ public void testVersions() throws Exception {
   @After
   public void tearDown() throws Exception {
     LOG.info("Shutting down MiniDFSCluster");
-    if (cluster != null) cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
   
   public static void main(String[] args) throws Exception {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStorageStateRecovery.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStorageStateRecovery.java
index 176e9cc26cd..cd51631ba8c 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStorageStateRecovery.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStorageStateRecovery.java
@@ -452,6 +452,9 @@ public void setUp() throws Exception {
   @After
   public void tearDown() throws Exception {
     LOG.info("Shutting down MiniDFSCluster");
-    if (cluster != null) cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
 }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStripedInputStream.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStripedInputStream.java
index 495f1b5eeb7..3b8141f329d 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStripedInputStream.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStripedInputStream.java
@@ -86,6 +86,7 @@ public void setup() throws IOException {
   public void tearDown() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStripedOutputStream.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStripedOutputStream.java
index 76b471ad9d2..1846196877a 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStripedOutputStream.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStripedOutputStream.java
@@ -69,6 +69,7 @@ public void setup() throws IOException {
   public void tearDown() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDataTransferKeepalive.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDataTransferKeepalive.java
index dbe2f1e5d17..9e3ddcfbc9a 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDataTransferKeepalive.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDataTransferKeepalive.java
@@ -69,7 +69,10 @@ public void setup() throws Exception {
   
   @After
   public void teardown() {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
   
   /**
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDecommission.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDecommission.java
index 0b70e24aeb0..edc81ae8dc9 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDecommission.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDecommission.java
@@ -126,6 +126,7 @@ public void teardown() throws IOException {
     cleanupFile(localFileSys, dir);
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestEncryptionZones.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestEncryptionZones.java
index b476483de2e..66fef2dca98 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestEncryptionZones.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestEncryptionZones.java
@@ -170,6 +170,7 @@ protected void setProvider() {
   public void teardown() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
     EncryptionFaultInjector.instance = new EncryptionFaultInjector();
   }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestEncryptionZonesWithHA.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestEncryptionZonesWithHA.java
index e61a02b45e6..476d024c7d6 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestEncryptionZonesWithHA.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestEncryptionZonesWithHA.java
@@ -87,6 +87,7 @@ public void setupCluster() throws Exception {
   public void shutdownCluster() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestErasureCodingPolicies.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestErasureCodingPolicies.java
index 84e95b37e9e..dcb528cd542 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestErasureCodingPolicies.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestErasureCodingPolicies.java
@@ -61,6 +61,7 @@ public void setupCluster() throws IOException {
   public void shutdownCluster() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestErasureCodingPolicyWithSnapshot.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestErasureCodingPolicyWithSnapshot.java
index 515763ca083..6b10d7e1837 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestErasureCodingPolicyWithSnapshot.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestErasureCodingPolicyWithSnapshot.java
@@ -57,6 +57,7 @@ public void setupCluster() throws IOException {
   public void shutdownCluster() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestFileConcurrentReader.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestFileConcurrentReader.java
index cd0daf7eb11..e0a0d3be2ed 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestFileConcurrentReader.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestFileConcurrentReader.java
@@ -84,8 +84,10 @@ public void setUp() throws IOException {
 
   @After
   public void tearDown() throws Exception {
-    cluster.shutdown();
-    cluster = null;
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
 
   private void init(Configuration conf) throws IOException {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestFileStatus.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestFileStatus.java
index 29fb54ca330..dcb7af954bf 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestFileStatus.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestFileStatus.java
@@ -77,8 +77,12 @@ public static void testSetUp() throws Exception {
   
   @AfterClass
   public static void testTearDown() throws Exception {
-    fs.close();
-    cluster.shutdown();
+    if (fs != null) {
+      fs.close();
+    }
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
   
   private void checkFile(FileSystem fileSys, Path name, int repl)
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestFileStatusWithECPolicy.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestFileStatusWithECPolicy.java
index 33bea0fd7fd..adb66cabaec 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestFileStatusWithECPolicy.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestFileStatusWithECPolicy.java
@@ -50,6 +50,7 @@ public void before() throws IOException {
   public void after() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestGetFileChecksum.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestGetFileChecksum.java
index 814261f7fe7..cf61e8451bf 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestGetFileChecksum.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestGetFileChecksum.java
@@ -52,6 +52,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestHDFSFileSystemContract.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestHDFSFileSystemContract.java
index f19386b4edd..c1bf6f2f28f 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestHDFSFileSystemContract.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestHDFSFileSystemContract.java
@@ -45,8 +45,10 @@ protected void setUp() throws Exception {
   @Override
   protected void tearDown() throws Exception {
     super.tearDown();
-    cluster.shutdown();
-    cluster = null;
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
 
   @Override
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestHdfsAdmin.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestHdfsAdmin.java
index 245652abde2..0f5bdf5c21d 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestHdfsAdmin.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestHdfsAdmin.java
@@ -47,6 +47,7 @@ public void setUpCluster() throws IOException {
   public void shutDownCluster() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestLeaseRecovery.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestLeaseRecovery.java
index 4ae130df3d2..d62194c16a2 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestLeaseRecovery.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestLeaseRecovery.java
@@ -57,6 +57,7 @@ public class TestLeaseRecovery {
   public void shutdown() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestLeaseRecovery2.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestLeaseRecovery2.java
index 8c389ec0450..13e864441d6 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestLeaseRecovery2.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestLeaseRecovery2.java
@@ -101,8 +101,10 @@ public static void startUp() throws IOException {
    */
   @AfterClass
   public static void tearDown() throws IOException {
-    IOUtils.closeStream(dfs);
-    if (cluster != null) {cluster.shutdown();}
+    if (cluster != null) {
+      IOUtils.closeStream(dfs);
+      cluster.shutdown();
+    }
   }
 
   /**
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestListFilesInDFS.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestListFilesInDFS.java
index 5936d8447dc..53b21d0b514 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestListFilesInDFS.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestListFilesInDFS.java
@@ -46,8 +46,10 @@ public static void testSetUp() throws Exception {
   
   @AfterClass
   public static void testShutdown() throws Exception {
-    fs.close();
-    cluster.shutdown();
+    if (cluster != null) {
+      fs.close();
+      cluster.shutdown();
+    }
   }
   
   protected static Path getTestDir() {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestListFilesInFileContext.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestListFilesInFileContext.java
index 4b0bac94bdf..1e424177e95 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestListFilesInFileContext.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestListFilesInFileContext.java
@@ -83,7 +83,9 @@ private static void writeFile(FileContext fc, Path name, int fileSize)
   
   @AfterClass
   public static void testShutdown() throws Exception {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
 
   /** Test when input path is a file */
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestPipelines.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestPipelines.java
index c9831b0e017..5804d35fef7 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestPipelines.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestPipelines.java
@@ -65,11 +65,14 @@ public void startUpCluster() throws IOException {
 
   @After
   public void shutDownCluster() throws IOException {
-    if (fs != null)
+    if (fs != null) {
       fs.close();
+      fs = null;
+    }
     if (cluster != null) {
       cluster.shutdownDataNodes();
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestReadStripedFileWithDecoding.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestReadStripedFileWithDecoding.java
index ccd300fb628..32b0216d739 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestReadStripedFileWithDecoding.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestReadStripedFileWithDecoding.java
@@ -77,6 +77,7 @@ public void setup() throws IOException {
   public void tearDown() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestReadStripedFileWithMissingBlocks.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestReadStripedFileWithMissingBlocks.java
index b5ffb38b0bf..a362de8351e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestReadStripedFileWithMissingBlocks.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestReadStripedFileWithMissingBlocks.java
@@ -61,6 +61,7 @@ public void setup() throws IOException {
   public void tearDown() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestRecoverStripedFile.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestRecoverStripedFile.java
index 5b9245b1f6f..78349674f70 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestRecoverStripedFile.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestRecoverStripedFile.java
@@ -97,6 +97,7 @@ public void setup() throws IOException {
   public void tearDown() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestReservedRawPaths.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestReservedRawPaths.java
index 82cef944324..84cfd80d287 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestReservedRawPaths.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestReservedRawPaths.java
@@ -91,6 +91,7 @@ public void setup() throws Exception {
   public void teardown() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestSafeMode.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestSafeMode.java
index c26fc753e8e..4940d451d18 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestSafeMode.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestSafeMode.java
@@ -90,9 +90,11 @@ public void startUp() throws IOException {
   public void tearDown() throws IOException {
     if (fs != null) {
       fs.close();
+      fs = null;
     }
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestSafeModeWithStripedFile.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestSafeModeWithStripedFile.java
index 6d711d1f333..acfdddbecf2 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestSafeModeWithStripedFile.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestSafeModeWithStripedFile.java
@@ -63,6 +63,7 @@ public void setup() throws IOException {
   public void tearDown() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestWriteRead.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestWriteRead.java
index 47a78bcc454..623dafff8b9 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestWriteRead.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestWriteRead.java
@@ -86,7 +86,10 @@ public void initJunitModeTest() throws Exception {
 
   @After
   public void shutdown() {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
 
   // Equivalence of @Before for cluster mode testing.
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestWriteReadStripedFile.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestWriteReadStripedFile.java
index 3ea6eea237f..4e5fbe44bd7 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestWriteReadStripedFile.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestWriteReadStripedFile.java
@@ -76,6 +76,7 @@ public void setup() throws IOException {
   public void tearDown() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/protocol/datatransfer/sasl/TestSaslDataTransfer.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/protocol/datatransfer/sasl/TestSaslDataTransfer.java
index 0cbf266aa3e..2d4eb0d2b43 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/protocol/datatransfer/sasl/TestSaslDataTransfer.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/protocol/datatransfer/sasl/TestSaslDataTransfer.java
@@ -67,6 +67,7 @@ public void shutdown() {
     IOUtils.cleanup(null, fs);
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/qjournal/TestSecureNNWithQJM.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/qjournal/TestSecureNNWithQJM.java
index 166f18e5a29..197759edf58 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/qjournal/TestSecureNNWithQJM.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/qjournal/TestSecureNNWithQJM.java
@@ -154,9 +154,11 @@ public void shutdown() throws IOException {
     IOUtils.cleanup(null, fs);
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
     if (mjc != null) {
       mjc.shutdown();
+      mjc = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/qjournal/client/TestQuorumJournalManager.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/qjournal/client/TestQuorumJournalManager.java
index b9a0924c537..3ba573c919a 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/qjournal/client/TestQuorumJournalManager.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/qjournal/client/TestQuorumJournalManager.java
@@ -114,6 +114,7 @@ public void shutdown() throws IOException {
     
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/qjournal/server/TestJournalNodeMXBean.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/qjournal/server/TestJournalNodeMXBean.java
index 498ef71bf80..45b245a64b2 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/qjournal/server/TestJournalNodeMXBean.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/qjournal/server/TestJournalNodeMXBean.java
@@ -61,6 +61,7 @@ public void setup() throws IOException {
   public void cleanup() throws IOException {
     if (jCluster != null) {
       jCluster.shutdown();
+      jCluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/security/TestDelegationToken.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/security/TestDelegationToken.java
index 35c653decef..f4aae8f9859 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/security/TestDelegationToken.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/security/TestDelegationToken.java
@@ -84,6 +84,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if(cluster!=null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlockStatsMXBean.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlockStatsMXBean.java
index 2fe8768bab4..f5b56414bf2 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlockStatsMXBean.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlockStatsMXBean.java
@@ -67,6 +67,7 @@ public void setup() throws IOException {
   public void tearDown() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestComputeInvalidateWork.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestComputeInvalidateWork.java
index 5b08f5302f0..07455cf3a06 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestComputeInvalidateWork.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestComputeInvalidateWork.java
@@ -70,6 +70,7 @@ public void setup() throws Exception {
   public void teardown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestPendingInvalidateBlock.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestPendingInvalidateBlock.java
index 60e0f7c7586..a588a73150e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestPendingInvalidateBlock.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestPendingInvalidateBlock.java
@@ -74,6 +74,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestSequentialBlockGroupId.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestSequentialBlockGroupId.java
index 00b4e3bba37..648745c3480 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestSequentialBlockGroupId.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestSequentialBlockGroupId.java
@@ -93,6 +93,7 @@ public void setup() throws Exception {
   public void teardown() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/BlockReportTestBase.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/BlockReportTestBase.java
index 0a57005ab69..4279f96a001 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/BlockReportTestBase.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/BlockReportTestBase.java
@@ -115,10 +115,12 @@ public void startUpCluster() throws IOException {
   public void shutDownCluster() throws IOException {
     if (fs != null) {
       fs.close();
+      fs = null;
     }
     if (cluster != null) {
       cluster.shutdownDataNodes();
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeExit.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeExit.java
index 7a15b8556dd..918ad83bbd4 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeExit.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeExit.java
@@ -59,8 +59,10 @@ public void setUp() throws IOException {
 
   @After
   public void tearDown() throws Exception {
-    if (cluster != null)
+    if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
+    }
   }
   
   private void stopBPServiceThreads(int numStopThreads, DataNode dn)
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeVolumeFailure.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeVolumeFailure.java
index 2c4fcc5454a..90e000bb3bc 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeVolumeFailure.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeVolumeFailure.java
@@ -116,12 +116,15 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if(data_fail != null) {
       FileUtil.setWritable(data_fail, true);
+      data_fail = null;
     }
     if(failedDir != null) {
       FileUtil.setWritable(failedDir, true);
+      failedDir = null;
     }
     if(cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeVolumeFailureReporting.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeVolumeFailureReporting.java
index 5a58fe46be0..d25a8a2edf4 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeVolumeFailureReporting.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeVolumeFailureReporting.java
@@ -89,6 +89,7 @@ public void tearDown() throws Exception {
     IOUtils.cleanup(LOG, fs);
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeVolumeFailureToleration.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeVolumeFailureToleration.java
index 32a439d1b48..1eb8bcaf77d 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeVolumeFailureToleration.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeVolumeFailureToleration.java
@@ -78,6 +78,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDiskError.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDiskError.java
index 55a668bc61d..000277a8416 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDiskError.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDiskError.java
@@ -71,7 +71,10 @@ public void setUp() throws Exception {
 
   @After
   public void tearDown() throws Exception {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
 
   /**
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestFsDatasetCache.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestFsDatasetCache.java
index cb4022ea910..77b0c447897 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestFsDatasetCache.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestFsDatasetCache.java
@@ -149,9 +149,11 @@ public void tearDown() throws Exception {
     DFSTestUtil.verifyExpectedCacheUsage(0, 0, fsd);
     if (fs != null) {
       fs.close();
+      fs = null;
     }
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
     // Restore the original CacheManipulator
     NativeIO.POSIX.setCacheManipulator(prevCacheManipulator);
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestIncrementalBrVariations.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestIncrementalBrVariations.java
index 0944396807b..f2570c205dc 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestIncrementalBrVariations.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestIncrementalBrVariations.java
@@ -101,10 +101,13 @@ public void startUpCluster() throws IOException {
 
   @After
   public void shutDownCluster() throws IOException {
-    client.close();
-    fs.close();
-    cluster.shutdownDataNodes();
-    cluster.shutdown();
+    if (cluster != null) {
+      client.close();
+      fs.close();
+      cluster.shutdownDataNodes();
+      cluster.shutdown();
+      cluster = null;
+    }
   }
 
   /**
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAclConfigFlag.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAclConfigFlag.java
index afb7dc528ce..36539e59c99 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAclConfigFlag.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAclConfigFlag.java
@@ -58,6 +58,7 @@ public void shutdown() throws Exception {
     IOUtils.cleanup(null, fs);
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAddBlock.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAddBlock.java
index 301ee25ad6b..9e9890f1031 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAddBlock.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAddBlock.java
@@ -60,6 +60,7 @@ public void setup() throws IOException {
   public void tearDown() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAddBlockRetry.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAddBlockRetry.java
index c92e79b76f6..a8cd5b9a825 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAddBlockRetry.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAddBlockRetry.java
@@ -66,6 +66,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAddOverReplicatedStripedBlocks.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAddOverReplicatedStripedBlocks.java
index abcdbc10c08..2be9726379e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAddOverReplicatedStripedBlocks.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAddOverReplicatedStripedBlocks.java
@@ -75,6 +75,7 @@ public void setup() throws IOException {
   public void tearDown() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAddStripedBlocks.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAddStripedBlocks.java
index 836bff1b4a7..7d740121e33 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAddStripedBlocks.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAddStripedBlocks.java
@@ -82,6 +82,7 @@ public void setup() throws IOException {
   public void tearDown() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAuditLogs.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAuditLogs.java
index 0699c31cf3a..37b30637ada 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAuditLogs.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestAuditLogs.java
@@ -137,8 +137,14 @@ public void setupCluster() throws Exception {
   @After
   public void teardownCluster() throws Exception {
     util.cleanup(fs, "/srcdat");
-    fs.close();
-    cluster.shutdown();
+    if (fs != null) {
+      fs.close();
+      fs = null;
+    }
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
 
   /** test that allowed operation puts proper entry in audit log */
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestBackupNode.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestBackupNode.java
index 38d84e35dc5..5ad9d9b41ba 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestBackupNode.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestBackupNode.java
@@ -494,7 +494,9 @@ void testCheckpoint(StartupOption op) throws Exception {
       assertTrue(e.getLocalizedMessage(), false);
     } finally {
       fileSys.close();
-      cluster.shutdown();
+      if (cluster != null) {
+        cluster.shutdown();
+      }
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestBlockPlacementPolicyRackFaultTolerant.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestBlockPlacementPolicyRackFaultTolerant.java
index ca9da77218f..9f844d7fc7e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestBlockPlacementPolicyRackFaultTolerant.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestBlockPlacementPolicyRackFaultTolerant.java
@@ -83,6 +83,7 @@ public void setup() throws IOException {
   public void teardown() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestCacheDirectives.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestCacheDirectives.java
index 5977dbf61f9..45d819e50a9 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestCacheDirectives.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestCacheDirectives.java
@@ -158,6 +158,7 @@ public void teardown() throws Exception {
     waitForCachedBlocks(namenode, 0, 0, "teardown");
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
     // Restore the original CacheManipulator
     NativeIO.POSIX.setCacheManipulator(prevCacheManipulator);
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestCommitBlockWithInvalidGenStamp.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestCommitBlockWithInvalidGenStamp.java
index d2b2b5a08fe..77a32680f32 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestCommitBlockWithInvalidGenStamp.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestCommitBlockWithInvalidGenStamp.java
@@ -58,6 +58,7 @@ public void setUp() throws IOException {
   public void tearDown() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDeadDatanode.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDeadDatanode.java
index 875ba4a224d..7fd0c300462 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDeadDatanode.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDeadDatanode.java
@@ -62,7 +62,10 @@ public class TestDeadDatanode {
 
   @After
   public void cleanup() {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
 
   /**
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDefaultBlockPlacementPolicy.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDefaultBlockPlacementPolicy.java
index 5709cee8be7..a54040b2e8d 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDefaultBlockPlacementPolicy.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDefaultBlockPlacementPolicy.java
@@ -71,6 +71,7 @@ public void setup() throws IOException {
   public void teardown() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDiskspaceQuotaUpdate.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDiskspaceQuotaUpdate.java
index cf6463836e8..d459db09b2e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDiskspaceQuotaUpdate.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDiskspaceQuotaUpdate.java
@@ -71,6 +71,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestEditLogAutoroll.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestEditLogAutoroll.java
index 3a0ae5c5f2a..f22ee2fcc24 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestEditLogAutoroll.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestEditLogAutoroll.java
@@ -97,9 +97,11 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (fs != null) {
       fs.close();
+      fs = null;
     }
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestEditLogJournalFailures.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestEditLogJournalFailures.java
index 610a4a2fd4c..51dfc3e993d 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestEditLogJournalFailures.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestEditLogJournalFailures.java
@@ -70,11 +70,14 @@ public void setUpMiniCluster(Configuration conf, boolean manageNameDfsDirs)
   
   @After
   public void shutDownMiniCluster() throws IOException {
-    if (fs != null)
+    if (fs != null) {
       fs.close();
+      fs = null;
+    }
     if (cluster != null) {
       try {
         cluster.shutdown();
+        cluster = null;
       } catch (ExitException ee) {
         // Ignore ExitExceptions as the tests may result in the
         // NameNode doing an immediate shutdown.
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSDirectory.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSDirectory.java
index 11905bd4479..2b43c0f9536 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSDirectory.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSDirectory.java
@@ -108,6 +108,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSImageWithAcl.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSImageWithAcl.java
index 690fec6aaeb..48d3dea81c3 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSImageWithAcl.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSImageWithAcl.java
@@ -55,7 +55,9 @@ public static void setUp() throws IOException {
 
   @AfterClass
   public static void tearDown() {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
 
   private void testAcl(boolean persistNamespace) throws IOException {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSImageWithSnapshot.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSImageWithSnapshot.java
index e23fbf0dd89..1904bbc122e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSImageWithSnapshot.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSImageWithSnapshot.java
@@ -89,6 +89,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSImageWithXAttr.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSImageWithXAttr.java
index bb6642f6155..4cef3214e9b 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSImageWithXAttr.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFSImageWithXAttr.java
@@ -62,7 +62,9 @@ public static void setUp() throws IOException {
 
   @AfterClass
   public static void tearDown() {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
 
   private void testXAttr(boolean persistNamespace) throws IOException {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFileTruncate.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFileTruncate.java
index 1c739fc715c..56846af8769 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFileTruncate.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFileTruncate.java
@@ -110,8 +110,14 @@ public void setUp() throws IOException {
 
   @After
   public void tearDown() throws IOException {
-    if(fs != null)      fs.close();
-    if(cluster != null) cluster.shutdown();
+    if(fs != null) {
+      fs.close();
+      fs = null;
+    }
+    if(cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
 
   /**
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestHDFSConcat.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestHDFSConcat.java
index 6dc0782ab47..b5e0efe0649 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestHDFSConcat.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestHDFSConcat.java
@@ -84,10 +84,12 @@ public void startUpCluster() throws IOException {
   public void shutDownCluster() throws IOException {
     if(dfs != null) {
       dfs.close();
+      dfs = null;
     }
     if(cluster != null) {
       cluster.shutdownDataNodes();
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestINodeAttributeProvider.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestINodeAttributeProvider.java
index c5f428bea4b..ffdc5356ac2 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestINodeAttributeProvider.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestINodeAttributeProvider.java
@@ -186,6 +186,7 @@ public void cleanUp() throws IOException {
     CALLED.clear();
     if (miniDFS != null) {
       miniDFS.shutdown();
+      miniDFS = null;
     }
     Assert.assertTrue(CALLED.contains("stop"));
   }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestMalformedURLs.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestMalformedURLs.java
index b85e5ee447c..0c71445b0eb 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestMalformedURLs.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestMalformedURLs.java
@@ -54,6 +54,7 @@ public void testTryStartingCluster() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestMetadataVersionOutput.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestMetadataVersionOutput.java
index d426de57636..dc8f70a5b5b 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestMetadataVersionOutput.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestMetadataVersionOutput.java
@@ -45,6 +45,7 @@ public class TestMetadataVersionOutput {
   public void tearDown() throws Exception {
     if (dfsCluster != null) {
       dfsCluster.shutdown();
+      dfsCluster = null;
     }
     Thread.sleep(2000);
   }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeMetadataConsistency.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeMetadataConsistency.java
index 917119416d1..d4fb0d17cc5 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeMetadataConsistency.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeMetadataConsistency.java
@@ -63,6 +63,7 @@ public void InitTest() throws IOException {
   public void cleanup() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeRetryCacheMetrics.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeRetryCacheMetrics.java
index 97158108848..fb3a84083cd 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeRetryCacheMetrics.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeRetryCacheMetrics.java
@@ -80,6 +80,7 @@ public void setup() throws Exception {
   public void cleanup() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeRpcServerMethods.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeRpcServerMethods.java
index 80d97224d6d..a32e2188e88 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeRpcServerMethods.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeRpcServerMethods.java
@@ -55,8 +55,10 @@ public void setup() throws Exception {
    */
   @After
   public void cleanup() throws IOException {
-    if (cluster != null)
+    if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
+    }
   }
 
   @Test
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNamenodeRetryCache.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNamenodeRetryCache.java
index 2e6b4a336df..767562cf9ce 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNamenodeRetryCache.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNamenodeRetryCache.java
@@ -105,7 +105,10 @@ public void setup() throws Exception {
    * @throws AccessControlException */
   @After
   public void cleanup() throws IOException {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
   
   /** Set the current Server RPC call */
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestQuotaByStorageType.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestQuotaByStorageType.java
index f56c5a2d062..ee02fd0f9f8 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestQuotaByStorageType.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestQuotaByStorageType.java
@@ -74,6 +74,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestQuotaWithStripedBlocks.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestQuotaWithStripedBlocks.java
index 08a17445a30..9aa0e07c85b 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestQuotaWithStripedBlocks.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestQuotaWithStripedBlocks.java
@@ -76,6 +76,7 @@ public void setUp() throws IOException {
   public void tearDown() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestXAttrConfigFlag.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestXAttrConfigFlag.java
index e4fb4bbad9b..5064a0339d2 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestXAttrConfigFlag.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestXAttrConfigFlag.java
@@ -51,6 +51,7 @@ public void shutdown() throws Exception {
     IOUtils.cleanup(null, fs);
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestBootstrapStandby.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestBootstrapStandby.java
index 9f0d95bfa94..8c39548fc83 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestBootstrapStandby.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestBootstrapStandby.java
@@ -90,6 +90,7 @@ public void setupCluster() throws IOException {
   public void shutdownCluster() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestBootstrapStandbyWithQJM.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestBootstrapStandbyWithQJM.java
index db9a2de7164..10194baf2dd 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestBootstrapStandbyWithQJM.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestBootstrapStandbyWithQJM.java
@@ -81,9 +81,11 @@ public void setup() throws Exception {
   public void cleanup() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
     if (jCluster != null) {
       jCluster.shutdown();
+      jCluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestDNFencing.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestDNFencing.java
index 4260d94664d..96822d625b1 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestDNFencing.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestDNFencing.java
@@ -118,6 +118,7 @@ public void shutdownCluster() throws Exception {
       banner("Shutting down cluster. NN2 metadata:");
       doMetasave(nn2);
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestDelegationTokensWithHA.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestDelegationTokensWithHA.java
index 2daa9f87181..16b27d87851 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestDelegationTokensWithHA.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestDelegationTokensWithHA.java
@@ -107,6 +107,7 @@ public void setupCluster() throws Exception {
   public void shutdownCluster() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestFailoverWithBlockTokensEnabled.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestFailoverWithBlockTokensEnabled.java
index 116079a62ec..43ab69d82d1 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestFailoverWithBlockTokensEnabled.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestFailoverWithBlockTokensEnabled.java
@@ -77,6 +77,7 @@ public void startCluster() throws IOException {
   public void shutDownCluster() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestFailureToReadEdits.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestFailureToReadEdits.java
index f5a72cae00e..f82b6164fca 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestFailureToReadEdits.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestFailureToReadEdits.java
@@ -130,15 +130,18 @@ public void setUpCluster() throws Exception {
   public void tearDownCluster() throws Exception {
     if (fs != null) {
       fs.close();
+      fs = null;
     }
     
     if (clusterType == TestType.SHARED_DIR_HA) {
       if (cluster != null) {
         cluster.shutdown();
+        cluster = null;
       }
     } else {
       if (miniQjmHaCluster != null) {
         miniQjmHaCluster.shutdown();
+        miniQjmHaCluster = null;
       }
     }
   }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestGetGroupsWithHA.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestGetGroupsWithHA.java
index e548817b6a7..c3c22759d96 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestGetGroupsWithHA.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestGetGroupsWithHA.java
@@ -46,6 +46,7 @@ public void setUpNameNode() throws IOException {
   public void tearDownNameNode() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestHASafeMode.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestHASafeMode.java
index 21de9606971..4b1d27d5b90 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestHASafeMode.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestHASafeMode.java
@@ -112,6 +112,7 @@ public void setupCluster() throws Exception {
   public void shutdownCluster() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestInitializeSharedEdits.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestInitializeSharedEdits.java
index 272e5436434..856ed8fbc86 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestInitializeSharedEdits.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestInitializeSharedEdits.java
@@ -78,6 +78,7 @@ public void setupCluster() throws IOException {
   public void shutdownCluster() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestNNHealthCheck.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestNNHealthCheck.java
index 6519588ce51..22d4ef41afc 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestNNHealthCheck.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestNNHealthCheck.java
@@ -53,6 +53,7 @@ public void setup() {
   public void shutdown() {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestQuotasWithHA.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestQuotasWithHA.java
index db67d95bce9..e768306cfa5 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestQuotasWithHA.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestQuotasWithHA.java
@@ -80,6 +80,7 @@ public void setupCluster() throws Exception {
   public void shutdownCluster() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestRetryCacheWithHA.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestRetryCacheWithHA.java
index f3221b19c02..b4c383afa2f 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestRetryCacheWithHA.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestRetryCacheWithHA.java
@@ -148,6 +148,7 @@ public void setup() throws Exception {
   public void cleanup() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestStandbyCheckpoints.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestStandbyCheckpoints.java
index cd32502d8c6..37d346aafca 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestStandbyCheckpoints.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestStandbyCheckpoints.java
@@ -139,6 +139,7 @@ protected Configuration setupCommonConfig() {
   public void shutdownCluster() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestXAttrsWithHA.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestXAttrsWithHA.java
index db92238a3e1..bb44d05e2c6 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestXAttrsWithHA.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestXAttrsWithHA.java
@@ -82,6 +82,7 @@ public void setupCluster() throws Exception {
   public void shutdownCluster() throws IOException {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/metrics/TestNNMetricFilesInGetListingOps.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/metrics/TestNNMetricFilesInGetListingOps.java
index 47a893dfd2c..110615d9098 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/metrics/TestNNMetricFilesInGetListingOps.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/metrics/TestNNMetricFilesInGetListingOps.java
@@ -62,7 +62,10 @@ public void setUp() throws Exception {
 
   @After
   public void tearDown() throws Exception {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
 
   /** create a file with a length of <code>fileLen</code> */
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/metrics/TestNameNodeMetrics.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/metrics/TestNameNodeMetrics.java
index 067d465b3ee..a9eeaac0f58 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/metrics/TestNameNodeMetrics.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/metrics/TestNameNodeMetrics.java
@@ -124,7 +124,10 @@ public void tearDown() throws Exception {
       MetricsRecordBuilder rb = getMetrics(source);
       assertQuantileGauges("GetGroups1s", rb);
     }
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
   
   /** create a file with a length of <code>fileLen</code> */
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestFileContextSnapshot.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestFileContextSnapshot.java
index dcabed7be38..a6cd1dd9b5a 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestFileContextSnapshot.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestFileContextSnapshot.java
@@ -67,6 +67,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestGetContentSummaryWithSnapshot.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestGetContentSummaryWithSnapshot.java
index 21f2db52c50..dc6f584a2b8 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestGetContentSummaryWithSnapshot.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestGetContentSummaryWithSnapshot.java
@@ -70,6 +70,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestINodeFileUnderConstructionWithSnapshot.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestINodeFileUnderConstructionWithSnapshot.java
index 16044c3eda1..65b2f8c3f93 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestINodeFileUnderConstructionWithSnapshot.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestINodeFileUnderConstructionWithSnapshot.java
@@ -91,6 +91,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestNestedSnapshots.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestNestedSnapshots.java
index d565dad0db8..5b7ed41f42e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestNestedSnapshots.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestNestedSnapshots.java
@@ -78,6 +78,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestOpenFilesWithSnapshot.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestOpenFilesWithSnapshot.java
index f0c5482659e..694d15e63f3 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestOpenFilesWithSnapshot.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestOpenFilesWithSnapshot.java
@@ -52,9 +52,11 @@ public void setup() throws IOException {
   public void teardown() throws IOException {
     if (fs != null) {
       fs.close();
+      fs = null;
     }
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
 
   }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestRenameWithSnapshots.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestRenameWithSnapshots.java
index ab97a3d1f83..827feb6a2a8 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestRenameWithSnapshots.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestRenameWithSnapshots.java
@@ -122,6 +122,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSetQuotaWithSnapshot.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSetQuotaWithSnapshot.java
index 89e7416a4a9..c5ac26ed95a 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSetQuotaWithSnapshot.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSetQuotaWithSnapshot.java
@@ -76,6 +76,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshot.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshot.java
index 89a5dd9bd40..6313ce1aa4d 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshot.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshot.java
@@ -131,6 +131,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotBlocksMap.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotBlocksMap.java
index ebb02807a48..76f1e8f8beb 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotBlocksMap.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotBlocksMap.java
@@ -84,6 +84,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotDeletion.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotDeletion.java
index b81291a9d60..bf462da2f0f 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotDeletion.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotDeletion.java
@@ -106,6 +106,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
     
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotDiffReport.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotDiffReport.java
index 786f9249f69..453afacddac 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotDiffReport.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotDiffReport.java
@@ -71,6 +71,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotListing.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotListing.java
index 2639d445ac6..03a2ff4e64e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotListing.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotListing.java
@@ -61,6 +61,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotMetrics.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotMetrics.java
index 1b8f43743f5..f64caff75bc 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotMetrics.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotMetrics.java
@@ -69,6 +69,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotRename.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotRename.java
index 731b97baf6b..8c8fca71e82 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotRename.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotRename.java
@@ -82,6 +82,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotReplication.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotReplication.java
index 30f6fee4db7..d073228a700 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotReplication.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshotReplication.java
@@ -75,6 +75,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshottableDirListing.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshottableDirListing.java
index 89888060741..5611eb925a6 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshottableDirListing.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestSnapshottableDirListing.java
@@ -67,6 +67,7 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
   
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestDFSHAAdminMiniCluster.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestDFSHAAdminMiniCluster.java
index 06f9ccbefea..a21a31d9e0f 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestDFSHAAdminMiniCluster.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestDFSHAAdminMiniCluster.java
@@ -82,7 +82,10 @@ public void setup() throws IOException {
 
   @After
   public void shutdown() throws Exception {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
   
   @Test
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestDFSZKFailoverController.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestDFSZKFailoverController.java
index 3e1c96f84df..94cccedc02f 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestDFSZKFailoverController.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestDFSZKFailoverController.java
@@ -111,16 +111,22 @@ public void setup() throws Exception {
   
   @After
   public void shutdown() throws Exception {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
     
     if (thr1 != null) {
       thr1.interrupt();
+      thr1 = null;
     }
     if (thr2 != null) {
       thr2.interrupt();
+      thr2 = null;
     }
     if (ctx != null) {
       ctx.stop();
+      ctx = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestGetGroups.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestGetGroups.java
index d02ec9620c2..3d9631dfe12 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestGetGroups.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestGetGroups.java
@@ -42,7 +42,10 @@ public void setUpNameNode() throws IOException {
   
   @After
   public void tearDownNameNode() {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
   }
 
   @Override
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestStoragePolicyCommands.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestStoragePolicyCommands.java
index cb249e6cc06..ec0bb665de4 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestStoragePolicyCommands.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/TestStoragePolicyCommands.java
@@ -54,9 +54,11 @@ public void clusterSetUp() throws IOException {
   public void clusterShutdown() throws IOException{
     if(fs != null) {
       fs.close();
+      fs = null;
     }
     if(cluster != null) {
       cluster.shutdown();
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestHttpsFileSystem.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestHttpsFileSystem.java
index 6d541e4ddc5..0f0ac3bf103 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestHttpsFileSystem.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestHttpsFileSystem.java
@@ -79,7 +79,9 @@ public static void setUp() throws Exception {
 
   @AfterClass
   public static void tearDown() throws Exception {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+    }
     FileUtil.fullyDelete(new File(BASEDIR));
     KeyStoreTestUtil.cleanupSSLConfig(keystoresDir, sslConfDir);
   }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestWebHdfsWithAuthenticationFilter.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestWebHdfsWithAuthenticationFilter.java
index 09c78728a9e..f21fde46224 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestWebHdfsWithAuthenticationFilter.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestWebHdfsWithAuthenticationFilter.java
@@ -84,8 +84,12 @@ public static void setUp() throws IOException {
 
   @AfterClass
   public static void tearDown() throws IOException {
-    fs.close();
-    cluster.shutdown();
+    if (fs != null) {
+      fs.close();
+    }
+    if (cluster != null) {
+      cluster.shutdown();
+    }
   }
 
   @Test
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/security/TestRefreshUserMappings.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/security/TestRefreshUserMappings.java
index ca67245371b..c76033c4a56 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/security/TestRefreshUserMappings.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/security/TestRefreshUserMappings.java
@@ -99,10 +99,12 @@ public void setUp() throws Exception {
   public void tearDown() throws Exception {
     if(cluster!=null) {
       cluster.shutdown();
+      cluster = null;
     }
     if(tempResource!=null) {
       File f = new File(tempResource);
       f.delete();
+      tempResource = null;
     }
   }
     
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/tools/TestJMXGet.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/tools/TestJMXGet.java
index be3ef484048..a9e41ec1777 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/tools/TestJMXGet.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/tools/TestJMXGet.java
@@ -73,13 +73,16 @@ public void setUp() throws Exception {
    */
   @After
   public void tearDown() throws Exception {
-    if(cluster.isClusterUp())
-      cluster.shutdown();
-
-    File data_dir = new File(cluster.getDataDirectory());
-    if(data_dir.exists() && !FileUtil.fullyDelete(data_dir)) {
-      throw new IOException("Could not delete hdfs directory in tearDown '"
-          + data_dir + "'");
+    if (cluster != null) {
+      if (cluster.isClusterUp()) {
+        cluster.shutdown();
+      }
+      File data_dir = new File(cluster.getDataDirectory());
+      if (data_dir.exists() && !FileUtil.fullyDelete(data_dir)) {
+        throw new IOException(
+            "Could not delete hdfs directory in tearDown '" + data_dir + "'");
+      }
+      cluster = null;
     }
   }
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/tracing/TestTracing.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/tracing/TestTracing.java
index 7d7144148fc..bdad46a4e6f 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/tracing/TestTracing.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/tracing/TestTracing.java
@@ -222,7 +222,10 @@ public void startCluster() throws IOException {
 
   @After
   public void shutDown() throws IOException {
-    cluster.shutdown();
+    if (cluster != null) {
+      cluster.shutdown();
+      cluster = null;
+    }
     FsTracer.clear();
   }
 }