HDFS-16702. MiniDFSCluster should report cause of exception in assertion error

Author: virajjasani

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/ExitUtil.java

@@ -94,7 +94,12 @@ public String toString() {
       if (message == null) {
         message = super.toString();
       }
-      return Integer.toString(status) + ": " + message;
+      String finalString = status + ": " + message;
+      Throwable cause = getCause();
+      if (cause != null) {
+        finalString = finalString + " : \n" + "cause: " + cause.getMessage();
+      }
+      return finalString;
     }
   }
 
@@ -139,7 +144,12 @@ public String toString() {
       if (message == null) {
         message = super.toString();
       }
-      return Integer.toString(status) + ": " + message;
+      String finalString = status + ": " + message;
+      Throwable cause = getCause();
+      if (cause != null) {
+        finalString = finalString + " : \n" + "cause: " + cause.getMessage();
+      }
+      return finalString;
     }
 
   }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/MiniDFSCluster.java

@@ -2159,10 +2159,10 @@ public void shutdown(boolean deleteDfsDir, boolean closeFileSystem) {
     LOG.info("Shutting down the Mini HDFS Cluster");
     if (checkExitOnShutdown)  {
       if (ExitUtil.terminateCalled()) {
-        LOG.error("Test resulted in an unexpected exit",
-            ExitUtil.getFirstExitException());
+        ExitUtil.ExitException exitException = ExitUtil.getFirstExitException();
+        LOG.error("Test resulted in an unexpected exit", exitException);
         ExitUtil.resetFirstExitException();
-        throw new AssertionError("Test resulted in an unexpected exit");
+        throw new AssertionError("Test resulted in an unexpected exit", exitException);
       }
     }
     if (closeFileSystem) {