HDFS-11967. TestJMXGet fails occasionally. Contributed by Arpit Agarwal.

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/tools/TestJMXGet.java

@@ -141,7 +141,7 @@ public class TestJMXGet {
     byte[] bytes = null;
     String pattern = "List of all the available keys:";
     PipedOutputStream pipeOut = new PipedOutputStream();
-    PipedInputStream pipeIn = new PipedInputStream(pipeOut);
+    PipedInputStream pipeIn = new PipedInputStream(pipeOut, 1024 * 1024);
     PrintStream oldErr = System.err;
     System.setErr(new PrintStream(pipeOut));
     try {