HADOOP-17914. Print RPC response length in the exception message (#3436)

Author: tomscut

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Client.java

@@ -1907,10 +1907,12 @@ public ByteBuffer readResponse() throws IOException {
         }
       }
       if (length <= 0) {
-        throw new RpcException("RPC response has invalid length");
+        throw new RpcException(String.format("RPC response has " +
+            "invalid length of %d", length));
       }
       if (maxResponseLength > 0 && length > maxResponseLength) {
-        throw new RpcException("RPC response exceeds maximum data length");
+        throw new RpcException(String.format("RPC response has a " +
+            "length of %d exceeds maximum data length", length));
       }
       ByteBuffer bb = ByteBuffer.allocate(length);
       in.readFully(bb.array());

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/ipc/TestIPC.java

@@ -1638,8 +1638,8 @@ public void testRpcResponseLimit() throws Throwable {
     } catch (IOException ioe) {
       Assert.assertNotNull(ioe);
       Assert.assertEquals(RpcException.class, ioe.getClass());
-      Assert.assertEquals("RPC response exceeds maximum data length",
-          ioe.getMessage());
+      Assert.assertTrue(ioe.getMessage().contains(
+          "exceeds maximum data length"));
       return;
     }
     Assert.fail("didn't get limit exceeded");