diff --git a/python/paddle/fluid/layers/io.py b/python/paddle/fluid/layers/io.py
index 34cdac52d33000cfb87a97a1486abe7a4a583bbd..0665c09bfb52c932219be68ca801cfa951d672d3 100644
--- a/python/paddle/fluid/layers/io.py
+++ b/python/paddle/fluid/layers/io.py
@@ -22,8 +22,7 @@ from ..executor import global_scope
 from layer_function_generator import generate_layer_fn, templatedoc
 
 __all__ = [
-    'data', 'BlockGuardServ', 'ListenAndServ', 'Send', 'Recv',
-    'open_recordio_file', 'open_files', 'read_file', 'shuffle', 'batch',
+    'data', 'open_recordio_file', 'open_files', 'read_file', 'shuffle', 'batch',
     'double_buffer', 'random_data_generator', 'py_reader', 'Preprocessor',
     'load'
 ]
@@ -802,7 +801,7 @@ class Preprocessor(object):
         self.sink_var_names = None
         self.status = Preprocessor.BEFORE_SUB_BLOCK
 
-    def is_completed(self):
+    def _is_completed(self):
         return self.sub_block and self.source_var_names and self.sink_var_names
 
     @contextlib.contextmanager
@@ -812,7 +811,7 @@ class Preprocessor(object):
         yield
         self.main_prog.rollback()
         self.status = Preprocessor.AFTER_SUB_BLOCK
-        if not self.is_completed():
+        if not self._is_completed():
             raise RuntimeError(
                 "The definition of preprocessor is incompleted! "
                 "Please make sure that you have set input and output "
diff --git a/python/paddle/fluid/tests/unittests/test_dist_train.py b/python/paddle/fluid/tests/unittests/test_dist_train.py
index 562e66b0625083fe840d64967249f0215cfda1f9..aab8969a96ff69d1a306506337a0e009f14758b9 100644
--- a/python/paddle/fluid/tests/unittests/test_dist_train.py
+++ b/python/paddle/fluid/tests/unittests/test_dist_train.py
@@ -22,6 +22,9 @@ import numpy
 
 import paddle.fluid as fluid
 import paddle.fluid.layers as layers
+from paddle.fluid.layers.io import ListenAndServ
+from paddle.fluid.layers.io import Recv
+from paddle.fluid.layers.io import Send
 
 
 class TestSendOp(unittest.TestCase):
@@ -65,8 +68,7 @@ class TestSendOp(unittest.TestCase):
         main = fluid.Program()
 
         with fluid.program_guard(main):
-            serv = layers.ListenAndServ(
-                "127.0.0.1:0", ["X"], optimizer_mode=False)
+            serv = ListenAndServ("127.0.0.1:0", ["X"], optimizer_mode=False)
             with serv.do():
                 out_var = main.global_block().create_var(
                     name="scale_0.tmp_0",
@@ -99,8 +101,8 @@ class TestSendOp(unittest.TestCase):
                 persistable=False,
                 shape=[32, 32])
             fluid.initializer.Constant(value=2.3)(get_var, main.global_block())
-            layers.Send("127.0.0.1:%d" % port, [x])
-            o = layers.Recv("127.0.0.1:%d" % port, [get_var])
+            Send("127.0.0.1:%d" % port, [x])
+            o = Recv("127.0.0.1:%d" % port, [get_var])
 
         exe = fluid.Executor(place)
         self.dist_out = exe.run(main, fetch_list=o)  # o is a list