diff --git a/paddle/fluid/framework/operator.cc b/paddle/fluid/framework/operator.cc
index a103be7191d02a96ee97d76f786f9364938c1c65..6666dd8e60a509c3f82f66f832ecce03811e9fb6 100644
--- a/paddle/fluid/framework/operator.cc
+++ b/paddle/fluid/framework/operator.cc
@@ -544,11 +544,13 @@ class RuntimeInferShapeContext : public InferShapeContext {
 
   void ShareLoD(const std::string& in, const std::string& out, size_t i = 0,
                 size_t j = 0) const override {
-    PADDLE_ENFORCE_LT(i, Inputs(in).size());
-    PADDLE_ENFORCE_LT(j, Outputs(out).size());
-    Variable* in_var = scope_.FindVar(Inputs(in)[i]);
-    Variable* out_var = scope_.FindVar(Outputs(out)[j]);
+    const std::vector<std::string>& inputs = Inputs(in);
+    const std::vector<std::string>& outputs = Outputs(out);
+    PADDLE_ENFORCE_LT(i, inputs.size());
+    PADDLE_ENFORCE_LT(j, outputs.size());
+    Variable* in_var = scope_.FindVar(inputs.at(i));
     if (!in_var->IsType<LoDTensor>()) return;
+    Variable* out_var = scope_.FindVar(outputs.at(j));
     PADDLE_ENFORCE(out_var->IsType<LoDTensor>(),
                    "The %d-th output of Output(%s) must be LoDTensor.", j, out);
     auto in_tensor = in_var->Get<LoDTensor>();
@@ -576,20 +578,6 @@ class RuntimeInferShapeContext : public InferShapeContext {
       out_tensor->set_layout(in_tensor.layout());
   }
 
-  void ShareLayout(const std::string& in, const std::string& out, size_t i = 0,
-                   size_t j = 0) const {
-    PADDLE_ENFORCE_LT(i, Inputs(in).size());
-    PADDLE_ENFORCE_LT(j, Outputs(out).size());
-    Variable* in_var = scope_.FindVar(Inputs(in)[i]);
-    Variable* out_var = scope_.FindVar(Outputs(out)[j]);
-    if (!in_var->IsType<LoDTensor>()) return;
-    PADDLE_ENFORCE(out_var->IsType<LoDTensor>(),
-                   "The %d-th output of Output(%s) must be LoDTensor.", j, out);
-    auto in_tensor = in_var->Get<LoDTensor>();
-    auto* out_tensor = out_var->GetMutable<LoDTensor>();
-    out_tensor->set_layout(in_tensor.layout());
-  }
-
   bool IsRuntime() const override { return true; }
 
  protected:
diff --git a/paddle/fluid/framework/shape_inference.cc b/paddle/fluid/framework/shape_inference.cc
index 89eb00ff65598eff5f4ba541df107e8da04e1a89..ddff2c7c261746ac9986e79cff3da7e0a9654adc 100644
--- a/paddle/fluid/framework/shape_inference.cc
+++ b/paddle/fluid/framework/shape_inference.cc
@@ -46,16 +46,6 @@ std::vector<DDim> InferShapeContext::GetReaderDims(
   return this->GetRepeatedDims(arg_names[0]);
 }
 
-void InferShapeContext::ShareLoDs(const std::string &in,
-                                  const std::string &out) const {
-  PADDLE_ENFORCE_EQ(Inputs(in).size(), Outputs(out).size(),
-                    "The number of arguments in %s and %s is not equal.", in,
-                    out);
-  for (size_t i = 0; i < in.size(); ++i) {
-    ShareLoD(in, out, i, i);
-  }
-}
-
 DDim InferShapeContext::GetInputsElementDim(const std::string &name,
                                             int idx) const {
   const std::vector<std::string> &names = Inputs(name);
diff --git a/paddle/fluid/framework/shape_inference.h b/paddle/fluid/framework/shape_inference.h
index fd220d961af85dd55fe2031409180823d8f178fc..5f497cafa0f75f7c23d550ef767d55274de7c900 100644
--- a/paddle/fluid/framework/shape_inference.h
+++ b/paddle/fluid/framework/shape_inference.h
@@ -56,8 +56,6 @@ class InferShapeContext {
   virtual const std::vector<std::string> &Outputs(
       const std::string &name) const = 0;
 
-  void ShareLoDs(const std::string &in, const std::string &out) const;
-
   virtual void ShareLoD(const std::string &in, const std::string &out,
                         size_t i = 0, size_t j = 0) const = 0;
 
diff --git a/python/paddle/reader/decorator.py b/python/paddle/reader/decorator.py
index 5b9459b670ac8583ee0e65a3c1b51f6248bb6303..b2ef9f75809004d9df0003217c2dafcd69e83890 100644
--- a/python/paddle/reader/decorator.py
+++ b/python/paddle/reader/decorator.py
@@ -15,7 +15,7 @@
 __all__ = [
     'map_readers', 'buffered', 'compose', 'chain', 'shuffle',
     'ComposeNotAligned', 'firstn', 'xmap_readers', 'PipeReader',
-    'multiprocess_reader'
+    'multiprocess_reader', 'Fake'
 ]
 
 from threading import Thread
@@ -504,3 +504,39 @@ class PipeReader:
                     yield decomp_buff
             else:
                 break
+
+
+class Fake(object):
+    """
+    fake reader will cache the first data it read and yield it out for data_num times.
+    It is used to cache a data from real reader and use it for speed testing.
+
+    :param reader: the origin reader
+    :param data_num: times that this reader will yield data.
+
+    :return: a fake reader.
+
+    Examples:
+        .. code-block:: python
+
+            def reader():
+                for i in range(10):
+                    yield i
+
+            fake_reader = Fake()(reader, 100)
+    """
+
+    def __init__(self):
+        self.data = None
+        self.yield_num = 0
+
+    def __call__(self, reader, data_num):
+        def fake_reader():
+            if self.data is None:
+                self.data = next(reader())
+            while self.yield_num < data_num:
+                yield self.data
+                self.yield_num += 1
+            self.yield_num = 0
+
+        return fake_reader
diff --git a/python/paddle/reader/tests/decorator_test.py b/python/paddle/reader/tests/decorator_test.py
index c324092f8850e4bd64955aa9c987746b5cec54b5..b9af8348e16c051db64d57a9594aee303d83aef2 100644
--- a/python/paddle/reader/tests/decorator_test.py
+++ b/python/paddle/reader/tests/decorator_test.py
@@ -203,5 +203,21 @@ class TestMultiProcessReader(unittest.TestCase):
         self.reader_test(use_pipe=True)
 
 
+class TestFakeReader(unittest.TestCase):
+    def test_fake_reader(self):
+        def reader():
+            for i in range(10):
+                yield i
+
+        data_num = 100
+        fake_reader = paddle.reader.Fake()(reader, data_num)
+        for _ in range(10):
+            i = 0
+            for data in fake_reader():
+                self.assertEqual(data, 0)
+                i += 1
+            self.assertEqual(i, data_num)
+
+
 if __name__ == '__main__':
     unittest.main()