diff --git a/paddle/framework/channel_test.cc b/paddle/framework/channel_test.cc
index 35567649b888d0c99e0025778284617483a92ebb..d7140dd10661c7b8582930b47872ab0b330c4d66 100644
--- a/paddle/framework/channel_test.cc
+++ b/paddle/framework/channel_test.cc
@@ -176,7 +176,7 @@ TEST(Channel, ConcurrentSendNonConcurrentReceiveWithSufficientBufferSize) {
       sum += i;
     }
   });
-  std::this_thread::sleep_for(std::chrono::milliseconds(100));  // wait 0.5 sec
+  std::this_thread::sleep_for(std::chrono::milliseconds(100));  // wait 0.1 sec
   EXPECT_EQ(sum, 45U);
 
   CloseChannel(ch);
@@ -194,10 +194,7 @@ TEST(Channel, RecevingOrderEqualToSendingOrderWithBufferedChannel) {
   RecevingOrderEqualToSendingOrder(ch);
 }
 
-// This tests that closing a buffered channel also unblocks
-//  any receivers waiting on the channel
-TEST(Channel, BufferedChannelCloseUnblocksReceiversTest) {
-  auto ch = MakeChannel<int>(1);
+void ChannelCloseUnblocksReceiversTest(Channel<int> *ch) {
   size_t num_threads = 5;
   std::thread t[num_threads];
   bool thread_ended[num_threads];
@@ -208,15 +205,14 @@ TEST(Channel, BufferedChannelCloseUnblocksReceiversTest) {
     t[i] = std::thread(
         [&](bool *p) {
           int data;
-          // All reads should return false
           EXPECT_EQ(ch->Receive(&data), false);
           *p = true;
         },
         &thread_ended[i]);
   }
-  std::this_thread::sleep_for(std::chrono::milliseconds(100));  // wait
+  std::this_thread::sleep_for(std::chrono::milliseconds(100));  // wait 0.1 sec
 
-  // Verify that all threads are blocked
+  // Verify that all the threads are blocked
   for (size_t i = 0; i < num_threads; i++) {
     EXPECT_EQ(thread_ended[i], false);
   }
@@ -225,7 +221,7 @@ TEST(Channel, BufferedChannelCloseUnblocksReceiversTest) {
   // This should unblock all receivers
   CloseChannel(ch);
 
-  std::this_thread::sleep_for(std::chrono::milliseconds(200));  // wait
+  std::this_thread::sleep_for(std::chrono::milliseconds(100));  // wait 0.1 sec
 
   // Verify that all threads got unblocked
   for (size_t i = 0; i < num_threads; i++) {
@@ -233,13 +229,12 @@ TEST(Channel, BufferedChannelCloseUnblocksReceiversTest) {
   }
 
   for (size_t i = 0; i < num_threads; i++) t[i].join();
-  delete ch;
 }
 
-// This tests that closing a buffered channel also unblocks
-//  any senders waiting for channel to have write space
-TEST(Channel, BufferedChannelCloseUnblocksSendersTest) {
-  auto ch = MakeChannel<int>(1);
+void ChannelCloseUnblocksSendersTest(Channel<int> *ch) {
+  using paddle::framework::details::Buffered;
+  using paddle::framework::details::UnBuffered;
+
   size_t num_threads = 5;
   std::thread t[num_threads];
   bool thread_ended[num_threads];
@@ -259,34 +254,56 @@ TEST(Channel, BufferedChannelCloseUnblocksSendersTest) {
   }
   std::this_thread::sleep_for(std::chrono::milliseconds(100));  // wait
 
-  // Verify that atleast 4 threads are blocked
-  int ct = 0;
-  for (size_t i = 0; i < num_threads; i++) {
-    if (thread_ended[i] == false) ct++;
+  if (dynamic_cast<Buffered<int> *>(ch)) {
+    // If ch is Buffered, atleast 4 threads must be blocked.
+    int ct = 0;
+    for (size_t i = 0; i < num_threads; i++) {
+      if (!thread_ended[i]) ct++;
+    }
+    EXPECT_GE(ct, 4);
+  } else {
+    // If ch is UnBuffered, all the threads should be blocked.
+    for (size_t i = 0; i < num_threads; i++) {
+      EXPECT_EQ(thread_ended[i], false);
+    }
   }
-  // Atleast 4 threads must be blocked
-  EXPECT_GE(ct, 4);
-
   // Explicitly close the thread
   // This should unblock all senders
   CloseChannel(ch);
 
-  std::this_thread::sleep_for(std::chrono::milliseconds(200));  // wait
+  std::this_thread::sleep_for(std::chrono::milliseconds(100));  // wait
 
   // Verify that all threads got unblocked
   for (size_t i = 0; i < num_threads; i++) {
     EXPECT_EQ(thread_ended[i], true);
   }
 
-  // Verify that only 1 send was successful
-  ct = 0;
-  for (size_t i = 0; i < num_threads; i++) {
-    if (send_success[i]) ct++;
+  if (dynamic_cast<Buffered<int> *>(ch)) {
+    // Verify that only 1 send was successful
+    int ct = 0;
+    for (size_t i = 0; i < num_threads; i++) {
+      if (send_success[i]) ct++;
+    }
+    // Only 1 send must be successful
+    EXPECT_EQ(ct, 1);
   }
-  // Only 1 send must be successful
-  EXPECT_EQ(ct, 1);
 
   for (size_t i = 0; i < num_threads; i++) t[i].join();
+}
+
+// This tests that closing a buffered channel also unblocks
+//  any receivers waiting on the channel
+TEST(Channel, BufferedChannelCloseUnblocksReceiversTest) {
+  auto ch = MakeChannel<int>(1);
+  ChannelCloseUnblocksReceiversTest(ch);
+  delete ch;
+}
+
+// This tests that closing a buffered channel also unblocks
+//  any senders waiting for channel to have write space
+TEST(Channel, BufferedChannelCloseUnblocksSendersTest) {
+  auto ch = MakeChannel<int>(1);
+  ChannelCloseUnblocksSendersTest(ch);
   delete ch;
 }
 
@@ -294,40 +311,7 @@ TEST(Channel, BufferedChannelCloseUnblocksSendersTest) {
 //  unblocks any receivers waiting for senders
 TEST(Channel, UnbufferedChannelCloseUnblocksReceiversTest) {
   auto ch = MakeChannel<int>(0);
-  size_t num_threads = 5;
-  std::thread t[num_threads];
-  bool thread_ended[num_threads];
-
-  // Launches threads that try to read and are blocked becausew of no writers
-  for (size_t i = 0; i < num_threads; i++) {
-    thread_ended[i] = false;
-    t[i] = std::thread(
-        [&](bool *p) {
-          int data;
-          EXPECT_EQ(ch->Receive(&data), false);
-          *p = true;
-        },
-        &thread_ended[i]);
-  }
-  std::this_thread::sleep_for(std::chrono::milliseconds(500));  // wait 0.5 sec
-
-  // Verify that all the threads are blocked
-  for (size_t i = 0; i < num_threads; i++) {
-    EXPECT_EQ(thread_ended[i], false);
-  }
-
-  // Explicitly close the thread
-  // This should unblock all receivers
-  CloseChannel(ch);
-
-  std::this_thread::sleep_for(std::chrono::milliseconds(500));  // wait 0.5 sec
-
-  // Verify that all threads got unblocked
-  for (size_t i = 0; i < num_threads; i++) {
-    EXPECT_EQ(thread_ended[i], true);
-  }
-
-  for (size_t i = 0; i < num_threads; i++) t[i].join();
+  ChannelCloseUnblocksReceiversTest(ch);
   delete ch;
 }
 
@@ -335,40 +319,7 @@ TEST(Channel, UnbufferedChannelCloseUnblocksReceiversTest) {
 //  unblocks any senders waiting for senders
 TEST(Channel, UnbufferedChannelCloseUnblocksSendersTest) {
   auto ch = MakeChannel<int>(0);
-  size_t num_threads = 5;
-  std::thread t[num_threads];
-  bool thread_ended[num_threads];
-
-  // Launches threads that try to read and are blocked becausew of no writers
-  for (size_t i = 0; i < num_threads; i++) {
-    thread_ended[i] = false;
-    t[i] = std::thread(
-        [&](bool *p) {
-          int data = 10;
-          EXPECT_EQ(ch->Send(&data), false);
-          *p = true;
-        },
-        &thread_ended[i]);
-  }
-  std::this_thread::sleep_for(std::chrono::milliseconds(500));  // wait 0.5 sec
-
-  // Verify that all the threads are blocked
-  for (size_t i = 0; i < num_threads; i++) {
-    EXPECT_EQ(thread_ended[i], false);
-  }
-
-  // Explicitly close the thread
-  // This should unblock all receivers
-  CloseChannel(ch);
-
-  std::this_thread::sleep_for(std::chrono::milliseconds(500));  // wait 0.5 sec
-
-  // Verify that all threads got unblocked
-  for (size_t i = 0; i < num_threads; i++) {
-    EXPECT_EQ(thread_ended[i], true);
-  }
-
-  for (size_t i = 0; i < num_threads; i++) t[i].join();
+  ChannelCloseUnblocksReceiversTest(ch);
   delete ch;
 }
 
diff --git a/paddle/framework/details/buffered_channel.h b/paddle/framework/details/buffered_channel.h
index c6e4bec0f325ea7649021baa387b5ce9f23b4133..227a4e4811f95441158150396b5b882815fd7844 100644
--- a/paddle/framework/details/buffered_channel.h
+++ b/paddle/framework/details/buffered_channel.h
@@ -25,6 +25,14 @@ namespace paddle {
 namespace framework {
 namespace details {
 
+// Four of the properties of Buffered Channel:
+// - A send to a full channel blocks temporarily until a receive from the
+// channel or the channel is closed.
+// - A receive from an empty channel blocks temporarily until a send to the
+// channel or the channel is closed.
+// - A send to a closed channel returns false immediately.
+// - A receive from a closed channel returns false immediately.
+
 template <typename T>
 class Buffered : public paddle::framework::Channel<T> {
   friend Channel<T>* paddle::framework::MakeChannel<T>(size_t);
diff --git a/paddle/framework/details/unbuffered_channel.h b/paddle/framework/details/unbuffered_channel.h
index 92a16b4d22bbb6a8c75157444aa8474f700603fe..6b5c2196cb2991051c48f7da8397d2f479ca4c58 100644
--- a/paddle/framework/details/unbuffered_channel.h
+++ b/paddle/framework/details/unbuffered_channel.h
@@ -23,6 +23,13 @@ namespace paddle {
 namespace framework {
 namespace details {
 
+// Four of the properties of UnBuffered Channel:
+// - A send to a channel blocks temporarily until a receive from the
+// channel or the channel is closed.
+// - A receive from a channel blocks temporarily until a send to the
+// channel or the channel is closed.
+// - A send to a closed channel returns false immediately.
+// - A receive from a closed channel returns false immediately.
 template <typename T>
 class UnBuffered : public paddle::framework::Channel<T> {
   friend Channel<T>* paddle::framework::MakeChannel<T>(size_t);