From 26a92083941770cd6f380eef2de040f85779afbc Mon Sep 17 00:00:00 2001
From: Varun Arora <aroravarun@baidu.com>
Date: Thu, 15 Mar 2018 15:14:12 -0700
Subject: [PATCH] New PingPong test for testing channels / concurrency (#9132)

* New test for testing channels / concurrency

* Formatting fix
---
 python/paddle/fluid/tests/test_concurrency.py | 51 +++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/python/paddle/fluid/tests/test_concurrency.py b/python/paddle/fluid/tests/test_concurrency.py
index 3aa51610cd..924895a9af 100644
--- a/python/paddle/fluid/tests/test_concurrency.py
+++ b/python/paddle/fluid/tests/test_concurrency.py
@@ -217,6 +217,57 @@ class TestRoutineOp(unittest.TestCase):
             exe_result = exe.run(fetch_list=[result])
             self.assertEqual(exe_result[0][0], 34)
 
+    def test_ping_pong(self):
+        """
+        Mimics Ping Pong example: https://gobyexample.com/channel-directions
+        """
+        with framework.program_guard(framework.Program()):
+            result = self._create_tensor('return_value',
+                                         core.VarDesc.VarType.LOD_TENSOR,
+                                         core.VarDesc.VarType.FP64)
+
+            ping_result = self._create_tensor('ping_return_value',
+                                              core.VarDesc.VarType.LOD_TENSOR,
+                                              core.VarDesc.VarType.FP64)
+
+            pong_result = self._create_tensor('pong_return_value',
+                                              core.VarDesc.VarType.LOD_TENSOR,
+                                              core.VarDesc.VarType.FP64)
+
+            def ping(ch, message):
+                message_to_send_tmp = fill_constant(
+                    shape=[1], dtype=core.VarDesc.VarType.FP64, value=0)
+
+                assign(input=message, output=message_to_send_tmp)
+                fluid.channel_send(ch, message_to_send_tmp)
+
+            def pong(ch1, ch2):
+                fluid.channel_recv(ch1, ping_result)
+                assign(input=ping_result, output=pong_result)
+                fluid.channel_send(ch2, pong_result)
+
+            pings = fluid.make_channel(
+                dtype=core.VarDesc.VarType.LOD_TENSOR, capacity=1)
+            pongs = fluid.make_channel(
+                dtype=core.VarDesc.VarType.LOD_TENSOR, capacity=1)
+
+            msg = fill_constant(
+                shape=[1], dtype=core.VarDesc.VarType.FP64, value=9)
+
+            ping(pings, msg)
+            pong(pings, pongs)
+
+            fluid.channel_recv(pongs, result)
+
+            fluid.channel_close(pings)
+            fluid.channel_close(pongs)
+
+            cpu = core.CPUPlace()
+            exe = Executor(cpu)
+
+            exe_result = exe.run(fetch_list=[result])
+            self.assertEqual(exe_result[0][0], 9)
+
 
 if __name__ == '__main__':
     unittest.main()
-- 
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