try to add multiple gpu card for web service

python/paddle_serving_server_gpu/web_service.py

-# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+g  # Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -24,6 +24,10 @@ import time
 import random
 
 
+def producers(input_queue, output_queue, endpoint):
+    pass
+
+
 class WebService(object):
     def __init__(self, name="default_service"):
         self.name = name
@@ -100,6 +104,18 @@ class WebService(object):
             time.sleep(1)
         service_name = "/" + self.name + "/prediction"
 
+        input_queues = []
+        output_queue = Queue()
+        for i in range(gpu_num):
+            input_queues.append(Queue())
+
+        @app_instance.route("{}_batch".format(service_name), methods['POST'])
+        def get_prediction():
+            if not request.json:
+                abort(400)
+            if "fetch" not in request.json:
+                abort(400)
+
         @app_instance.route(service_name, methods=['POST'])
         def get_prediction():
             if not request.json: