add cuda check for gpu server

python/paddle_serving_server_gpu/__init__.py

@@ -116,6 +116,7 @@ class Server(object):
         self.reload_interval_s = 10
         self.module_path = os.path.dirname(paddle_serving_server.__file__)
         self.cur_path = os.getcwd()
+        self.check_cuda
         self.use_local_bin = False
         self.gpuid = 0
 
@@ -142,6 +143,13 @@ class Server(object):
             self.use_local_bin = True
             self.bin_path = os.environ["SERVING_BIN"]
 
+    def check_cuda(self):
+        r = os.system("whereis cuda")
+        if r != 0:
+            raise SystemExit(
+                "CUDA not found, please check your environment or use cpu version by \"pip install paddle_serving_server\""
+            )
+
     def set_gpuid(self, gpuid=0):
         self.gpuid = gpuid