diff --git a/gnes/service/frontend.py b/gnes/service/frontend.py
index 02b5d812..2775a082 100644
--- a/gnes/service/frontend.py
+++ b/gnes/service/frontend.py
@@ -142,10 +142,18 @@ def StreamCall(self, request_iterator, context):
                     zmq_client.send_message(self.add_envelope(request, zmq_client), self.args.timeout)
                     num_request += 1
 
-                    while True:
+                    while num_request > 10:
                         try:
                             # fetch response in real time to reduce network overload
-                            msg = zmq_client.recv_message(10)
+                            timeout = 50
+                            if self.args.timeout > 0:
+                                timeout = min(0.5 * self.args.timeout, 100)
+
+                            # only 1000 pending tasks are approved
+                            if num_request > 1000:
+                                timeout = -1
+
+                            msg = zmq_client.recv_message(timeout)
                             yield self.remove_envelope(msg)
                             num_request -= 1
                         except TimeoutError: