[fallback] Make the get_stats timeout configurable and default to 5m (

#148)

Go test seems to fail because timeout is too short. Making it
configurable should help with the debugging. Setting it to 5m might just
fix the issue.

framework/helpers/docker.py

@@ -14,7 +14,6 @@
 
 import datetime
 import logging
-import math
 import pathlib
 import threading
 import time
@@ -260,6 +259,7 @@ def __init__(
         name: str,
         url: str,
         image: str,
+        stats_request_timeout_s: str,
     ):
         super().__init__(
             manager=manager,
@@ -278,13 +278,14 @@ def __init__(
                 }
             },
         )
+        self.stats_request_timeout_s = stats_request_timeout_s
 
     def get_stats(self, num_rpcs: int):
         logger.debug("Sending %d requests", num_rpcs)
         stub = test_pb2_grpc.LoadBalancerStatsServiceStub(self.channel())
         res = stub.GetClientStats(
             messages_pb2.LoadBalancerStatsRequest(
-                num_rpcs=num_rpcs, timeout_sec=math.ceil(num_rpcs * 10)
+                num_rpcs=num_rpcs, timeout_sec=self.stats_request_timeout_s
             )
         )
         return res

tests/fallback_test.py

@@ -49,7 +49,11 @@
 _STATUS_POLL_INTERVAL_MS = flags.DEFINE_integer(
     "status_poll_interval_ms", 300, "Channel status poll interval (in ms)"
 )
-
+_STATS_REQUEST_TIMEOUT_S = flags.DEFINE_integer(
+    "stats_request_timeout_s",
+    300,
+    "Number of seconds the client will wait for the requested number of RPCs",
+)
 _LISTENER = "listener_0"
 
 absl.flags.adopt_module_key_flags(framework.xds_k8s_testcase)
@@ -92,6 +96,7 @@ def start_client(self, port: int = None, name: str = None):
             port=port or get_free_port(),
             url=f"xds:///{_LISTENER}",
             image=framework.xds_k8s_flags.CLIENT_IMAGE.value,
+            stats_request_timeout_s=_STATS_REQUEST_TIMEOUT_S.value,
         )
 
     def start_control_plane(