Internal refactoring.

PiperOrigin-RevId: 235271388

Author: rchao

tensorflow/contrib/distribute/python/multi_worker_test_base.py

@@ -37,12 +37,16 @@
 from tensorflow.core.protobuf import config_pb2
 from tensorflow.core.protobuf import rewriter_config_pb2
 from tensorflow.python.client import session
+from tensorflow.python.distribute import distribute_coordinator as dc
 from tensorflow.python.estimator import run_config
 from tensorflow.python.platform import test
 from tensorflow.python.platform import tf_logging as logging
 from tensorflow.python.training import coordinator
 from tensorflow.python.training import server_lib
 
+
+original_run_std_server = dc._run_std_server  # pylint: disable=protected-access
+
 ASSIGNED_PORTS = set()
 lock = threading.Lock()
 
@@ -357,6 +361,22 @@ def __len__(self):
 class IndependentWorkerTestBase(test.TestCase):
   """Testing infra for independent workers."""
 
+  def _make_mock_run_std_server(self):
+    thread_local = threading.local()
+
+    def _mock_run_std_server(*args, **kwargs):
+      ret = original_run_std_server(*args, **kwargs)
+      # Wait for all std servers to be brought up in order to reduce the chance
+      # of remote sessions taking local ports that have been assigned to std
+      # servers. Only call this barrier the first time this function is run for
+      # each thread.
+      if not getattr(thread_local, 'server_started', False):
+        self._barrier.wait()
+      thread_local.server_started = True
+      return ret
+
+    return _mock_run_std_server
+
   def setUp(self):
     self._mock_os_env = MockOsEnv()
     self._mock_context = test.mock.patch.object(os, 'environ',