Merge pull request #22860 from lidizheng/fix-metadata-flags-test-flake

Fix the metadata flags test flake

src/python/grpcio_tests/tests/unit/_metadata_flags_test.py

@@ -17,6 +17,7 @@ import time
 import weakref
 import unittest
 import threading
+import logging
 import socket
 from six.moves import queue
 
@@ -25,7 +26,7 @@ import grpc
 from tests.unit import test_common
 from tests.unit.framework.common import test_constants
 import tests.unit.framework.common
-from tests.unit.framework.common import bound_socket
+from tests.unit.framework.common import get_socket
 
 _UNARY_UNARY = '/test/UnaryUnary'
 _UNARY_STREAM = '/test/UnaryStream'
@@ -101,8 +102,9 @@ class _GenericHandler(grpc.GenericRpcHandler):
 
 def create_dummy_channel():
     """Creating dummy channels is a workaround for retries"""
-    with bound_socket() as (host, port):
-        return grpc.insecure_channel('{}:{}'.format(host, port))
+    host, port, sock = get_socket()
+    sock.close()
+    return grpc.insecure_channel('{}:{}'.format(host, port))
 
 
 def perform_unary_unary_call(channel, wait_for_ready=None):
@@ -203,51 +205,56 @@ class MetadataFlagsTest(unittest.TestCase):
         #   main thread. So, it need another method to store the
         #   exceptions and raise them again in main thread.
         unhandled_exceptions = queue.Queue()
-        with bound_socket(listen=False) as (host, port):
-            addr = '{}:{}'.format(host, port)
-            wg = test_common.WaitGroup(len(_ALL_CALL_CASES))
 
-            def wait_for_transient_failure(channel_connectivity):
-                if channel_connectivity == grpc.ChannelConnectivity.TRANSIENT_FAILURE:
+        # We just need an unused TCP port
+        host, port, sock = get_socket()
+        sock.close()
+
+        addr = '{}:{}'.format(host, port)
+        wg = test_common.WaitGroup(len(_ALL_CALL_CASES))
+
+        def wait_for_transient_failure(channel_connectivity):
+            if channel_connectivity == grpc.ChannelConnectivity.TRANSIENT_FAILURE:
+                wg.done()
+
+        def test_call(perform_call):
+            with grpc.insecure_channel(addr) as channel:
+                try:
+                    channel.subscribe(wait_for_transient_failure)
+                    perform_call(channel, wait_for_ready=True)
+                except BaseException as e:  # pylint: disable=broad-except
+                    # If the call failed, the thread would be destroyed. The
+                    # channel object can be collected before calling the
+                    # callback, which will result in a deadlock.
                     wg.done()
+                    unhandled_exceptions.put(e, True)
 
-            def test_call(perform_call):
-                with grpc.insecure_channel(addr) as channel:
-                    try:
-                        channel.subscribe(wait_for_transient_failure)
-                        perform_call(channel, wait_for_ready=True)
-                    except BaseException as e:  # pylint: disable=broad-except
-                        # If the call failed, the thread would be destroyed. The
-                        # channel object can be collected before calling the
-                        # callback, which will result in a deadlock.
-                        wg.done()
-                        unhandled_exceptions.put(e, True)
-
-            test_threads = []
-            for perform_call in _ALL_CALL_CASES:
-                test_thread = threading.Thread(target=test_call,
-                                               args=(perform_call,))
-                test_thread.exception = None
-                test_thread.start()
-                test_threads.append(test_thread)
-
-            # Start the server after the connections are waiting
-            wg.wait()
-            server = test_common.test_server(reuse_port=True)
-            server.add_generic_rpc_handlers(
-                (_GenericHandler(weakref.proxy(self)),))
-            server.add_insecure_port(addr)
-            server.start()
-
-            for test_thread in test_threads:
-                test_thread.join()
-
-            # Stop the server to make test end properly
-            server.stop(0)
-
-            if not unhandled_exceptions.empty():
-                raise unhandled_exceptions.get(True)
+        test_threads = []
+        for perform_call in _ALL_CALL_CASES:
+            test_thread = threading.Thread(target=test_call,
+                                           args=(perform_call,))
+            test_thread.daemon = True
+            test_thread.exception = None
+            test_thread.start()
+            test_threads.append(test_thread)
+
+        # Start the server after the connections are waiting
+        wg.wait()
+        server = test_common.test_server(reuse_port=True)
+        server.add_generic_rpc_handlers((_GenericHandler(weakref.proxy(self)),))
+        server.add_insecure_port(addr)
+        server.start()
+
+        for test_thread in test_threads:
+            test_thread.join()
+
+        # Stop the server to make test end properly
+        server.stop(0)
+
+        if not unhandled_exceptions.empty():
+            raise unhandled_exceptions.get(True)
 
 
 if __name__ == '__main__':
+    logging.basicConfig(level=logging.DEBUG)
     unittest.main(verbosity=2)