PYTHON-2285 Only start kill cursors background thread if/when the client connects to the MongoDB deployment

Author: prashantmital

pymongo/mongo_client.py

@@ -719,8 +719,6 @@ def __init__(
             direct_connection=options.direct_connection)
 
         self._topology = Topology(self._topology_settings)
-        if connect:
-            self._topology.open()
 
         def target():
             client = self_ref()
@@ -739,7 +737,9 @@ def target():
         # this closure. When the client is freed, stop the executor soon.
         self_ref = weakref.ref(self, executor.close)
         self._kill_cursors_executor = executor
-        executor.open()
+
+        if connect:
+            self._get_topology()
 
         self._encrypter = None
         if self.__options.auto_encryption_opts:

test/test_client.py

@@ -790,6 +790,24 @@ def test_close_stops_kill_cursors_thread(self):
         client.close()
         self.assertTrue(client._kill_cursors_executor._stopped)
 
+    def test_uri_connect_option(self):
+        # Ensure that topology is not opened if connect=False.
+        client = rs_client(connect=False)
+        self.assertFalse(client._topology._opened)
+
+        # Ensure kill cursors thread has not been started.
+        kc_thread = client._kill_cursors_executor._thread
+        self.assertFalse(kc_thread and kc_thread.is_alive())
+
+        # Using the client should open topology and start the thread.
+        client.admin.command('isMaster')
+        self.assertTrue(client._topology._opened)
+        kc_thread = client._kill_cursors_executor._thread
+        self.assertTrue(kc_thread and kc_thread.is_alive())
+
+        # Tear down.
+        client.close()
+
     def test_close_does_not_open_servers(self):
         client = rs_client(connect=False)
         topology = client._topology