fix: stop event loop on Connector.close (#410)

Author: jackwotherspoon

google/cloud/sql/connector/connector.py

@@ -284,6 +284,12 @@ def close(self) -> None:
         )
         # Will attempt to safely shut down tasks for 5s
         close_future.result(timeout=5)
+        # if background thread exists for Connector, clean it up
+        if self._thread:
+            # stop event loop running in background thread
+            self._loop.call_soon_threadsafe(self._loop.stop)
+            # wait for thread to finish closing (i.e. loop to stop)
+            self._thread.join()
 
     async def close_async(self) -> None:
         """Helper function to cancel Instances' tasks

tests/unit/test_connector.py

@@ -87,7 +87,6 @@ def test_connect_with_unsupported_driver(connector: Connector) -> None:
         )
     # assert custom error message for unsupported driver is present
     assert exc_info.value.args[0] == "Driver 'bad_driver' is not supported."
-    connector.close()
 
 
 @pytest.mark.asyncio
@@ -157,3 +156,14 @@ async def test_create_async_connector() -> None:
     connector = await create_async_connector()
     assert connector._loop == asyncio.get_running_loop()
     await connector.close_async()
+
+
+def test_Connector_close_kills_thread() -> None:
+    """Test that Connector.close kills background threads."""
+    # open and close Connector object
+    connector = Connector()
+    # verify background thread exists
+    assert connector._thread
+    connector.close()
+    # check that connector thread is no longer running
+    assert connector._thread.is_alive() is False