fix: await cancelled subscription tasks on ws shutdown

RELEASE.md

@@ -0,0 +1,3 @@
+Release type: patch
+
+Await cancelled subscription tasks during WebSocket shutdown so their `finally` blocks run before shared state (DB pools, event loop) is torn down.

strawberry/subscriptions/protocols/graphql_transport_ws/handlers.py

@@ -92,9 +92,17 @@ async def shutdown(self) -> None:
             with suppress(asyncio.CancelledError):
                 await self.connection_init_timeout_task
 
+        cancelled_tasks: list[asyncio.Task] = []
         for operation_id in list(self.operations.keys()):
+            op = self.operations[operation_id]
+            if op.task:
+                cancelled_tasks.append(op.task)
             await self.cleanup_operation(operation_id)
+
         await self.reap_completed_tasks()
+        # cleanup_operation cancels but does not await tasks (would block
+        # the message loop). Safe to await here — no more messages to process.
+        await asyncio.gather(*cancelled_tasks, return_exceptions=True)
 
     def on_request_accepted(self) -> None:
         # handle_request should call this once it has sent the

tests/websockets/test_graphql_transport_ws.py

@@ -1216,3 +1216,54 @@ async def test_unexpected_client_disconnects_are_gracefully_handled(
 
         assert not process_errors.called
         assert Subscription.active_infinity_subscriptions == 0
+
+
+async def test_shutdown_awaits_cancelled_subscription_tasks(
+    http_client: HttpClient,
+):
+    with contextlib.suppress(ImportError):
+        from tests.http.clients.channels import ChannelsHttpClient
+
+        if isinstance(http_client, ChannelsHttpClient):
+            pytest.skip("Can't patch on_init for this client")
+
+    handler = None
+    cleanup_done_at_shutdown_end = None
+
+    def on_init(_handler):
+        nonlocal handler
+        if handler:
+            return
+        handler = _handler
+        original_shutdown = _handler.shutdown
+
+        async def tracked_shutdown():
+            nonlocal cleanup_done_at_shutdown_end
+            await original_shutdown()
+            cleanup_done_at_shutdown_end = Subscription.active_infinity_subscriptions
+
+        _handler.shutdown = tracked_shutdown
+
+    with patch.object(DebuggableGraphQLTransportWSHandler, "on_init", on_init):
+        async with http_client.ws_connect(
+            "/graphql", protocols=[GRAPHQL_TRANSPORT_WS_PROTOCOL]
+        ) as ws:
+            await ws.send_message({"type": "connection_init"})
+            ack: ConnectionAckMessage = await ws.receive_json()
+            assert ack == {"type": "connection_ack"}
+
+            await ws.send_message(
+                {
+                    "id": "sub1",
+                    "type": "subscribe",
+                    "payload": {"query": 'subscription { infinity(message: "Hi") }'},
+                }
+            )
+            await ws.receive(timeout=2)
+            assert Subscription.active_infinity_subscriptions == 1
+
+            await ws.close()
+
+    await asyncio.sleep(0.5)
+    assert handler is not None
+    assert cleanup_done_at_shutdown_end == 0