Deadlock condition in graphclient on subscribe/unsubscribe

[monaresh]

Found a deadlock condition when trying to unsubscribe using the client

1. Main thread enters UnsubscribeGraphAPI -> acquires self._subscriptionLock
2. Main thread calls self._backgroundThread.RunCoroutine(_Unsubscribe()).result() - still holding _subscriptionLock.

.result() blocks the main thread until the coroutine returns -> we are waiting for this under lock
3. On the background thread's event loop, _Unsubscribe runs and reaches await self._CloseWebSocket() -> await self._webSocket.close(). That await yields control back to the event loop.
4. now yielded, the sleeping _ListenToWebSocket function wakes up because the websocket just

5. _ListenToWebSocket exception handler executes with self._subscriptionLock: - synchronous threading.Lock. The main thread holds it, so the background thread blocks here and freezes. The entire event loop is now blocked - no further awaits can move now

6. _Unsubscribe await self._webSocket.close() never gets to return, so .result() on the main thread never completes. Main thread keeps holding _subscriptionLock. Stuck.

Error on sigterm

2026-05-08 14:14:48,914 mujinwebstackclient.controllerwebclientraw [ERROR] [controllerwebclientraw.py:598 _ListenToWebSocket] caught WebSocket exception: sent 1000 (OK); no close frame received
Traceback (most recent call last):
 File "/opt/lib/python3.13/site-packages/mujinwebstackclient/controllerwebclientraw.py", line 539, in _ListenToWebSocket
   async for response in self._webSocket:
   ...<55 lines>...
           subscription.GetSubscriptionCallbackFunction()(error=None, response=content.get('payload') or {})
 File "/opt/lib/python3.13/site-packages/websockets/asyncio/connection.py", line 242, in __aiter__
   yield await self.recv()
         ^^^^^^^^^^^^^^^^^
 File "/opt/lib/python3.13/site-packages/websockets/asyncio/connection.py", line 322, in recv
   raise self.protocol.close_exc from self.recv_exc
websockets.exceptions.ConnectionClosedError: sent 1000 (OK); no close frame received
ConnectionClosedError(None, Close(code=1000, reason=''), None)
                        

[woswos]

Pipeline #1903871