AbstractConnection.register_connect_callback is semi-private in redis-py 5.0.1

[rohangreddy]

The following changes were made to AbstractConnection in redis-py 5.0.1, as described here

# redis-py 5.0.0

class AbstractConnection:
    def register_connect_callback(self, callback):

# redis-py 5.0.1

class AbstractConnection:
    def _register_connect_callback(self, callback):

register_connect_callback is used by the celery result backend here and may cause issues due to the change.

I'm not sure if any action is necessary since a fix seems to be open, but wanted to raise awareness for those who are using redis-py > 5.0.0

[auvipy]

thanks for the report!

[Shineaki]

Thanks for this post, I just ran into this bug and wasn't sure what to make of it:

Exception ignored in: <function AsyncResult.__del__ at 0x7f7222a3b9d0> Traceback (most recent call last): File "/usr/local/lib/python3.9/site-packages/celery/result.py", line 417, in __del__ self.backend.remove_pending_result(self) File "/usr/local/lib/python3.9/site-packages/celery/backends/asynchronous.py", line 208, in remove_pending_result self.on_result_fulfilled(result) File "/usr/local/lib/python3.9/site-packages/celery/backends/asynchronous.py", line 216, in on_result_fulfilled self.result_consumer.cancel_for(result.id) File "/usr/local/lib/python3.9/site-packages/celery/backends/redis.py", line 184, in cancel_for self._pubsub.unsubscribe(key) File "/usr/local/lib/python3.9/contextlib.py", line 137, in __exit__ self.gen.throw(typ, value, traceback) File "/usr/local/lib/python3.9/site-packages/celery/backends/redis.py", line 130, in reconnect_on_error self._ensure(self._reconnect_pubsub, ()) File "/usr/local/lib/python3.9/site-packages/celery/backends/redis.py", line 384, in ensure return retry_over_time( File "/usr/local/lib/python3.9/site-packages/kombu/utils/functional.py", line 318, in retry_over_time return fun(*args, **kwargs) File "/usr/local/lib/python3.9/site-packages/celery/backends/redis.py", line 122, in _reconnect_pubsub self._pubsub.connection.register_connect_callback(self._pubsub.on_connect) AttributeError: 'SSLConnection' object has no attribute 'register_connect_callback'

• Redis = 5.0.1
• Celery = 5.3.6

[MuhammadHadiofficial]

I faced the same issue as well. It works for a while and fails.
Here are the logs

2023-12-08 18:51:32.182
AttributeError: 'SSLConnection' object has no attribute 'register_connect_callback'
2023-12-08 18:51:32.182
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2023-12-08 18:51:32.182
self._pubsub.connection.register_connect_callback(self._pubsub.on_connect)
2023-12-08 18:51:32.182
File "/usr/local/lib/python3.11/site-packages/celery/backends/[redis.py](http://redis.py/)", line 122, in _reconnect_pubsub
2023-12-08 18:51:32.182
^^^^^^^^^^^^^^^^^^^^
2023-12-08 18:51:32.182
return fun(*args, **kwargs)
2023-12-08 18:51:32.182
File "/usr/local/lib/python3.11/site-packages/kombu/utils/[functional.py](http://functional.py/)", line 318, in retry_over_time
2023-12-08 18:51:32.182
^^^^^^^^^^^^^^^^
2023-12-08 18:51:32.182
return retry_over_time(
2023-12-08 18:51:32.181
File "/usr/local/lib/python3.11/site-packages/celery/backends/[redis.py](http://redis.py/)", line 384, in ensure
2023-12-08 18:51:32.181
self._ensure(self._reconnect_pubsub, ())
2023-12-08 18:51:32.181
File "/usr/local/lib/python3.11/site-packages/celery/backends/[redis.py](http://redis.py/)", line 130, in reconnect_on_error
2023-12-08 18:51:32.181
self.gen.throw(typ, value, traceback)
2023-12-08 18:51:32.181
File "/usr/local/lib/python3.11/[contextlib.py](http://contextlib.py/)", line 155, in exit
2023-12-08 18:51:32.181
with self.reconnect_on_error():
2023-12-08 18:51:32.181
File "/usr/local/lib/python3.11/site-packages/celery/backends/[redis.py](http://redis.py/)", line 183, in cancel_for
2023-12-08 18:51:32.181
self.result_consumer.cancel_for([result.id](http://result.id/))
2023-12-08 18:51:32.181
File "/usr/local/lib/python3.11/site-packages/celery/backends/[asynchronous.py](http://asynchronous.py/)", line 216, in on_result_fulfilled
2023-12-08 18:51:32.181
self.on_result_fulfilled(result)
2023-12-08 18:51:32.180
File "/usr/local/lib/python3.11/site-packages/celery/backends/[asynchronous.py](http://asynchronous.py/)", line 208, in remove_pending_result
2023-12-08 18:51:32.180
self.backend.remove_pending_result(self)
2023-12-08 18:51:32.179
File "/usr/local/lib/python3.11/site-packages/celery/[result.py](http://result.py/)", line 417, in del
2023-12-08 18:51:32.179
Traceback (most recent call last):
2023-12-08 18:51:32.179
Exception ignored in: <function AsyncResult.del at 0x7f5c043198a0>
2023-12-08 18:51:32.156
" this error happened we don't get the response.

redis = "^5.0.1"
celery = "^5.3.5"

[rohangreddy]

Hey @MuhammadHadiofficial @Shineaki, can you try downgrading to redis 5.0.0?

I think there is a minor incompatibility with the latest versions of redis. As I described in the original post, redis 5.0.1+ had a change that made the register_callback_connection method of the AbstractConnection class private:

register_callback_connection -> _register_callback_connection

So when Celery tries to access register_connect_callback in redis 5.0.1+, it makes sense that you are seeing AttributeError: 'SSLConnection' object has no attribute 'register_connect_callback' since that method is now private.

[rohangreddy]

The maintainers of redis-py have a fix open that reverts this back to a public method, but it hasn't been merged yet. So a band-aid solution of downgrading to redis-py < 5.0.1 should work for now 😄

[MuhammadHadiofficial]

@rohangreddy Thanks! I did downgrade last night and it worked 🚀