active_queues as set in redis transport does not maintain order

[chadawagner]

https://github.com/celery/kombu/blob/488ed977e0345eb0f509f020a80bb88f42bb1315/kombu/transport/redis.py#L986-L989

When using the "priority" scheduling cycle with the redis transport, the original order of the list of queues to use is not preserved, due to _active_queues being converted from a list to a set and back again.

Is there a reason the active_queues property needs to be a set? As far as I can tell, it's only used to check if it's empty, check its length, and to update the queue cycle. Could we change it to just return a list instead? Or if duplicates are an issue, remove them while preserving order?

[auvipy]

did you find any solution? up for a PR?

[chadawagner]

@auvipy I just monkeypatched that active_queues method to return a list rather than a set. Solved my problem but it could be a breaking change if anyone were doing something with the output of that method besides just iterating or checking length, or if the method is expected to remove duplicates.