Change websocket cleanup performance from O(n^2) to O(n). #429
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Move subscription tracking to a dict keyed by the underlying websocket object. Changes the cleanup from two nested for loops (the 2nd being the unsubscribe_from method), to a single loop with (the common case) deleting a single key from a dict.
savingoyal
approved these changes
Jun 17, 2024
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lgtm! we can ship this once @saikonen approves |
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@savingoyal @saikonen is there any update here, anything I can do to help get this upstreamed? thanks! |
saikonen
reviewed
Aug 23, 2024
| # This is primarily useful when calling `unsubscribe_from` during the cleanup | ||
| # loop in the event handler. | ||
| for k in list(self._subscriptions.keys()): | ||
| for sub in self._subscriptions[k]: |
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note to self: no KeyError possible due to self._subscriptions being a defaultdict(list)
| self.subscriptions = list( | ||
| filter(lambda s: uuid != s.uuid or ws != s.ws, self.subscriptions)) | ||
| self._subscriptions[ws] = list( | ||
| filter(lambda s: uuid != s.uuid or ws != s.ws, self._subscriptions[ws])) |
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is the ws != s.ws check necessary anymore as the subscription is keyed per websocket?
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Move subscription tracking to a dict keyed by the underlying websocket object.
Changes the cleanup from two nested for loops (the 2nd being the unsubscribe_from method), to a single loop with (the common case) deleting a single key from a dict.
We found that with a sufficient number of disconnected clients, and long gaps between database activity, the cleanup could end up taking multiple hours. This would cause the python web service to become unresponsive.