Memory issue when sharing CancelToken between posts for IO implementation about dio

[kuhnroyal]

I tried to enable the new leak tracking but didn't get very far yet...

[AlexV525]

Could you attach the minimal reproducible example and some analysis graphs or details?

[zambetpentru]

We have noticed an Out of Memory error as well, on iOS since 5.4.x.

Our issue was casting the .get to <List> unnecessarily even though it supports Uint8List.

[AlexV525]

@kuhnroyal I have been thinking about the cause of this issue for the last few days, it could be caused by referencing the resources of the request in callers like .whenComplete so they will only get released once the CancelToken canceled, but it doesn't, so memory leaks. Any ideas?

[AlexV525]

If yes, we might add a global map to cache the necessary instances for the corresponding cancel token.

[kunstmusik]

@AlexV525 I haven't had time to followup, but yes, as mentioned in my first message, we found that the .whenComplete callback captures over the Request:

      if (cancelFuture != null) {
        cancelFuture.whenComplete(() => request.abort());
      }

and whenComplete() also adds additional handlers each time it is called. So if a CancelToken is passed in to multiple fetches, it will keep accruing whenComplete handlers that all capture over individual requests.

[AlexV525]

@kunstmusik Can you verify if #2252 fixes the issue?