pykka hack in old code no longer works

[natumbri]

@jodal

The old code in mopidy-youtube includes the following hack:

            # # What was this for?  Whatever it was for, it doesn't work
            # # for pykka v4.3 onwards, since ThreadingFuture uses 
            # # a condition variable instead of a queue
            if not future._queue.empty():  # hack, no public is_set()
                continue

mopidy-youtube/mopidy_youtube/youtube.py

Line 160 in 023beee

# if not future._queue.empty(): # hack, no public is_set()

It no longer works with the current version of pykka because Queue.queue is no longer used in ThreadingFuture. The code doesn't function correctly without it. Would somebody be able to explain what the old code was doing, and what a sensible replacement might be?

Cheers,
Nik

[jodal]

I've never seen this code before 😅

It looks like it used future._queue.empty() to check if a future was already set to avoid redoing work to transform the data that it later sets as the future's value.

I can think of a couple of ways forward:

• Add something to the object to keep track of the field being set or not. E.g. there is already the property foo and the future value _foo, then one could add a bool _foo_is_set to keep track of this.
• Do the transformation work anyway, and just wrap the future.set() call in a try: ... except queue.Full: ... to not crash if trying to set a future twice. ThreadingActor still raises queue.Full if trying to set it twice, to keep the original public API.

[jagjordi]

Having a similar error:

WARNING  2025-09-28 20:45:53,874 [6:ThreadPoolExecutor-0_0] mopidy_youtube
  Error 'ThreadingFuture' object has no attribute '_queue' setting api data for hu9q49gBwVU; probably private or deleted

running v2025.09.26 in an Alpine (edge) container
When sending a yt video to Mopidy, it "freezes"/hangs and nothing else can be played anymore

[jagjordi]

Is there any easy way to fix this? I have limited knowledge and experience but I can try to help

[marcosdvpereira]

music-assistant/server#2636 related?