[ducdetronquito]

You're right, but I also don't find a way a task queue library could know that upfront either to implement progress reporting.

Does anyone know a task queue library that implement it ? I would be curious to look at it !

[amanzi]

The way it's typically done is that the worker process reports back its progress to the job metadata on the queue, and the web worker polls the job metadata to read the progress. I've implemented this for progress bars many times on Django with django-rq.

I first learned about it from Miguel Grinberg's Flask tutorial: https://blog.miguelgrinberg.com/post/the-flask-mega-tutorial... But the same concept applies to Django.