Celeryd and concurrency why only one works?

Question

Python

I start celeryd multi with --concurrency 3 enabled, it's not entirely clear due to the forgiveness of time or when some condition occurs, but after a while two workers stop working and only one works.
All the methods described in the documentation have been tried, including enabling options for long tasks, this and -0fair, and even working through 3 independent celery workers as 3 separate processes.