celery worker cannot start

[Mifan-Ren]

hi,
When I tried ottertune followed wiki, it was stuck in step: python celery worker --loglevel=info --pool=threads . The debug info is "celery.bootsteps: 272 worker: hub register pool".
Similarly, when l tried fake data test followed wiki "quickly get started", the website didn't have any knobs to be tuned. My guess is that the knob information is not being used, but the table in ottertune for server mysql website_knobcatalog and website_metriccatalog are not empty.
My target DBMS is postgresql-9.6, and I’m confused whats the problem. Thanks.