Gunicorn worker timeout error

Question

I have setup gunicorn with 3 workers 30 worker connections and using eventlet worker class. It is setup behind Nginx. After every few requests, I see this in the logs.

Answer 1

I've got the same problem in Docker.

In Docker I keep trained LightGBM model + Flask serving requests. As HTTP server I used gunicorn 19.9.0. When I run my code locally on my Mac laptop everything worked just perfect, but when I ran the app in Docker my POST JSON requests were freezing for some time, then gunicorn worker had been failing with [CRITICAL] WORKER TIMEOUT exception.

I tried tons of different approaches, but the only one solved my issue was adding worker_class=gthread.

Here is my complete config:

import multiprocessing

workers = multiprocessing.cpu_count() * 2 + 1
accesslog = "-" # STDOUT
access_log_format = '%(h)s %(l)s %(u)s %(t)s "%(r)s" %(s)s %(b)s "%(q)s" "%(D)s"'
bind = "0.0.0.0:5000"
keepalive = 120
timeout = 120
worker_class = "gthread"
threads = 3