Using gunicorn w/ gevent, requests hang and workers throw [CRITICAL] WORKER TIMEOUT

[Akshar Dave]

When in the Google App Engine (flexible) environment, The request hangs and times out after 120 secs ... In the logs, I am getting [CRITICAL] WORKER TIMEOUT (pid:277) error when serving the Flask app with gunicorn and gevent workers. 

here is app.yaml:

runtime: python

env: flex

entrypoint: gunicorn -c gunicorn.conf.py -b :$PORT main:app

runtime_config:

    python_version: 3 

threadsafe: false

# This sample incurs costs to run on the App Engine flexible environment.

# The settings below are to reduce costs during testing and are not appropriate

# for production use. For more information, see:

# https://cloud.google.com/appengine/docs/flexible/python/configuring-your-app-with-app-yaml

automatic_scaling:

  min_num_instances: 5

  max_num_instances: 40

  cool_down_period_sec: 180

  cpu_utilization:

    target_utilization: 0.85

resources:

  cpu: 80

  memory_gb: 80

  disk_size_gb: 10

here is gunicorn.conf.py: 

import multiprocessing

workers = multiprocessing.cpu_count() * 2 + 1

keepalive = 120

timeout = 120

worker_class = 'gevent'

worker_connections = 1000

loglevel = 'debug'

here is requirements.txt:

Flask==1.0.3

gevent==1.4.0

gunicorn==19.9.0

google-cloud-bigtable

google-cloud-happybase

locustio==0.11.0

pyzmq==18.1.0

[Yasser Karout]

I suggest trying to increase the timeout in the app.yaml to see if you can get requests to succeed if the timeouts are longer. If the requests succeed, the issue might be the code of the application, or you need more resources for it.