Warmup django application during uwsgi chain-raload

Question

I'm using uwsgi + django and trying to make the fastest reloading. I've configured chain reloading (http://uwsgi-docs.readthedocs.io/en/latest/articles/TheArtOfGracefulReloading.html#chain-reloading-lazy-apps), but still there are couple seconds of latency while serving first request after worker reload.

Is there any way to warm up the django application with uwsgi configuration to reduce waiting time?

Answer 1

In the cited article, there is an special recommendation for Django and so apps: http://uwsgi-docs.readthedocs.io/en/latest/articles/TheArtOfGracefulReloading.html#dealing-with-ultra-lazy-apps-like-django

On some of my projects, there are a /warmup/ URL that loads everything that can be loaded upfront. The uWSGI does give client requests to the worker only after the whole wsgi.py of the project ran, so we do a fake call the /warmup/ url BEFORE the uWSGI tried to serve any real client requests:

# /django-project-root/wsgi.py
import sys
from django.core.wsgi import get_wsgi_application

application = get_wsgi_application()
(...)

# Django warm-up ahead of time instead of lazy
# From: http://uwsgi-docs.readthedocs.org/en/latest/articles/TheArtOfGracefulReloading.html#dealing-with-ultra-lazy-apps-like-django
#  And: https://github.com/stefantalpalaru/uwsgi_reload/blob/master/examples/wsgi.py#L19
application({
    'REQUEST_METHOD': 'GET',
    'SERVER_NAME': '127.0.0.1',
    'SERVER_PORT': 80,
    'PATH_INFO': '/warmup/',
    'wsgi.input': sys.stdin,
}, lambda x, y: None)

Please mind that if your uwsgi.ini configures lazy-apps=true then the process load will trigger only on client requests, so it will warmup only in case of an harakiri. Otherwise it will warmup fine.