Django Nginx Gunicorn = 504 Timeout

Question

I'm trying to publish a Django application on the production server using Nginx + Gunicorn. When I doing a simple stress test on the server (holding the F5 key for a minute) the server returns a 504 Gateway Time-out error. Why does this happen? This error only appears for the user when doing multiple concurrent requests, or the system will be fully unavailable to everyone?

Answer 1

When you hold down F5:

• You've started hundreds of requests.
• Those requests have filled your gunicorn request queue.
• The request handlers have not been culled as soon as the connection drops.
• Your latest requests are stuck in the queue behind all the previous requests.
• Nginx times out.
• For everyone.

Solutions:

• Set up rate-limiting buckets in Nginx, keyed on IP, such that one malicious user can't spam you with requests and DOS your site.
• Set up a global rate-limiting bucket in Nginx such that you don't overfill your request queue.
• Make Nginx serve a nice "Reddit is under heavy load" style page, so users know that this is a purposeful event

Or:

Replace gunicorn with uwsgi. It's faster, more memory efficient, integrates smoothly with nginx, and most importantly: It will kill the request handler immediately if the connection drops, such that F5 spam can't kill your server.