andrew-chen-wang / django_31_async_to_sync

Testing Django Async Views with Django ORM wrapped in async_to_sync

Django 3.1 Async Views Testing with Django ORM

By: Andrew Chen Wang

Created on: 10 September 2020 midnight for some reason...

TL;DR Don't use async views until an async database package is made and Django incorporates it into its ORM. Use completely sync views since those middlewares are still sync. Context switching will degrade your server's performance; using sync views will maintain your server's performance.

Abstract

We all know that the Django ORM is crazy easy to use. It's also integral in almost every web application, specifically those using a database. With Django 3.1 coming out, I wanted to see what I could do to increase the performance of my current applications. However, I will not be testing websockets; they are by far the most efficient and some would say secure (as the only attack method is improper authentication into a socket and cross-site session cookiejacking) as the number of requests to authenticate goes from several (HTTP requests) to just one.

Before we begin, please check out psycopg3 to allow the Django ORM to be more async capable without needing to use the primary thing I'll be using for this test. Also, please read the Django docs on the performance gain (and even degradation!) when mixing a/sync views, middleware, and other functionalities like context switching using asgiref for database or cache operations.

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Tools

I'm running Python 3.8 on a core i5 on a Macbook Air with 16GB of RAM.

I'll be using psycopg2, Django 3.1 (which allows for async views), and locust, a load testing tool that is going to crash my computer :) To be as efficient as possible, I'll be using simple HTTP connections and using a proper DEBUG=False production environment using Gunicorn for my WSGI server and Uvicorn workers for my ASGI server (Uvicorn replaces Gunicorn's worker but sits on top of Uvicorn's framework).

I'll also be using miscellaneous views which will test redis-py vs. aioredis vs. using asgiref.sync_to_async according to their environments (a/sync). The tests won't be as sophisticated as the benchmarks that someone made for the two (and some other Pythonic cachers).

Methodology

For each, I'll be using my localhost and then my Raspberry Pi 3 to simulate "latency."

The Django views being implemented:

1. A generic class based TemplateView (and also a function based because why not) with nothing but a bit of text and some other scripts from CDNs.
2. A function view (using ORM) for getting an object.
3. A function view (using ORM) for posting a form.

Again, I'll be running two different tests: one running on ASGI and then the next running on WSGI. I'll be doing it matched-pairs style in which I will first run the ASGI test then the WSGI and then vice versa the next day.

That makes a total of 4 views. Lastly, I'll be implementing a personal favorite view of mine: cached responses.

It's nice to have a database and all, but once a website starts rolling, caching functionality is key to keeping the server alive and making sure requests don't time out or is blocked due to natural Denial of Service due to server runtime. I'll be using aioredis, asgiref's sync_to_async, and naturally redis-py accordingly.

I've left out authentication in all these views and decided not to setup something like Traefik for HTTPS as to maintain as pure of a development server as possible.

In addition to all of this, I wanted to also try out psycopg3. Although it's currently in early development, it's a worthwhile task to see the efficiency boost, completely without asgiref doing the context switches.

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License

Licensed under the MIT License