diogobaeder/async-flask-demo

Just a demo to show how to make Flask work with evented I/O

async-flask-demo

Just a demo to show how to make Flask work with evented I/O, and compare it with the FastAPI+Uvicorn stack.

Preparing your environment

Make sure you have "just" installed (it's a better "make").

Also, make sure you have Poetry installed:

$ pip install poetry

Running

To run the FastAPI stack:

$ just run-asyncio

To run the Flask stack:

$ just run-flask

Async Flask? Really?

Check for yourself: run this command in two different terminals:

$ time curl http://localhost:8001/sleep/10.0

You'll see that it does take roughly 10 seconds for each response, but with a single process. (With uWSGI this can be increased to more worker processes if need be, although the gevent thread count is quite high already.)

Performance

If you're curious about how they compare to each other in a very simple scenario where they need to do some non-blocking work, you can test the /sleep/<some-float> endpoint with something like Apache Bench. For example:

$ ab -c 1000 -n 2000 http://localhost:8001/sleep/1.0