I recently had to deploy a Flask web app for Hush Little Baby Early Childhood Music Classes (shameless plug) with uWSGI. (Sidenote: Flask + SQLAlchemy + WTForms = awesome.) I ran into an extremely exasperating issue which I thought I'd document here in case anyone else runs into it.

Despite the fact that uWSGI recommends that you run a separate instance for each app, I prefer the dynamic app approach. While i certainly understand why separate instances are recommended, I think per-app instances waste resources, especially when they have a lot of common dependencies, including Python itself. I also set uWSGI to use multiple threads. Unfortunately, with Flask, this is a recipe for disaster.