Question

My Flask stops responding when uploading files or when collecting data from another server via GET. I assume, the problem is, that Flask is only running on one thread.

How can I change this, so multiple users can use the site?

Answer 1

Flask’s development webserver (invoked when you use app.run) is not a production web server.

Quoting the docs:

You can use the builtin server during development, but you should use a full deployment option for production applications. (Do not use the builtin development server in production.)

If you want to use Flask in a production environment take a look at the deployment options suggested by the documentation.

For testing purposes with small applications that are doing slightly complicated things I deploy the code I’m developing behind CherryPy using this snippet. (The only disadvantage of this pattern is you loose access to Werkzeug’s debugger.)