How many concurrent requests can flask handle?

Understanding the capacity of a Flask application to handle concurrent requests is crucial for web developers.

Default Flask Server and Concurrent Requests

By default, Flask uses Werkzeug’s development server. This server is single-threaded, which means it can handle only one request at a time. When a request is being processed, other requests have to wait in a queue until the server is free to handle them.

This kind of setup is not suitable for the production environment where multiple users might be accessing the application simultaneously.

How to handle more requests in Flask using Gunicorn

To handle the number of concurrent requests using a Flask application, we can use production-ready WSGI servers like Gunicorn or uWSGI. Using these servers, we can run multiple instances of the Flask application, either as separate processes or threads, which handle multiple requests at the same time.

For example, Gunicorn can be used to deploy the Flask application with multiple worker processes:

gunicorn -w 4 myapp:app

In the above example, -w 4 means Gunicorn will start 4 worker processes. Each process can handle one request at a time, so this setup can handle 4 concurrent requests.