Flask vs Gunicorn: What are the differences?

Flask vs Gunicorn

Flask and Gunicorn are both popular frameworks used in web development, but they have key differences in terms of their functionality and performance.

1. Deployment Approach: Flask is a micro web framework that is often used as a development server, suitable for small applications or prototypes. On the other hand, Gunicorn is a production-ready WSGI server that is designed to handle heavy traffic and high loads, making it better suited for large-scale applications.

2. Concurrency Model: Flask runs in a single process, which means it can only handle one request at a time. Gunicorn, on the other hand, uses a pre-fork worker model, allowing it to handle multiple requests concurrently. This makes Gunicorn more efficient in handling simultaneous requests and improves the overall performance of the application.

3. Scalability: Due to its single process nature, Flask may struggle to handle a high volume of concurrent requests, leading to potential bottlenecks and slower response times. Gunicorn, with its ability to handle multiple requests concurrently, is better equipped to handle scalability and can scale horizontally by adding more worker processes when needed.

4. Load-balancing: While Flask does not provide built-in load-balancing capabilities, Gunicorn can be easily configured to work with a load balancer like Nginx. This allows requests to be distributed across multiple instances of Gunicorn running on different servers, ensuring better distribution of load and improved performance.

5. HTTP Server Features: Flask does not include built-in support for handling HTTP server features like HTTP/2, keep-alive connections, and websocket support. In contrast, Gunicorn provides these features out of the box, making it a more suitable choice for applications that require advanced HTTP functionality.

6. Memory Usage: Flask consumes less memory compared to Gunicorn due to its lightweight design and minimalistic feature set. Gunicorn, being a more robust server, requires more memory to handle its multiple worker processes and additional features.

In summary, Flask is a lightweight micro web framework suitable for small-scale applications, while Gunicorn is a production-ready server that offers better scalability, load-balancing capabilities, and advanced HTTP server features for large-scale applications.