Gunicorn vs Waitress: What are the differences?

Gunicorn and Waitress are both Python web servers used for deploying web applications. Here are the key differences between the two.

1. Concurrency Model: Gunicorn follows a pre-fork worker model, where a master process forks multiple worker processes to handle incoming requests. This approach allows for efficient utilization of resources by utilizing multiple CPU cores effectively. On the other hand, Waitress employs a multi-threaded architecture, using threads to handle concurrent requests. This model is typically suited for I/O-bound applications.

2. Scalability: Gunicorn offers better scalability compared to Waitress, especially for CPU-bound applications. By utilizing multiple worker processes, Gunicorn can handle a higher number of requests concurrently and distribute the load across multiple cores. Waitress, on the other hand, is more suitable for scenarios where the number of concurrent clients is relatively lower.

3. Configuration Options: Gunicorn provides a wide range of configuration options, allowing finer control over various server parameters. These options include the number of worker processes, worker class, timeout settings, and more. Waitress, on the other hand, offers a simpler configuration setup with fewer customizable parameters.

4. Ease of Use: Waitress is designed to be lightweight and easy to use. Its simplicity makes it a good choice for small to medium-sized applications with straightforward deployment requirements. Gunicorn, on the other hand, may require more effort in configuration and setup, but it also offers more flexibility and advanced features.

5. Supported WSGI Standards: Gunicorn supports both the WSGI (Web Server Gateway Interface) and ASGI (Asynchronous Server Gateway Interface) standards, providing compatibility with a wide range of Python web frameworks. Waitress, on the other hand, primarily focuses on supporting the WSGI standard and may not be suitable for applications that rely on the ASGI protocol.

6. Performance: In terms of performance, Gunicorn is often considered faster and more efficient compared to Waitress. The pre-fork worker model used by Gunicorn allows it to handle a higher number of concurrent requests efficiently, especially for CPU-bound workloads. However, Waitress can still provide good performance for I/O-bound applications.

In summary, Gunicorn is a pre-fork server known for its ability to handle concurrent requests efficiently, often used with various web frameworks, while Waitress is a simpler, production-ready server focusing on simplicity and ease of use, suitable for smaller applications and scenarios where lightweight performance is a priority.