DEV Community

Sazzad-Ur-Rahman
Sazzad-Ur-Rahman

Posted on

Understanding Gunicorn: A Web Server for Python Applications

If you’re deploying Python web applications, chances are you’ve come across Gunicorn. But what exactly is it, and how does it work? Let’s break it down.

What is Gunicorn?
Gunicorn is a powerful web server for Python that’s known for being simple yet highly effective. It’s based on a UNIX pre-fork model, which means it starts a master process that creates multiple worker processes. These workers handle incoming HTTP requests.

How It Works:

Master Process: The master process is like the conductor of an orchestra. It ensures that the right number of worker processes are running. If one worker dies, the master quickly starts a new one to keep things moving smoothly.

Worker Processes: These are the musicians in our orchestra. Each worker is responsible for handling the actual HTTP requests. By default, each worker is an independent UNIX process, meaning they don’t share memory, which helps in better handling of tasks.

Concurrency in Gunicorn:
Gunicorn offers three main ways to handle multiple tasks (concurrency):
1.Workers: Each worker is a separate process. The recommended number of workers is (2 * CPU) + 1. For example, on a dual-core machine, 5 workers are ideal.
2.Threads: You can add threads within each worker process. This allows each worker to handle multiple tasks simultaneously. For example, you could run 3 workers with 3 threads each to handle 9 concurrent requests.The maximum concurrent requests are (workers * threads).
3.Async Workers: For even more concurrency, you can use libraries like gevent(pseudo-threads means virtual thread)or Asyncio, which let each worker handle many connections (up to 1000!) without the overhead of traditional threads.

Which Setup is Best?
For most cases, sticking with the recommended (2 * CPU) + 1 workers will give you solid performance. But if your app has lots of I/O-bound tasks (like waiting for data from a database), adding threads or going async can help you get the most out of your server.

One of the most common things, but I always seem to forget it 😃
Concurrency vs. Parallelism
Concurrency: is when 2 or more tasks are being performed at the same time, which might mean that only 1 of them is being worked on while the other ones are paused.
Parallelism: is when 2 or more tasks are executing at the same time.
hashtag#python hashtag#development hashtag#gunicorn

Top comments (0)