When your Python web app needs to send emails or process images, you cannot make users wait for it to finish. You need a background worker, which is a separate process that handles slow tasks outside the main web request.

  • The core differences between Celery and Django Q
  • How to write basic tasks in both systems
  • When to choose the built-in feel of Django Q
  • When to scale up with Celery
  • Common performance mistakes to avoid

What is Celery?

Celery is the industry standard for running background tasks in Python. It is powerful and handles massive scale, but it requires a separate message broker like Redis to pass messages between your app and your workers.

Here is how you define a simple task using Celery:

from celery import shared_task

@shared_task
def send_welcome_email(user_id):
    # Imagine sending an email here
    print(f"Sending email to user {user_id}")

The takeaway is that Celery uses decorators to turn ordinary Python functions into asynchronous background jobs.

What is Django Q?

Django Q is an alternative task runner built specifically for Django. A message broker is a piece of software that stores and routes messages between different services; Django Q uses your existing PostgreSQL database as that broker instead of needing Redis.

Here is how you define a task using Django Q:

def send_welcome_email(user_id):
    # Imagine sending an email here
    print(f"Sending email to user {user_id}")

# To call it in your code:
from django_q.tasks import async_task
async_task('myapp.tasks.send_welcome_email', user_id)

The takeaway is that Django Q lets you trigger tasks using string paths and stores everything right in your database.

Django development Photo by Faisal on Unsplash

Common mistakes

A common mistake with Django Q is overloading your PostgreSQL database with task queues, which slows down your main web traffic. If you have thousands of tasks running every minute, move to Celery with Redis so your database can focus on user data. Another trap is passing complex Django model instances into tasks instead of just passing primary key IDs.

Stop reading about task queues and open your terminal right now. Install Django Q into your current project if you want to avoid managing extra infrastructure today.