Periodic tasks with Celery Beat in Django - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Celery Beat in Django?

Celery Beat is a scheduler that kicks off tasks at regular intervals, like a clock. It works with Celery to run periodic tasks automatically.

beginner

How do you define a periodic task using Celery Beat?

You define a periodic task by adding it to the Celery Beat schedule, specifying the task name and how often it should run (e.g., every 10 minutes).

intermediate

What is the role of the 'celery.py' file in setting up Celery Beat?

The 'celery.py' file configures Celery for your Django project, including setting up the broker and backend. The Beat scheduler is typically started as a separate process.

beginner

Why is it important to run both Celery worker and Celery Beat processes?

Celery worker runs the tasks, while Celery Beat schedules when tasks should run. Both are needed for periodic tasks to work properly.

advanced

How can you ensure your periodic tasks are reliable and do not overlap?

Use task locking or set task time limits to prevent overlap. Also, configure Celery Beat to use a persistent scheduler to keep track of tasks.

What does Celery Beat do in a Django project?

A Manages database migrations

B Processes tasks immediately

C Stores task results

D Schedules tasks to run periodically

Celery Beat schedules tasks to run at set intervals, like a timer.

Which command starts the Celery Beat scheduler?

A celery -A proj worker

B python manage.py runserver

C celery -A proj beat

D celery -A proj migrate

The 'celery -A proj beat' command starts the scheduler that triggers periodic tasks.

Where do you define the schedule for periodic tasks in Celery Beat?

A In the Celery app configuration

B In Django models.py

C In the database migrations

D In the Django settings.py only

Periodic task schedules are defined in the Celery app configuration, often in 'celery.py' or a dedicated schedule file.

What happens if you run only the Celery worker without Celery Beat for periodic tasks?

A Tasks will run twice

B Periodic tasks will not be scheduled

C The worker will crash

D Tasks will run automatically

Without Celery Beat, no periodic tasks are scheduled, so they won't run automatically.

How can you prevent a periodic task from running multiple times at once?

A Use task locking or time limits

B Run multiple Celery workers

C Restart Celery Beat frequently

D Use Django signals

Task locking or time limits help ensure a task does not overlap with itself.

Explain how Celery Beat works with Celery to run periodic tasks in Django.

Think about the roles of scheduler and worker.

Describe the steps to set up a periodic task using Celery Beat in a Django project.

Start from configuration to running processes.