Celery Interview Questions for Freshers & Experienced
1. What is Celery?
Celery Message-oriented asynchronous task queue/job queue implementation for Python web applications that are based on distributed message passing approach1. It is released under a BSD License and used by internet giants like Instagram, AdrolL, Mozilla Addons and many more.
2. List some features of Celery?
Major features of Celery framework are
- Job Scheduling
- Job Monitoring
- Managing Workflows
- Time & Rate Limiting
- Autoloading and Resource Leak Protection.
3. What is a Broker?
In Celery broker is a mediator between clients and workers. The main task of the broker is to deliver the client messages to a worker.
4. What is the alternative to Celery Python?
Dramatic is one of the most popular alternatives to Celery Python. It supports Redis and RabbitMQ message brokers.
5. How install Celery via pip?
To install Celery via pip run below commnad
pip install -U Celery
6. In which language Celery is written?
Celery is written in Python programming language.
7. What is Celery worker?
Celery worker is a supervisor process that does not process any tasks itself rather than that Celery spawns child processes (or threads) and deals with all the book keeping stuff.
8. What is Celery backend?
Celery backend is a storage place that is used for storing the task results.Currently Celery supports only AMQP, database, cache, Couchbase, and Redis backends.
9. What is Celerybeat?
Celerybeat is a task scheduler that sends predefined tasks to a celery worker at a given time.
10. What is Pub-Sub in Celery?
Pub-Sub expended as publish-subscribe or producer-consumer is a distributed messaging pattern where publishers broadcast messages over a message broker, and subscribers listen for the messages.
11. What is the alternative to Celery Python?
Dramatiq is a fast and reliable alternative to Celery. It supports RabbitMQ and Redis as message brokers.
12. How do I stop celery task?
You should use result.revoke:
>>> result = add.apply_async(args=[2, 2], countdown=180)
>>> result.revoke()
13.In which language Celery is written?
It is written in Python Language.
14. How to check task status in Celery?
In order for Celery to record that a task is running, you must use:
example_task.status() == RUNNING
15. What’s the difference between Celeryd and Celerybeat?
Celery executes tasks and Celerybeat schedules tasks.
Celery on a regular schedule helps to run batch jobs in the background while Celerybeat on the other hand is instructed on how to run all the tasks on a specific date or time.
16. Can we replace Celerybeat with Chronos?
Sure, we can replace celerybeat with chronos.Chronos supports RESTful submission of events with ISO8601 format and is useful for management as it can mitigate the necessity to use schedule tasks.