This document describes an older version of Celery (2.2). For the latest stable version please go here.


Community Code of Conduct

The goal is to maintain a diverse community that is pleasant for everyone. That is why we would greatly appreciate it if everyone contributing to and interacting with the community also followed this Code of Conduct.

The Code of Conduct covers our behavior as members of the community, in any forum, mailing list, wiki, website, Internet relay chat (IRC), public meeting or private correspondence.

The Code of Conduct is heavily based on the Ubuntu Code of Conduct, and the Pylons Code of Conduct.

Be considerate.

Your work will be used by other people, and you in turn will depend on the work of others. Any decision you take will affect users and colleagues, and we expect you to take those consequences into account when making decisions. Even if it’s not obvious at the time, our contributions to Ubuntu will impact the work of others. For example, changes to code, infrastructure, policy, documentation and translations during a release may negatively impact others work.

Be respectful.

The Celery community and its members treat one another with respect. Everyone can make a valuable contribution to Celery. We may not always agree, but disagreement is no excuse for poor behavior and poor manners. We might all experience some frustration now and then, but we cannot allow that frustration to turn into a personal attack. It’s important to remember that a community where people feel uncomfortable or threatened is not a productive one. We expect members of the Celery community to be respectful when dealing with other contributors as well as with people outside the Celery project and with users of Celery.

Be collaborative.

Collaboration is central to Celery and to the larger free software community. We should always be open to collaboration. Your work should be done transparently and patches from Celery should be given back to the community when they are made, not just when the distribution releases. If you wish to work on new code for existing upstream projects, at least keep those projects informed of your ideas and progress. It many not be possible to get consensus from upstream, or even from your colleagues about the correct implementation for an idea, so don’t feel obliged to have that agreement before you begin, but at least keep the outside world informed of your work, and publish your work in a way that allows outsiders to test, discuss and contribute to your efforts.

When you disagree, consult others.

Disagreements, both political and technical, happen all the time and the Celery community is no exception. It is important that we resolve disagreements and differing views constructively and with the help of the community and community process. If you really want to go a different way, then we encourage you to make a derivative distribution or alternate set of packages that still build on the work we’ve done to utilize as common of a core as possible.

When you are unsure, ask for help.

Nobody knows everything, and nobody is expected to be perfect. Asking questions avoids many problems down the road, and so questions are encouraged. Those who are asked questions should be responsive and helpful. However, when asking a question, care must be taken to do so in an appropriate forum.

Step down considerately.

Developers on every project come and go and Celery is no different. When you leave or disengage from the project, in whole or in part, we ask that you do so in a way that minimizes disruption to the project. This means you should tell people you are leaving and take the proper steps to ensure that others can pick up where you leave off.

Reporting a Bug

Bugs can always be described to the Mailing list, but the best way to report an issue and to ensure a timely response is to use the issue tracker.

  1. Create a GitHub account.

You need to create a GitHub account to be able to create new issues and participate in the discussion.

  1. Determine if your bug is really a bug.

You should not file a bug if you are requesting support. For that you can use the Mailing list, or IRC.

  1. Make sure your bug hasn’t already been reported.

Search through the appropriate Issue tracker. If a bug like yours was found, check if you have new information that could be reported to help the developers fix the bug.

  1. Collect information about the bug.

To have the best chance of having a bug fixed, we need to be able to easily reproduce the conditions that caused it. Most of the time this information will be from a Python traceback message, though some bugs might be in design, spelling or other errors on the website/docs/code.

If the error is from a Python traceback, include it in the bug report.

We also need to know what platform you’re running (Windows, OSX, Linux, etc), the version of your Python interpreter, and the version of Celery, and related packages that you were running when the bug occurred.

  1. Submit the bug.

By default GitHub will email you to let you know when new comments have been made on your bug. In the event you’ve turned this feature off, you should check back on occasion to ensure you don’t miss any questions a developer trying to fix the bug might ask.

Issue Trackers

Bugs for a package in the Celery ecosystem should be reported to the relevant issue tracker.

If you are unsure of the origin of the bug you can ask the Mailing list, or just use the Celery issue tracker.

Coding Style

You should probably be able to pick up the coding style from surrounding code, but it is a good idea to be aware of the following conventions.

  • All Python code must follow the PEP-8 guidelines. is an utility you can use to verify that your code is following the conventions.

  • Docstrings must follow the PEP-257 conventions, and use the following style.

    Do this:

    def method(self, arg):
        """Short description.
        More details.


    def method(self, arg):
        """Short description."""

    but not this:

    def method(self, arg):
        Short description.
  • Lines should not exceed 78 columns.

  • Import order

    • Python standard library (import xxx)
    • Python standard library (‘from xxx import`)
    • Third party packages.
    • Other modules from the current package.

    or in case of code using Django:

    • Python standard library (import xxx)
    • Python standard library (‘from xxx import`)
    • Third party packages.
    • Django packages.
    • Other modules from the current package.

    Within these sections imports should be sorted by name.


    import threading
    import time
    from collections import deque
    from Queue import Queue, Empty
    from celery.datastructures import TokenBucket
    from celery.utils import timeutils
    from celery.utils.compat import all, izip_longest, chain_from_iterable
  • Wildcard imports must not be used (from xxx import *).

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