This document describes the current stable version of Celery (5.0). For development docs, go here.

What’s new in Celery 5.0 (singularity)

Author

Omer Katz (omer.drow at gmail.com)

Celery is a simple, flexible, and reliable distributed programming framework to process vast amounts of messages, while providing operations with the tools required to maintain a distributed system with python.

It’s a task queue with focus on real-time processing, while also supporting task scheduling.

Celery has a large and diverse community of users and contributors, you should come join us on IRC or our mailing-list.

To read more about Celery you should go read the introduction.

While this version is mostly backward compatible with previous versions it’s important that you read the following section as this release is a new major version.

This version is officially supported on CPython 3.6, 3.7 & 3.8 and is also supported on PyPy3.

Table of Contents

Make sure you read the important notes before upgrading to this version.

Preface

The 5.0.0 release is a new major release for Celery.

Starting from now users should expect more frequent releases of major versions as we move fast and break things to bring you even better experience.

Releases in the 5.x series are codenamed after songs of Jon Hopkins. This release has been codenamed Singularity.

This version drops support for Python 2.7.x which has reached EOL in January 1st, 2020. This allows us, the maintainers to focus on innovating without worrying for backwards compatibility.

From now on we only support Python 3.6 and above. We will maintain compatibility with Python 3.6 until it’s EOL in December, 2021. We may choose to extend our support if a PyPy version for 3.7 will not become available by then but we don’t guarantee we will.

— Omer Katz

Long Term Support Policy

As we’d like to provide some time for you to transition, we’re designating Celery 4.x an LTS release. Celery 4.x will be supported until the 1st of August, 2021.

We will accept and apply patches for bug fixes and security issues. However, no new features will be merged for that version.

Celery 5.x is not an LTS release. We will support it until the release of Celery 6.x.

We’re in the process of defining our Long Term Support policy. Watch the next “What’s New” document for updates.

Wall of Contributors

Note

This wall was automatically generated from git history, so sadly it doesn’t not include the people who help with more important things like answering mailing-list questions.

Upgrading from Celery 4.x

Please read the important notes below as there are several breaking changes.

Important Notes

Supported Python Versions

The supported Python Versions are:

  • CPython 3.6

  • CPython 3.7

  • CPython 3.8

  • PyPy3.6 7.2 (pypy3)

Dropped support for Python 2.7 & 3.5

Celery now requires Python 3.6 and above.

Python 2.7 has reached EOL in January 2020. In order to focus our efforts we have dropped support for Python 2.7 in this version.

In addition, Python 3.5 has reached EOL in September 2020. Therefore, we are also dropping support for Python 3.5.

If you still require to run Celery using Python 2.7 or Python 3.5 you can still use Celery 4.x. However we encourage you to upgrade to a supported Python version since no further security patches will be applied for Python 2.7 and as mentioned Python 3.5 is not supported for practical reasons.

Kombu

Starting from this release, the minimum required version is Kombu 5.0.0.

Billiard

Starting from this release, the minimum required version is Billiard 3.6.3.

Eventlet Workers Pool

Due to eventlet/eventlet#526 the minimum required version is eventlet 0.26.1.

Gevent Workers Pool

Starting from this release, the minimum required version is gevent 1.0.0.

Couchbase Result Backend

The Couchbase result backend now uses the V3 Couchbase SDK.

As a result, we no longer support Couchbase Server 5.x.

Also, starting from this release, the minimum required version for the database client is couchbase 3.0.0.

To verify that your Couchbase Server is compatible with the V3 SDK, please refer to their documentation.

Riak Result Backend

The Riak result backend has been removed as the database is no longer maintained.

The Python client only supports Python 3.6 and below which prevents us from supporting it and it is also unmaintained.

If you are still using Riak, refrain from upgrading to Celery 5.0 while you migrate your application to a different database.

We apologize for the lack of notice in advance but we feel that the chance you’ll be affected by this breaking change is minimal which is why we did it.