What is the best option for a (Python 3) task queue on Windows now that Celery 4 has dropped Windows support?

Question

We run a Flask site under IIS on Windows, and for out-of-process tasks we use Celery. Celery has given us some problems under Windows, but for now we are satisfied running version 3.1.12, using RabbitMQ/AMQP as a back-end, which works under Windows.

The new version of Celery (4) has dropped support for Windows, so I'm looking for a viable alternative.

RQ seems a very nice task queue, but it also does not support Windows (bottom of the page)

I have seen some more, seemingly less popular task queues like:

• kuyruk
• tasktiger
• huey

But it's unclear if these support Windows and Flask. I'm wondering if anyone has experience running a Python task queue under Windows which works. Maybe one of the ones I mentioned, or an alternative.

It's not an option for us to run a Linux machine, because we have no experience administering Linux, and we have a lot of legacy stuff running that requires Windows.

Answer 1

I run Flask with Huey on Windows without any issues, admittedly only for development and testing. For production I use Flask/Huey on Linux servers. Both with the Redis back-end, Flask 0.12 and Huey 1.2.0 .

I use the factory pattern to create a specialised "cut down" version of a Flask app for specific use by Huey tasks. This version doesn't load blueprints or configure Flask-Admin as these aren't required in the Huey tasks.

Example code of __init__.py in app folder. App is a class extending from Flask:

def create_app(settings_override=None):      app = App('app')      if settings_override:         app.config.from_object(settings_override)     else:         app.config.from_object(os.environ['APP_SETTINGS'])      from .ext import configure_extensions     configure_extensions(app, admin, load_modules=True)      # REST     import rest.api_v1     app.register_blueprint(api_v1_bp, url_prefix='/api/v1')      #  ... and more suff   def create_huey_app():     app = App('huey app')      app.config.from_object(os.environ['APP_SETTINGS'])      from .ext import configure_extensions     configure_extensions(app, admin=None, load_modules=False)      return app 

The idea of configure_extensions is taken from Quokka CMS. Examine its app __init__.py and its extensions module to see how this is implemented. Note also how this project too creates a specific app (create_celery_app) for use with the Celery task queue.

Example of tasks.py. Note the use of with app.app_context(): to create the Flask context. Now my functions have access to the extensions such as Flask-Mail, Flask-SqlAlchemy (db, models) etc.

@huey.task() def generate_transaction_documents_and_email(transaction_id):     app = create_huey_app()     with app.app_context():         reports.generate_transaction_documents_and_email(transaction_id)   @huey.task() def send_email(subject, recipients, text_body, html_body, attachments=[], cc=[]):     app = create_huey_app()     with app.app_context():         emails.send_email(subject, recipients, text_body, html_body, attachments, cc)   @huey.periodic_task(crontab(minute='30')) def synchronize_mailing_list():     app = create_huey_app()     if app.config['CREATESEND_SYNCHRONIZE']:         _list_name = app.config['CREATESEND_LIST']         with app.app_context():             sync_delete_ar_subscribers(_list_name)             sync_add_ar_subscribers(_list_name)