eventlet gevent

https://blog.gevent.org/2010/02/27/why-gevent/
https://zhuanlan.zhihu.com/p/420890013

About the --app argument

The --app argument specifies the Celery app instance to use, in the form of module.path:attribute

But it also supports a shortcut form. If only a package name is specified, it’ll try to search for the app instance, in the following order:

With --app=proj:

1. an attribute named proj.app, or

2. an attribute named proj.celery, or

3. any attribute in the module proj where the value is a Celery application, or

If none of these are found it’ll try a submodule named proj.celery:

4. an attribute named proj.celery.app, or

5. an attribute named proj.celery.celery, or

6. Any attribute in the module proj.celery where the value is a Celery application.

This scheme mimics the practices used in the documentation – that is, proj:app for a single contained module, and proj.celery:app for larger projects.