Frequently Asked Questions (FAQ)

FAQ

Can I use Faust with Django/Flask/etc.?

Yes! Use gevent or eventlet as a bridge to integrate with asyncio.

Using gevent

This approach works with any blocking Python library that can work with gevent.

Using gevent requires you to install the aiogevent module, and you can install this as a bundle with Faust:

$ pip install -U faust[gevent]

Then to actually use gevent as the event loop you have to either use the -L option to the faust program:

$ faust -L gevent -A myproj worker -l info

or add import mode.loop.gevent at the top of your entry point script:

#!/usr/bin/env python3
import mode.loop.gevent

REMEMBER: It’s very important that this is at the very top of the module, and that it executes before you import libraries.

Using eventlet

This approach works with any blocking Python library that can work with eventlet.

Using eventlet requires you to install the aioeventlet module, and you can install this as a bundle along with Faust:

$ pip install -U faust[eventlet]

Then to actually use eventlet as the event loop you have to either use the -L argument to the faust program:

$ faust -L eventlet -A myproj worker -l info

or add import mode.loop.eventlet at the top of your entry point script:

#!/usr/bin/env python3
import mode.loop.eventlet  # noqa

Warning

It’s very important this is at the very top of the module, and that it executes before you import libraries.

Can I use Faust with Tornado?

Yes! Use the tornado.platform.asyncio bridge: http://www.tornadoweb.org/en/stable/asyncio.html

Can I use Faust with Twisted?

Yes! Use the asyncio reactor implementation: https://twistedmatrix.com/documents/17.1.0/api/twisted.internet.asyncioreactor.html

Will you support Python 3.5 or earlier?

There are no immediate plans to support Python 3.5, but you are welcome to contribute to the project.

Here are some of the steps required to accomplish this:

  • Source code transformation to rewrite variable annotations to comments

    for example, the code:

         class Point:
             x: int = 0
             y: int = 0
    
    must be rewritten into::
    
         class Point:
             x = 0  # type: int
             y = 0  # type: int
    
  • Source code transformation to rewrite async functions

    for example, the code:

    async def foo():
        await asyncio.sleep(1.0)
    

    must be rewritten into:

    @coroutine
    def foo():
        yield from asyncio.sleep(1.0)
    

Will you support Python 2?

There are no plans to support Python 2, but you are welcome to contribute to the project (details in the question above is relevant also for Python 2).

I get a maximum number of open files exceeded error by RocksDB when running a Faust app locally. How can I fix this?

You may need to increase the limit for the maximum number of open files. The following post explains how to do so on OS X: https://blog.dekstroza.io/ulimit-shenanigans-on-osx-el-capitan/