[openstack-dev] [nova] Port Nova to Python 3

Clint Byrum clint at fewbar.com
Fri Apr 24 23:20:00 UTC 2015

Excerpts from Sean Toner's message of 2015-04-24 05:38:42 -0700:
> If written to use python 3, I hope it will use all the new features of 
> python 3.4 moving forward.
> For example, argument annotations, coroutines, asyncio, etc.  At my last
> workplace, we tried to make our project python2 and 3 compatible (ie, 
> you could run it under 2.7 or 3.3+) but this was the worst of all 
> worlds.

Sean, this is a very developer-centric way of thinking.

Our operators will likely roll out python3 interpreters at a different
cadence than they roll out releases of OpenStack.

The best of both worlds is working perfectly fine on python 2.7 and
3.4+ until 2.7 is eradicated entirely, so that our operators can manage
change effectively.

The reason for this port is as much because 2.7 has an EOL that is
approximately 5 years away as anything else. If we are not on top of
this, OpenStack will be dependent on dead software rapidly. It has taken
2+ years to get this far with effort happening on the edges. I suspect it
will take another cycle before we start turning on gates, and then another
2 cycles before we're comfortable telling people to run OpenStack on 3.x.

So, we have to be patient with the new shiny, but we have to be very
_impatient_ with broken things.

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