[openstack-dev] [all] Status of the OpenStack port to Python 3

Victor Stinner vstinner at redhat.com
Fri Jun 24 08:14:00 UTC 2016

Le 23/06/2016 à 23:04, Thomas Goirand a écrit :
> Just think about it for a while. If we get Nova to work with Py3, and
> everything else is working, including all functional tests in Tempest,

Hum, that's a long list of expectations :-)

> then after Otaca, we could even start to *REMOVE* Py2 support after
> Otaca+1. That would be really awesome to stop all the compat layer
> madness and use the new features available in Py3.

Even if everything works well, I disagree that we must drop immediately 
Python 2 support. We should give time to deployers to prepare their 
migration to Python 3. We need at least have one cycle *fully* 
compatible with Python 3 to be able to *prepare* dropping Python 2 support.

In practice, we already support Python 2 and Python 3 in the same code 
base. We already paid the price of supporting both major versions. Once 
all code is ported, it shouldn't be too expensive to maintain both versions.

One concrete issue is that running tests on Python 2 *and* Python 3 
multiply the risk of random failures by 2. It's just math... In my 
experience, fixing random failures is not the most favorite task of 

If you want to deprecate Python 2, the first question is *when* we can 
start to make Python 2 checks non-voting.

> However, for this, it'd be super helful to have as much visibility as
> possible. Are we setting a hard deadline for the Otaca release? Or is
> this just a goal we only "would like" to reach, but it's not really a
> big deal if we don't reach it?

In my experience, Python 3 work is seen as background refactoring work, 
and it is rarely seen as high-priority. You should be prepared to have 
to wait :-)


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