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On Mon, Jul 07, 2014 at 09:28:16AM +0200, Sylvain Bauza wrote:
> Le 04/07/2014 10:41, Daniel P. Berrange a écrit :
> > On Thu, Jul 03, 2014 at 03:30:06PM -0400, Russell Bryant wrote:
> >> On 07/03/2014 01:53 PM, Sylvain Bauza wrote:
> >>> That doesn't mean Gantt will move forward and leave all missing features
> >>> out of it, we will be dedicated to feature-parity as top priority but
> >>> that implies that the first releases of Gantt will be experimental and
> >>> considered for testing purposes only.
> >> I don't think this sounds like the best approach.  It sounds like effort
> >> will go into maintaining two schedulers instead of continuing to focus
> >> effort on the refactoring necessary to decouple the scheduler from Nova.
> >>  It's heading straight for a "nova-network and Neutron" scenario, where
> >> we're maintaining both for much longer than we want to.
> > Yeah, that's my immediate reaction too. I know it sounds like the Gantt
> > team are aiming todo the right thing by saying "feature-parity as the
> > top priority" but I'm concerned that this won't work out that way in
> > practice.
> >
> >> I strongly prefer not starting a split until it's clear that the switch
> >> to the new scheduler can be done as quickly as possible.  That means
> >> that we should be able to start a deprecation and removal timer on
> >> nova-scheduler.  Proceeding with a split now will only make it take even
> >> longer to get there, IMO.
> >>
> >> This was the primary reason the last gantt split was scraped.  I don't
> >> understand why we'd go at it again without finishing the job first.
> > Since Gantt is there primarily to serve Nova's needs, I don't see why
> > we need to rush into a split that won't actually be capable of serving
> > Nova needs, rather than waiting until the prerequisite work is ready. 
> 
> Thanks Dan and Russell for the feedback. The main concern about the
> scheduler split is when
> it would be done, if Juno or later. The current changes I raised are
> waiting to be validated, and the main blueprint (isolate-scheduler-db)
> is not yet validated before July 10th (Spec Freeze) so there is risk
> that the efforts would be done on the K release (unless we get an
> exception here)

Where is the sense of urgency for spltting scheduler in Juno coming
from ? I worry that even if you get all the dependent bits done and
we manage to split Gantt out, it is going to end up being a rather
last minute split. It feels to me that any time we intend to split
code out into a separate project, it is the kind of surgery that
should be done right at the start of a dev cycle. ie before a first
milestone release. Any code split has the potential for disrupting
dev, build & test procedures, so not something appealing to do near
the end of a dev cycle when we're under alot of pressure to review &
merge stuff to get out the final stable release.

Regards,
Daniel
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