On Thu, Aug 7, 2014 at 10:05 AM, Stefano Maffulli <stef...@openstack.org> wrote: > On Wed 06 Aug 2014 02:10:23 PM PDT, Michael Still wrote: >> - we rate limit the total number of blueprints under code review at >> any one time to a fixed number of "slots". I secretly prefer the term >> "runway", so I am going to use that for the rest of this email. A >> suggested initial number of runways was proposed at ten. > > oooooh, I like the 'slots/runaway model'. Sounds to me like kan ban (in > the Toyota sense not the hipster developer sense). > > A light in my head just went on. > > Let me translate what you're thinking about in other terms: the > slot/runaway model would switch what is now a push model into a "pull" > model. Currently we have patches coming in, pushed up for review. We > have then on gerrit reviewers and core reviewers shuffling through > these changesets, doing work and approve/comment. The reviewers have > little to no way to notice when they're overloaded and managers have no > way either. There is no way to identify when the process is suffering, > slowing down or not satisfying demand, if not when the backlog blows > up. As recent discussions demonstrate, this model is failing under our > growth.
I agree, although I hadn't thought of the length of the backlog as something that we could use to report on our overload until you mentioned it. I think there is a risk here, because it would be naive to assume that the solution to a long review backlog would be to add more core reviewers -- we need to be careful about quality as well as quantity. > By switching to a model where we have a set of slots/runaway (buckets, > in Toyota's terminology) reviewers would have a clear way to *pull* new > reviews into their workstations to be processed. It's as simple as a > supermaket aisle: when there is no more pasta on the shelf, a clerk > goes in the backend and gets more pasta to refurbish the shelf. There > is no sophisticated algorithm to predict demand: it's the demand of > pasta that drives new pull requests (of pasta or changes to review). > > This pull mechanism would help make it very visible where the > bottlenecks are. At Toyota, for example, the amount of kanbans is the > visible way to understand the capacity of the plant. The amount of > slots/runaways would probably give us similar overview of the capacity > of each project and give us tools to solve bottlenecks before they > become emergencies. > > I think you guys are on to something, I'd be very happy to formalize a > proposal. Who should I talk to? You should ping John Garbutt and Dan Smith, as they're the ones I recall tricking. Michael -- Rackspace Australia _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
