I'm definitely +1 on the KIP concept. As Joe mentioned, we are already doing this in one form or the other. However, IMO it is fairly ad hoc - i.e., a combination of DISCUSS threads, jira comments, RB and code comments, wikis and html documentation. In the past I have had to dig into a bunch of these to try and figure out why something was implemented a certain way. I think KIPs can help a lot here first by providing guidelines on what to think about (compatibility, new APIs, etc.) when working through a major feature; and second by becoming a crisp source of truth documentation for new releases. E.g., for feature X: see relevant KIPs: a, b, c, etc.
On Thu, Jan 15, 2015 at 08:11:20PM -0800, Jay Kreps wrote: > Hey Joe, > > Yeah I guess the question is what is the definition of major? I agree we > definitely don't want to generate a bunch of paperwork. We have enough > problems just getting all the contributions reviewed and checked in in a > timely fashion... > > So obviously bug fixes would not apply here. > > I think it is also pretty clear that big features should get reviewed and > discussed. To pick on myself, for example, the log compaction work was done > without enough public discussion about how it worked and why (imho). I > hope/claim that enough rigour in thinking about use-cases and operations > and so on was done that it turned out well, but the discussion was just > between a few people with no real public output. This kind of feature is > clearly a big change and something we should discuss. > > If we limit ourselves to just the public contracts the KIP introduces the > discussion would just be on the new configs and monitoring without really a > discussion of the design and how it works which is obviously closely > related. > > I don't think this should be more work because in practice we are making > wiki pages for any big thing anyway. So this would just be a consistent way > of numbering and structuring these pages. This would also give a clear call > to action: "hey kafka people, come read my wiki and think this through". > > I actually thinking the voting aspect is less important. I think it is > generally clear when there is agreement on something and not. So from my > point of view we could actually just eliminate that part if that is too > formal, it just seemed like a good way to formally adopt something. > > To address some of your comments from the wiki: > > 1. This doesn't inhibit someone coming along and putting up a patch. It is > just that when they do if it is a big thing introducing new functionality > we would ask for a little discussion on the basic feature/contracts prior > to code review. > > 2. We definitely definitely don't want people generating a lot of these > things every time they have an idea that they aren't going to implement. So > this is only applicable to things you absolutely will check in code for. We > also don't want to be making proposals before things are thought through, > which often requires writing the code. So I think the right time for a KIP > is when you are far enough along that you know the issues and tradeoffs but > not so far along that you are going to be totally opposed to any change. > Sometimes that is prior to writing any code and sometimes not until you are > practically done. > > The key problem I see this fixing is that there is enough new development > happening that it is pretty hard for everyone to review every line of every > iteration of every patch. But all of us should be fully aware of new > features, the ramifications, the new public interfaces, etc. If we aren't > aware of that we can't really build a holistic system that is beautiful and > consistent across. So the idea is that if you fully review the KIPs you can > be sure that even if you don't know every new line of code, you know the > major changes coming in. > > -Jay > > > > On Thu, Jan 15, 2015 at 12:18 PM, Joe Stein <joe.st...@stealth.ly> wrote: > > > Thanks Jay for kicking this off! I think the confluence page you wrote up > > is a great start. > > > > > > The KIP makes sense to me (at a minimum) if there is going to be any > > "breaking change". This way Kafka can continue to grow and blossom and we > > have a process in place if we are going to release a thorn ... and when we > > do it is *CLEAR* about what and why that is. We can easily document which > > KIPs where involved with this release (which I think should get committed > > afterwards somewhere so no chance of edit after release). This approach I > > had been thinking about also allows changes to occur as they do now as long > > as they are backwards compatible. Hopefully we never need a KIP but when > > we do the PMC can vote on it and folks can read the release notes with > > *CLEAR* understanding what is going to break their existing setup... at > > least that is how I have been thinking about it. > > > > > > Let me know what you think about this base minimum approach... I hadn't > > really thought of the KIP for *ANY* "major change" and I have to think more > > about that. I have some other comments for minor items in the confluence > > page I will make once I think more about how I feel having a KIP for more > > than what I was thinking about already. > > > > > > I do think we should have "major changes" go through confluence, mailing > > list discuss and JIRA but kind of feel we have been doing that already ... > > if there are cases where that isn't the case we should highlight and learn > > from them and formalize that more if need be. > > > > > > /******************************************* > > Joe Stein > > Founder, Principal Consultant > > Big Data Open Source Security LLC > > http://www.stealth.ly > > Twitter: @allthingshadoop <http://www.twitter.com/allthingshadoop> > > ********************************************/ > > > > On Thu, Jan 15, 2015 at 1:42 PM, Jay Kreps <jay.kr...@gmail.com> wrote: > > > > > The idea of KIPs came up in a previous discussion but there was no real > > > crisp definition of what they were. Here is an attempt at defining a > > > process: > > > > > > > > https://cwiki.apache.org/confluence/display/KAFKA/Kafka+Improvement+Proposals > > > > > > The trick here is to have something light-weight enough that it isn't a > > > hassle for small changes, but enough so that changes get the eyeballs of > > > the committers and heavy users. > > > > > > Thoughts? > > > > > > -Jay > > > > >
