Thanks for the notes Andrew, Junping, Karthik. Here are some of my understandings:
- Trunk is the "latest and greatest" of Hadoop. If a user starts using Hadoop today, without legacy workloads, trunk is what he/she should use. - Therefore, each commit to trunk should be transactional -- atomic, consistent, isolated (from other uncommitted patches); I'm not so sure about durability, Hadoop might be gone in 50 years :). As a committer, I should be able to look at a patch and determine whether it's a self-contained improvement of trunk, without looking at other uncommitted patches. - Some comments inline: On Fri, Jun 10, 2016 at 6:56 AM Junping Du <j...@hortonworks.com> wrote: > Comparing with advantages, I believe the disadvantages of shipping any > releases directly from trunk are more obvious and significant: > - A lot of commits (incompatible, risky, uncompleted feature, etc.) have > to wait to commit to trunk or put into a separated branch that could delay > feature development progress as additional vote process get involved even > the feature is simple and harmless. > Thanks Junping, those are valid concerns. I think we should clearly separate incompatible with uncompleted / half-done work in this discussion. Whether people should commit incompatible changes to trunk is a much more tricky question (related to trunk-incompat etc.). But per my comment above, IMHO, *not committing uncompleted work to trunk* should be a much easier principle to agree upon. > - For small feature with only 1 or 2 commits, that need three +1 from PMCs > will increase the bar largely for contributors who just start to contribute > on Hadoop features but no such sufficient support. > Development overhead is another valid concern. I think our rule-of-thumb should be that, small-medium new features should be proposed as a single JIRA/patch (as we recently did for HADOOP-12666). If the complexity goes beyond a single JIRA/patch, use a feature branch. > > Given these concerns, I am open to other options, like: proposed by Vinod > or Chris, but rather than to release anything directly from trunk. > > - This point doesn't necessarily need to be resolved now though, since > again we're still doing alphas. > No. I think we have to settle down this first. Without a common agreed and > transparent release process and branches in community, any release (alpha, > beta) bits is only called a private release but not a official apache > hadoop release (even alpha). > > > Thanks, > > Junping > ________________________________________ > From: Karthik Kambatla <ka...@cloudera.com> > Sent: Friday, June 10, 2016 7:49 AM > To: Andrew Wang > Cc: common-...@hadoop.apache.org; hdfs-dev@hadoop.apache.org; > mapreduce-...@hadoop.apache.org; yarn-...@hadoop.apache.org > Subject: Re: [DISCUSS] Increased use of feature branches > > Thanks for restarting this thread Andrew. I really hope we can get this > across to a VOTE so it is clear. > > I see a few advantages shipping from trunk: > > - The lack of need for one additional backport each time. > - Feature rot in trunk > > Instead of creating branch-3, I recommend creating branch-3.x so we can > continue doing 3.x releases off branch-3 even after we move trunk to 4.x (I > said it :)) > > On Thu, Jun 9, 2016 at 11:12 PM, Andrew Wang <andrew.w...@cloudera.com> > wrote: > > > Hi all, > > > > On a separate thread, a question was raised about 3.x branching and use > of > > feature branches going forward. > > > > We discussed this previously on the "Looking to a Hadoop 3 release" > thread > > that has spanned the years, with Vinod making this proposal (building on > > ideas from others who also commented in the email thread): > > > > > > > http://mail-archives.apache.org/mod_mbox/hadoop-common-dev/201604.mbox/browser > > > > Pasting here for ease: > > > > On an unrelated note, offline I was pitching to a bunch of > > contributors another idea to deal > > with rotting trunk post 3.x: *Make 3.x releases off of trunk directly*. > > > > What this gains us is that > > - Trunk is always nearly stable or nearly ready for releases > > - We no longer have some code lying around in some branch (today’s > > trunk) that is not releasable > > because it gets mixed with other undesirable and incompatible changes. > > - This needs to be coupled with more discipline on individual > > features - medium to to large > > features are always worked upon in branches and get merged into trunk > > (and a nearing release!) > > when they are ready > > - All incompatible changes go into some sort of a trunk-incompat > > branch and stay there till > > we accumulate enough of those to warrant another major release. > > > > Regarding "trunk-incompat", since we're still in the alpha stage for > 3.0.0, > > there's no need for this branch yet. This aspect of Vinod's proposal was > > still under a bit of discussion; Chris Douglas though we should cut a > > branch-3 for the first 3.0.0 beta, which aligns with my original > thinking. > > This point doesn't necessarily need to be resolved now though, since > again > > we're still doing alphas. > > > > What we should get consensus on is the goal of keeping trunk stable, and > > achieving that by doing more development on feature branches and being > > judicious about merges. My sense from the Hadoop 3 email thread (and the > > more recent one on the async API) is that people are generally in favor > of > > this. > > > > We're just about ready to do the first 3.0.0 alpha, so would greatly > > appreciate everyone's timely response in this matter. > > > > Thanks, > > Andrew > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: common-dev-unsubscr...@hadoop.apache.org > For additional commands, e-mail: common-dev-h...@hadoop.apache.org > >
