Hello, the protected master branch has successfully been switched to PR-merge https://issues.apache.org/jira/browse/INFRA-15833. In the next step, I'd like to remove PR-head from our CI. This means that in future only PR-merge will be executed.
Does anybody object? -Marco On Wed, Jan 10, 2018 at 9:40 PM, Marco de Abreu < [email protected]> wrote: > Thanks for your opinions. Could a committer please contact a mentor in > order to create an Apache Infra ticket to change the protected master > branch from PR-head to PR-merge? > > -Marco > > On Wed, Jan 10, 2018 at 9:26 PM, kellen sunderland < > [email protected]> wrote: > >> +1 >> >> On Wed, Jan 10, 2018 at 6:51 PM, Gautam <[email protected]> wrote: >> >> > +1 >> > >> > On Jan 10, 2018 1:25 AM, "Marco de Abreu" <[email protected] >> > >> > wrote: >> > >> > > Hello, >> > > >> > > TLDR: We wish to change how PRs are validated, turning off PR-head >> which >> > > tests PRs in their current branch, and turning on PR-merge, which >> tests >> > PRs >> > > rebased on the current master branch. We believe this will catch more >> > > potential errors that would otherwise get merged into master, and it >> > should >> > > not cause any extra work for commiters or reviewers. >> > > >> > > as announced in >> > > https://lists.apache.org/thread.html/92ca1942d67a87ee6a2b4d448c621e >> > > 433f2f8aca81e4d913d8b2537e@%3Cdev.mxnet.apache.org%3E >> > > and as probably most have noticed, we have been running an experiment >> > with >> > > the PR-validation-jobs. During the past month, every PR was checked by >> > the >> > > jobs called PR-head and PR-merge. In the past, only PR-head has been >> > > executed and was the required job to pass in order to merge a PR into >> the >> > > protected master branch. Before I continue any further, I’d like to >> > explain >> > > the detailed meaning of both jobs: >> > > >> > > PR-head: The PR and its commit history is taken as-is and tested in >> > exactly >> > > the same state as in your local fork. >> > > >> > > PR-merge: The PR and its commit history are rebased on top of latest >> > master >> > > commit and thus tested as if the PR would be merged at this point in >> > time. >> > > >> > > I have noticed that many PRs are rarely rebased before a merge. >> > Considering >> > > the fast development of MXNet, this could cause serious issues: >> Imagine a >> > > PR is based on a 4 weeks old commit and accesses an API which has been >> > > modified in the meantime. PR-head would report this PR as ready to >> merge >> > as >> > > the changes, based on the 4 weeks old commit. But as soon as a >> committer >> > > merges this PR into the master branch, the master branch will suddenly >> > > report errors because this PR tries to access an API which does not >> exist >> > > anymore. >> > > >> > > Using PR-merge will reduce the chance of this happening as the PR is >> > always >> > > getting rebased on top of the master branch before it is getting >> > validated. >> > > But there is one pitfall: CI only runs if a new commit is getting >> pushed. >> > > If a PR stays untouched for a certain amount of time it still could be >> > > possible that it missed a breaking change due to the fact that CI >> hasn’t >> > > been triggered for a while, but this happens quite rarely. In order to >> > > solve this problem, we could think about introducing a job which >> > validates >> > > PRs that haven’t been run for a week, but that’s a different >> discussion. >> > > Also, if multiple PRs get merged at the same time, conflicting changes >> > (in >> > > terms of changes in one part which cause another part to fail) could >> be >> > > introduced – but the committers who merge the PRs usually notice two >> > > conflicting PRs. Additionally, merge conflicts in terms of changing >> the >> > > same lines of code on the other hand will fail fast and tell the >> > > contributor in the GitHub-webinterface that they will have to resolve >> the >> > > merge-conflicts before the PR can be validated – it couldn’t be merged >> > with >> > > merge-conflicts anyways. >> > > >> > > PR-merge is a safer choice in terms of health for the master-branch. >> > Thus, >> > > I’d like to put it up for discussion to turn off PR-head and switch >> the >> > > required check to PR-merge. >> > > >> > > Does anybody object? >> > > >> > > Best regards, >> > > Marco >> > > >> > >> > >
