Hi Peff, On Thu, 7 Feb 2019, Jeff King wrote: > On Thu, Feb 07, 2019 at 04:41:57PM +0100, Johannes Schindelin wrote: > > > > I think this can be limited to the tests that failed, which makes things > > > much faster. I.e., we run the tests at the tip of topic X and see that > > > t1234 fails. We then go back to the fork point and we just need to run > > > t1234 again. If it succeeds, then we blame X for the failure. If it > > > fails, then we consider it a false positive. > > > > If you mean merge bases by fork points, I wrote an Azure Pipeline to do > > that (so that I could use the cloud as kind of a fast computer), but that > > was still too slow. > > > > Even when there are even only as much as 12 merge bases to test (which is > > the current number of merge bases between `next` and `pu`), a build takes > > roughly 6 minutes on Windows, and many tests take 1 minute or more to run > > (offenders like t7003 and t7610 take over 400 seconds, i.e. roughly 6 > > minutes), we are talking about roughly 1.5h *just* to test the merge > > bases. > > I was assuming you're testing individual topics from gitster/git here > (which admittedly is more CPU in total than just the integration > branches, but it at least parallelizes well). Indeed. And there, I can usually figure out really quickly myself (but manually) what is going wrong. Hopefully we have Azure Pipelines enabled on https://github.com/git/git soon, with PR builds that include Windows (unlike our current Travis builds), so that contributors have an easier time to test their code in an automated fashion. I also have on my backlog a task to include `sparse` in the Azure Pipelines jobs. That should take care of even more things in a purely automated fashion, as long as the contributors look at those builds. > So with that assumption, I was thinking that you'd just look for the > merge-base of HEAD and master, which should give you a single point for > most topics. For inter-twined topics there may be more merge bases, but > I actually think for our purposes here, just testing the most recent one > is probably OK. I.e., we're just trying to have a vague sense of whether > the test failure is due to new commits or old. Oh, I am typically looking only at the latest commits up until I hit a merge commit. Usually that already tells me enough, and if not, a bisect is really quick on a linear history. I guess my dumb branch^{/^Merge} to find the next merge commit works, but it is a bit unsatisfying that we do not have a more robust way to say "traverse the commit history until finding a merge commit, then use that". > I think Junio's suggestion to just pick some common release points would > work OK in practice, too. It's possible that some other topic made it to > master with a breakage, but in most cases, I think these sorts of > failures are often more coarsely-grained (especially if Junio pays > attention to the CI results before merging). If Junio wants to experiment with that, sure, I'm all for it. Ciao, Dscho
