Currently, Travis CI has a job running tests on macOS. Sadly, there is a bug on Travis: *sometimes*, the macOS job blocks a Pull Request to be merged even if macOS is marked as "Allowed Failure". If you cancel the job, it's even worse: Travis CI is marked a failed and the PR cannot be merged.

I tried to cancel the build and restart it, but 2 hours later, the macOS job was still queued and I was still unable to merge my PR.

We cannot work around the Travis CI issue. We are getting more and more pull requests, especially this week with the CPython sprint, so the macOS queue is getting even longer.

I discussed the issue with Zachary Ware and we agreed to "disable" ("remove" in practice) the macOS job for this week, and rely on the macOS buildbots instead.

We have 3 macOS buildbots (x86 Tiger 3.x, x86-64 El Capitan 3.x, x86-64 Sierra 3.x) and I worked hard last months to get buildbots green. So we should be quickly notified of failures. There is now the buildbot-status mailing list for this purpose!

https://mail.python.org/mm3/mailman3/lists/buildbot-status.python.org/

I already reported the issue twice on python-committers mailing list in June and September (this year):

* https://mail.python.org/pipermail/python-committers/2017-September/004824.html
* https://mail.python.org/pipermail/python-committers/2017-June/004661.html

Failures of the two Allowed Failure jobs, coverage and macOS, are not reported to GitHub PR. For example, the coverage job is failing on Python 3.6 since May 2016 at least, and nobody noticed.

I don't think that it's worth it to waste Travis CI resources if nobody notices failures.

See https://github.com/python/core-workflow/issues/101 for the discussion on Allowed Failures on Travis CI.

Since Travis CI time is a bottleneck for the ongoing sprint, I agree that it makes sense to disable the macOS build checks for now.  Longer term, it would be nice to resolve the problem but we certainly could rely on our own macOS buildbots; I'm not aware of many (any?) instances yet where the Travis macOS instance has caught a problem.  I think Brett should make the call on whether to permanently disable this after he gets back.

I will note that my on-going research on rewriting the buildbot config makes it look like we should be able to securely enable building PRs by checking for the 'awaiting merge' label.

New changeset 501b324d3a940d26e0021a38aae8d896a30fbcff by Victor Stinner in branch 'master':
bpo-31355: Travis CI: remove the macOS job (#3367)
https://github.com/python/cpython/commit/501b324d3a940d26e0021a38aae8d896a30fbcff

New changeset 11453524ed26ee449275c32bedfd86ef19dd91ee by Ned Deily (Victor Stinner) in branch '3.6':
bpo-31355: Travis CI: remove the macOS job (#3367)
https://github.com/python/cpython/commit/11453524ed26ee449275c32bedfd86ef19dd91ee

New changeset 2bc83afb30850f682487ffa560c9e3663788baaa by Ned Deily (Victor Stinner) in branch '2.7':
bpo-31355: Travis CI: remove the macOS job (#3367)
https://github.com/python/cpython/commit/2bc83afb30850f682487ffa560c9e3663788baaa

> I'm not aware of many (any?) instances yet where the Travis macOS instance has caught a problem.

It did help me on some delicate signals/threading issues.

Should this be closed?

Yeah, I consider that the issue can now be closed. If someone really wants runnings checks on macOS, we should wait until Travis CI solves their issues, or find a different CI provider.

https://blog.travis-ci.com/2017-09-22-macos-update

The situation with macOS builds on Travis-CI is now much better (no more long waiting queues) so we might revisit this decision.

I'm willing to give it another go. Do you want to open a PR to turn it back on and see how the timing looks, Antoine?

Last macOS job took 13 minutes and there was almost no wait.  That looks ok.  I'm not sure it's required to backport to 3.6 and 2.7 since those branches typically have less churn.

Awesome, thanks for taking the time to verify all of that! And I agree with your logic to not bother backporting.

New changeset d7687eb4b66c9f675b112eff1169326a1766c111 by Antoine Pitrou in branch 'master':
bpo-31355: Travis-CI: re-enable macOS job (#5858)
https://github.com/python/cpython/commit/d7687eb4b66c9f675b112eff1169326a1766c111