Support Python 3.7 and build wheels.

[robertnishihara]

This also involves

• Extending https://github.com/ray-project/ray/blob/master/python/build-wheel-macos.sh to build wheels for Python 3.7 (note that this will cause our MAC_WHEELS Travis build to definitely time out, so we need to figure out what to do about that (see Speed up Mac OS Travis builds. #1110).

[danielsuo]

While splitting out MacOS wheels, I thought I'd give 3.7 a try (why not, I was feeling alive). The plumbing in #1205 works, but the 3.7 build fails:

• Cython claims their latest release will build on CPython master, but I get fails for both Travis and locally using CPython 3.7a2
• The manylinux docker we're using doesn't have cp37-cp37m yet, which makes sense, though we probably want to work with the Arrow folks to put a beta / rc 3.7 into their image over the next few months

FYI: final release is 2018-06-15

[robertnishihara]

Related to apache/arrow#1125

[xhochy]

@danielsuo @robertnishihara if we can get a docker container of any linux distro that has a built version of Python 3.7, we should be able to set up a pipeline to build Arrow & Ray. apache/arrow#1125 is probably more related to some weird in the system setup than Python 3.7 itself, sadly I cannot reproduce it with Python 3.6 on ArchLinux so I'm struggling to narrow down the problem.

[danielsuo]

Would these work?

[xhochy]

@danielsuo they look like a good option.

[danielsuo]

Another option: fork the manylinux image, add 3.7, and make a failed build for 3.7 not fatal.

That said, it may be cleaner to have a separate workflow for 3.7 that we simply remove / replace with updated a manylinux image when the time comes. Is that what you had in mind?

[austinnichols101]

Bump. Python 3.7 is out (27-Jun).

[rubik]

Is there any new release planned now that Python 3.7 is in use in many linux distributions?

[robertnishihara]

Yeah, we should do this for the next release (0.6).

[timonbimon]

do you already have a rough idea when 0.6 will be released? :)

[robertnishihara]

@timonbimon our more aggressive timeline is roughly 1 month.

[timonbimon]

awesome, thanks for the amazing work :)

[sadatnfs]

Looks like Miniconda's latest (default) version download 3.7 now. I feel a lot of installs breaking :(

[pcmoritz]

Good point, thanks for bringing that up. It's in the works here: #2546, we can prioritize merging it soon.

[robertnishihara]

Fixed by #2546.

[robertnishihara]

The wheels still haven't been uploaded to PyPI, but you can get them by following the instructions at https://ray.readthedocs.io/en/latest/installation.html#trying-the-latest-version-of-ray and modifying the URL to use 3.7.

[manugarri]

any updates on this? Would like to be able to use ray on a windows machine. Maybe there is a conda binary available?

[robertnishihara]

@manugarri for Windows, the relevant issue is #631. We're working on it, but it isn't ready yet.

[manugarri]

got it, thanks!