[R-SIG-Mac] OpenMP on CRAN (Simon Urbanek)

Fri May 1 07:51:31 CEST 2020

Thank you Simon for the official instruction and explanation about caveats!
I've tried to use libomp (9.0.1) you've provided and everything works
smoothly.
With new R4.0 toolchain and optional openmp support we got really good
tradeoff between simplicity for the majority of the users and feature-rich
set-up for more tech-savvy users.

On Fri, May 1, 2020 at 5:29 AM Simon Urbanek <simon.urbanek using r-project.org>
wrote:

> I have now created a page about this:
>
> http://mac.r-project.org/openmp
>
> which also provides libomp binaries for all recent versions of Xcode (and
> more).
>
> Important note: this is about Xcode - it is NOT about using Homebrew tools
> nor the custom compilers we used before R 4.0.0. Both of the latter are not
> suitable for use with R 4.0.0 binaries.
>
> Please give it a shot. Thanks for those participating in the discussion.
>
> Cheers,
> Simon
>
>
>
> > On 1/05/2020, at 2:23 AM, Wright, Erik Scott <ESWRIGHT using pitt.edu> wrote:
> >
> > Hi Kevin et al.,
> >
> > The setup you suggested did not work for me, but I was able to get
> OpenMP to work on Mac (10.13) with R v4.0 packages.  Here's what I did:
> >
> > (1) After installing Homebrew, ran
> > brew install libomp
> > # Note it is also possible to install from OpenMP Source code:
> https://releases.llvm.org/download.html#10.0.0
> > (2) Determined the install path with
> > brew --prefix libomp
> > # In my case /usr/local/opt/libomp
> > (3) Added lines to ~/.R/Makevars
> > CC=/usr/local/clang4/bin/clang -fopenmp -I/usr/local/opt/libomp/include
> > LDFLAGS=-L/usr/local/opt/libomp/lib
> >
> > I imagine the process is similar for C++ code by setting CXX.  Now
> parallelization for C code with OpenMP is working again on Mac.
> >
> > As always, I am thankful to the R community for helping problem solve.
> >
> > I wish more direction along these lines could be added to
> mac.r-project.org
> >
> > Erik
> >
> >
> >> On Apr 29, 2020, at 1:51 AM, Dmitriy Selivanov <
> selivanov.dmitriy using gmail.com> wrote:
> >>
> >> Thanks, Kevin, I can confirm suggested setup works fine so far. Thank
> you!
> >>
> >> I understand it, is that there's
> >> no guarantee that this will work properly (or continue to work
> >> properly) as the Apple toolchain continues to be updated -- e.g. a new
> >> version of macOS / Xcode could install a version of Apple Clang that
> >> is then incompatible with the version of libomp currently in use. In
> >> such a case, I suspect one would need to find and reinstall libomp.
> >>
> >> Thats understandable.
> >>
> >> On Sat, Apr 25, 2020 at 8:09 PM Kevin Ushey <kevinushey using gmail.com>
> wrote:
> >> The following works for me on macOS 10.15.4 using Apple Clang + libomp
> >> from LLVM 10 (via Homebrew).
> >>
> >> Install libomp from Homebrew with:
> >>
> >>     brew install libomp
> >>
> >> Then, put the following in ~/.R/Makevars
> >>
> >>     CPPFLAGS += -I/usr/local/opt/libomp/include -Xclang -fopenmp
> >>     LDFLAGS += -L/usr/local/opt/libomp/lib -lomp
> >>
> >> Then R will automatically enable + use OpenMP as appropriate when
> >> installing packages from sources.
> >>
> >> The main danger of this approach, as I understand it, is that there's
> >> no guarantee that this will work properly (or continue to work
> >> properly) as the Apple toolchain continues to be updated -- e.g. a new
> >> version of macOS / Xcode could install a version of Apple Clang that
> >> is then incompatible with the version of libomp currently in use. In
> >> such a case, I suspect one would need to find and reinstall libomp.
> >>
> >> In theory, this could be alleviated by ensuring all users download and
> >> use the same version of Xcode as is being used by the macOS build
> >> machine (Xcode 10.1), but in practice users will likely just be using
> >> the "default" set of command line tools that comes with their version
> >> of macOS.
> >>
> >> Cunningham's law will hopefully ensure someone else will chime in if
> >> I've got something wrong :-)
> >>
> >> Best,
> >> Kevin
> >>
> >> On Sat, Apr 25, 2020 at 8:29 AM Wright, Erik Scott <ESWRIGHT using pitt.edu>
> wrote:
> >> >
> >> > I second this request.  Dropping OpenMP support in R v4.0 on Mac is
> unfortunate.  My R package is highly parallelized via OpenMP, and many of
> my end-users take advantage of the excellent speedups.  It would be much
> appreciated if user-level instructions could be provided for how to enable
> OpenMP support on the Mac.
> >> >
> >> > Thanks,
> >> > Erik
> >> >
> >> >
> >> > > On Apr 23, 2020, at 7:08 AM, Dmitriy Selivanov <
> selivanov.dmitriy using gmail.com> wrote:
> >> > >
> >> > > Hi Simon,
> >> > >
> >> > > Just wanted follow up on this topic.
> >> > >
> >> > > It would be very helpful if you can provide some guide on
> >> > >
> https://nam05.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmac.r-project.org%2F&data=02%7C01%7Ceswright%40pitt.edu%7C65097590dea4453ab8cf08d7e776b868%7C9ef9f489e0a04eeb87cc3a526112fd0d%7C1%7C0%7C637232369415901734&sdata=qlhXuEubgD6PNmkbD%2BWQy5OI9X%2BGjxSYHMNjA%2BQHZzI%3D&reserved=0
> <
> https://nam05.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmac.r-project.org%2F&data=02%7C01%7Ceswright%40pitt.edu%7C65097590dea4453ab8cf08d7e776b868%7C9ef9f489e0a04eeb87cc3a526112fd0d%7C1%7C0%7C637232369415911728&sdata=5XR5LJuAKu4%2B3%2FUHsWVPMlyXTLY87P6OF%2FP%2FTZt1W8Y%3D&reserved=0>
> for those users
> >> > > (advanced?) and developers who wants to be able to use OpenMP on
> mac. From
> >> > > what I've understood from this mail thread the easiest way is to
> install R
> >> > > from homebrew as it is built with non-standard Apple toolchain.
> >> > > Apart from that you've mentioned you may consider to bundle binary
> iomp
> >> > > with R installation, but "it would be on the package author to make
> sure
> >> > > that the way the package operates is compatible with that binary".
> Could
> >> > > you please elaborate on that?
> >> > >
> >> > > I believe I'm not alone who would like to be able to use OpenMP on
> mac and
> >> > > "official" guidance would be very helpful.
> >> > >
> >> > > --
> >> > > Regards
> >> > > Dmitriy Selivanov
> >> > >
> >> > >       [[alternative HTML version deleted]]
> >> > >
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> >>
> >>
> >> --
> >> Regards
> >> Dmitriy Selivanov
> >
>
>

-- 
Regards
Dmitriy Selivanov

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