[R-package] Add an R GPU job in CI

[jameslamb]

Summary

CMake-based builds of the R package support building a GPU-accelerated version of LightGBM (https://github.com/microsoft/LightGBM/blob/master/R-package/README.md#installing-a-gpu-enabled-build).

This feature is not currently tested in a continuous integration (CI) job, but it should be.

Motivation

The lack of automated tests for the R GPU package means it can be broken by changes in this repo, and we might not find out until those become user-facing issues (like the one reported in #3765 ).

Description

To close this issue, add a job to https://github.com/microsoft/LightGBM/blob/706f2af7badc26f6ec68729469ec6ec79a66d802/.github/workflows/r_package.yml that installs with a command like Rscript build_r.R --use-gpu and then runs the R tests.

          - os: ubuntu-latest
            task: r-package-gpu
            compiler: gcc
            r_version: 4.0
            build_type: cmake

References

You might need to reuse of some of the GPU setup for the Python "gpu" tasks

• LightGBM/.ci/setup.sh

  Line 67 in 706f2af

  if [[ $TASK == "gpu" ]]; then

• LightGBM/.ci/test.sh

  Line 127 in 706f2af

  if [[ $TASK == "gpu" ]]; then

[jameslamb]

Adding this to #2302 with other feature requests. Anyone is welcome to contribute this! Leave a comment if you'd like to contribute this and the issue can be re-opened.

[jaredlander]

While I can't contribute, I'd like to encourage further development (I know, I know, asking but not helping, but I think cheerleading is a form of helping, right?). While I know getting the GPU version onto CRAN would be hard, if there are prebuilt binaries the way {catboost} installs using devtools::install_url() that would be a step in the right direction.

On the other hand, if you're making progress toward getting the GPU version on the CRAN that will be awesome.

And yes @jameslamb, I'm putting together a course (not just a slideshow) and want this for the "more speed" part of the course.

[jameslamb]

Thanks for stopping by @jaredlander !

Unless another maintainer here or an outside contributor comes to help us with this, this issue is not going to be picked up for at least a month. Personally, my focus right now is on the new Dask integration (#3872 (comment)).

You're welcome to build the GPU version of the R package yourself, following https://github.com/microsoft/LightGBM/blob/master/R-package/README.md#installing-a-gpu-enabled-build

[jaredlander]

Those build instructions don't seem to be too bad compared to what I've from other GPU packages. I'm certainly game for trying but I don't know if I could expect all of my attendees to do that.

I bet this could be added to GitHub Actions (or maybe this one) pretty easily. I would try but I'm just getting started with Actions and don't know enough about them. So I am hoping another maintainer could add it.

[jaredlander]

Oh, btw, maybe someone from the team should give a talk at the meetup about this package.

[jameslamb]

I bet this could be added to GitHub Actions (or maybe this one) pretty easily

I expect it will be harder than just running R CMD INSTALL --build, to generate binaries that we feel confident will work well on a wide range of GPUs. It took significant effort to do something similar in LightGBM's Python package (#3403, #3144), and even after that effort those wheels are only supported on Windows.

It's a valuable feature, but I just want to be sure we set good expectations about the amount of effort required to add it.

If I'm wrong and this is straightforward, we'd welcome a PR to add this support. So if you know some people who have experience with building R packages that take advantage of GPUs, we'd be grateful if you'd encourage them to come help out on this.

Oh, btw, maybe someone from the team should give a talk at the meetup about this package.

Thanks. I'd be happy to come speak if you'd like! You can email me at jaylamb20@gmail.com if you want to talk about possible topics and scheduling.

[jaredlander]

If I'm wrong and this is straightforward, we'd welcome a PR to add this support. So if you know some people who have experience with building R packages that take advantage of GPUs, we'd be grateful if you'd encourage them to come help out on this.

I'm hoping it's just a matter of adding Rscript build_r.R --use-gpu to the Actions yml, I very much do not know that.

Thanks. I'd be happy to come speak if you'd like! You can email me at jaylamb20@gmail.com if you want to talk about possible topics and scheduling.

Will do, but are you sure you want your email on here?

[jameslamb]

Yeah it's totally fine. It's already public on my profile. But thanks for looking out!