Require libgomp on Linux

[jakirkham]

Looks like OpenMP is used for the builds on macOS, but the dependency is not included on Linux. This adds libgomp on Linux to provide OpenMP support on that platform.

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Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[conda-forge-webservices]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[jjerphan]

Hi @jakirkham, thank you for contributing.

Have you observed any problems at runtime with the current build (e.g. no thread parallelism?).

[jakirkham]

Thanks Julien! 🙏

A colleague was seeing a rather strange error message in relation to scinkit-learn usage ( dask-contrib/dask-sql#1144 (comment) ), which when digging more deeply can be caused by GNU OpenMP either being missing or not found correctly ( for example: opencv/opencv#14884 (comment) )

As LLVM OpenMP is included here for macOS and the usual recommendation suggests requiring GNU OpenMP on Linux too, thought we could give this change a try

It's possible the issue encountered has other causes, but this would at least rule out one (while improving the package here as well)

Would be curious to hear your thoughts on all of this? 🙂

[jjerphan]

Thank you for providing context.

scikit-learn's builds for Linux distributed on conda-forge has been depending on libgomp implicitly since the support of OpenMP but I think that it is appropriate specifying it explicitly for portability (since it allows switching to llvm-openmp if needed).

I am waiting for another maintainer's approval before merging.

[thomasjpfan]

This change makes sense to me. LGTM!

[jakirkham]

Thanks Julien & Thomas! 🙏

[jjerphan]

Thank you for resolving problems across packages in the ecosystem, John.

I hope to see you at the Scientific Python Developer Summit. 🌳

[jakirkham]

Ofc!

Hoping to come over there today 😄