Benchmark grdsample, grdfilter and sph2grd with fixed cores

[weiji14]

Description of proposed changes

Benchmarking OpenMP multi-threaded algorithms with a fixed number of CPU cores, to ensure consistency of benchmarks.

Using a fixed core count of 2, which is the maximum number of CPU cores for GitHub Actions' Linux runners - https://docs.github.com/en/actions/using-github-hosted-runners/about-github-hosted-runners/about-github-hosted-runners#supported-runners-and-hardware-resources

TODO:

• test_grdsample_dataarray_out
• test_sph2grd_no_outgrid
• test_grdimage_grid_and_shading_with_xarray[png] (errors, see Benchmark grdsample, grdfilter and sph2grd with fixed cores #2945 (comment))
• test_grdfilter_dataarray_in_dataarray_out

Fixes #2942

Reminders

• Run make format and make check to make sure the code follows the style guide.
• Add tests for new features or tests that would have caught the bug that you're fixing.
• Add new public functions/methods/classes to doc/api/index.rst.
• Write detailed docstrings for all functions/methods.
• If wrapping a new module, open a 'Wrap new GMT module' issue and submit reasonably-sized PRs.
• If adding new functionality, add an example to docstrings or tutorials.
• Use underscores (not hyphens) in names of Python files and directories.

Slash Commands

You can write slash commands (/command) in the first line of a comment to perform
specific operations. Supported slash commands are:

• /format: automatically format and lint the code
• /test-gmt-dev: run full tests on the latest GMT development version

[codspeed-hq]

CodSpeed Performance Report

Merging #2945 will not alter performance

_{⚠️ No base runs were found}

_{Falling back to comparing benchmark-fixed-cores (08f36d2) with main (8be628e)}

Summary

✅ 64 untouched benchmarks

[weiji14]

This line is raising an error at https://github.com/GenericMappingTools/pygmt/actions/runs/7404780202/job/20146784435?pr=2945#step:8:778:

 E           pygmt.exceptions.GMTCLibError: Module 'grdimage' failed with status code 72:
Error:      grdimage [ERROR]: Option -x given more than once
Error:      grdimage [ERROR]: Option -x parsing failure. Correct syntax:
Error:      grdimage [ERROR]: Offending option -x2

Equivalent GMT CLI command also fails (both on GMT 6.4.0 and GMT 6.5.0.dev9+0776994):

gmt grdimage @earth_relief_01d_g -RGL -Cgeo -x2 -png map

grdimage [ERROR]: Option -x given more than once
grdimage [ERROR]: Option -x parsing failure. Correct syntax:

   [-x[[-]<n>]] .
     Limit the number of cores used in multi-threaded algorithms [Default uses all 16 cores]. If <n> is negative then we select (16 - <n>) cores (or at least 1).
grdimage [ERROR]: Offending option -x2

Might be an upstream GMT bug?

[seisman]

very likely

[weiji14]

Ok, reported upstream at GenericMappingTools/gmt#8256. I've reverted the grdimage commit at 08f36d2 for now.