Decide if partitioning all meshes in a multigrid mesh file

[ukmo-juan-castillo]

PR Summary

Sci/Tech Reviewer:
Code Reviewer:

Partitioning all meshes in the multigrid mesh file imposes a series of conditions regarding the number of CPUs that can be used in a job. For flexibility, it would be desirable to give the option of partitioning all multigrid meshes or not. This functionality is already present in lfric_core via the any_maps parameter of the get_partition subroutine of the panel_decomposition_type object. On the other hand, this object subroutine is not called directly in most applications, so this functionality should be made more accessible.

The solution proposed here is the creation of a logical variable in the global_mesh object, with set/get subroutines, indicating if the multiple meshes have to be partitioned. This is similar to what is presently done, where the global_mesh variable ntarget_meshes is used to find if there are multiple meshes.

Other solutions have been considered, for example:
. Extracting the any_maps parameter of the subroutine get_partition contained in the object panel_decomposition_type in successive subroutine calls until it can be used in the calling subroutine create_local_mesh. This would imply large changes in both lfric_core and lfric_apps
. Doing the same as before, but using optional subroutine parameters. Although this would minimise the number of changes in lfric_core and lfric_apps, the addition of new optional subroutine parameters is discouraged.
. Make changes in lfric applications to use the existing any_maps parameter of the subroutine get_partition. Lfric_core would not change, but this would imply duplicating large pieces of lfric_core code in the lfric_app applications that would make use of this functionality.
. Removing the checks altogether. This probably has implications in code robustness and cause runtime issues.

Any other suggestion by the reviewer would be considered and tested if necessary.

• linked Lfric2lfric no multi partition lfric_apps#291

• closes Select partitioning of multigrid meshes #288

• fixes Select partitioning of multigrid meshes #288

Code Quality Checklist

• I have performed a self-review of my own code
• My code follows the project's style guidelines
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Testing

• I have tested this change locally, using the LFRic Core rose-stem suite
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trac.log

Test Suite Results - lfric_core - lfric2lfric_no_multi_partition_core/run1

Suite Information

Item	Value
Suite Name	lfric2lfric_no_multi_partition_core/run1
Suite User	juan.m.castillo
Workflow Start	2026-02-25T15:47:23
Groups Run	all

Dependency	Reference	Main Like
lfric_core	ukmo-juan-castillo/lfric_core@lfric2lfric_no_multi_partition	False
SimSys_Scripts	MetOffice/SimSys_Scripts@2025.12.1	True

Task Information

✅ succeeded tasks - 384

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