feat: refactor partitioners by bd713 · Pull Request #3847 · GEOS-DEV/GEOS

bd713 · 2025-10-05T00:32:15Z

Description

This PR introduces a complete refactoring of GEOS's mesh partitioning system with a new architecture that separates partitioning algorithms (engines) from domain decomposition strategies (partitioners).

In practice, a new DomainPartitioner abstract base class is introduced with two main specialized branches:

DomainPartitioner (Abstract Base)
├── GeometricPartitioner (Abstract)
│   ├── CartesianPartitioner (Concrete)
│   └── ParticleCartesianPartitioner (Concrete)
└── MeshPartitioner (Abstract)
    ├── CellGraphPartitioner (Concrete)
    └── LayeredMeshPartitioner (Concrete)

The mesh partitioners leverage low-level graph partitioner engines that are independent from MPI communication:

GraphPartitionEngine (Abstract Engine Interface)
├── ParMetisEngine (Concrete)
├── PTScotchEngine (Concrete)
└── NoOpEngine (Concrete)

A PartitionerManager is introduced for creating and managing partitioner instances.

XML Changes

Partitioning configuration moved from mesh-embedded to dedicated <Partitioner> section.

Before:

<Mesh>
   <VTKMesh
       file="mesh.vtu"
       partitionMethod="parmetis"
       partitionRefinement="2"  />
</Mesh>

After:

<Partitioner>
  <CellGraphPartitioner engine="parmetis" numRefinements="1"/>
</Partitioner>
<Mesh>
  <VTKMesh file="mesh.vtu"/>
</Mesh>

Default behavior
If no partitioner is prescribed, an appropriate default is selected based on mesh type:

Internal meshes: CartesianPartitioner
External meshes: CellGraphPartitioner with ParMetis

To skip graph partition optimization, explicitly use engine="noop".

Testing & Rebaseline

Due to XML schema changes a rebaseline is required.
However no numerical impact is expected.

INFO: Total number of log files processed: 1047

INFO: No unfiltered differences were found.

All currently failing integrated tests are due to structural changes such as:

********************************************************************************
Error: /Problem
	Group has a child 'Partitioner' in the file to compare but not the baseline file.
********************************************************************************
********************************************************************************
Error: /Problem/domain
	Group has a child 'partitionManager' in the baseline file but not the file to compare.
********************************************************************************

…ncePartitioner

paveltomin · 2025-11-03T19:38:51Z

@bd713 why did you change some tests inputs? defaults should be fine, no?

bd713 · 2025-11-04T18:08:15Z

@bd713 why did you change some tests inputs? defaults should be fine, no?

For external meshes, the default remains unchanged: ParMetis is run once with no additional refinement iteration.
Hence, only tests that relied on a non-default partitionRefinement must be updated.

Matrix conversion:
partitionRefinement=0 => Explicitly use NoOp engine
partitionRefinement=1 (default) => No changes needed, the new default numRefinements=0 will be used, following Metis convention
partitionRefinement=3 (i.e. run ParMetis + 2 extra refinements) => Explicitly set numRefinements=2

We also have 1 test using ptscotch that needs to be edited as well.

MelReyCG

The PR looks good to me, but I do not have knowledge in partitioners, I left some remarks:

Should the package name be something like partitioner rather than mpiCommunications (or could it be splitted?)

MelReyCG · 2025-11-19T14:41:28Z

 using namespace dataRepository;

-class SpatialPartition;
+//class SpatialPartition;


MelReyCG · 2025-11-19T17:03:39Z

+   * @brief Get partition counts in all directions
+   * @return Array of partition counts {nx, ny, nz}
+   */
+  array1d< int > const & getPartitionCounts() const { return m_partitionCounts; }


Why this array size is not fixed?

Suggested change

array1d< int > const & getPartitionCounts() const { return m_partitionCounts; }

R1Tensor const & getPartitionCounts() const { return m_partitionCounts; }

or

Suggested change

array1d< int > const & getPartitionCounts() const { return m_partitionCounts; }

stackArray1D< int, 3 > const & getPartitionCounts() const { return m_partitionCounts; }

MelReyCG · 2025-12-15T14:31:16Z

+// Modulo
+// returns a positive value regardless of the sign of numerator
+real64 Mod( real64 const num, real64 const denom )


Doxygen format?

(here and below)

MelReyCG · 2025-12-15T14:59:44Z

+   */
+  unsigned int getZPartitions() const { return m_partitionCounts[2]; }
+
+  real64 const * getLocalMin() const { return m_localMin;}


Feels unsafe to return an unsized array through a pointer.

MelReyCG · 2025-12-15T15:08:19Z

+  array1d< int > m_partitionCounts;
+
+  /// Local subdomain minimum (x, y, z)
+  real64 m_localMin[3];


stackArray1D< int, 3 > ?

MelReyCG · 2025-12-15T15:34:37Z

+/**
+ * @class GraphPartitionEngine
+ * @brief Abstract interface for low-level graph partitioning algorithms
+ *
+ * This is a LOW-LEVEL engine for pure algorithms: graph -> partition IDs
+ */
+class GraphPartitionEngine : public dataRepository::Group
+{


Does it really have to be a Group, or should it be an interface (abstract pure class / templated variant)?

MelReyCG · 2025-12-15T15:48:28Z

 {

-class SpatialPartition;
+//class SpatialPartition;


MelReyCG · 2025-12-15T15:51:53Z

+    ArrayOfArraysView< pmet_idx_t const, pmet_idx_t > const & graph,
+    arrayView1d< pmet_idx_t const > const & vertDist,


There is a lot of const-cast. Should we remove those const qualifier?

DENEL Bertrand added 14 commits October 1, 2025 23:13

PartitionerManager

1ba2ed5

removed unused PartitionDescriptor

40d4683

Updated SurfaceGenerator

89cdc70

EmbeddedSurfaceGenerator

e0488a3

MeshGeneratorBase

2841595

InternalMeshGenerator

60682c6

InternalMeshGenerator

156597b

InternalWellboreGenerator

cd9691b

ProblemManager

2b25b46

ProblemManager

fa077a2

More

07a8eac

renamed original to keep track of history

16405ff

added refactored versions

32d7ffb

Working version but Still with debug prints

4c2a873

bd713 self-assigned this Oct 5, 2025

bd713 added the type: cleanup / refactor Non-functional change (NFC) label Oct 5, 2025

bd713 requested a review from rrsettgast as a code owner October 5, 2025 00:32

bd713 added the changes XML input label Oct 5, 2025

bd713 requested review from CusiniM, corbett5 and paveltomin as code owners October 5, 2025 00:32

bd713 added the DO NOT MERGE ! label Oct 5, 2025

bd713 requested review from Guotong-Ren, MelReyCG, OmarDuran, castelletto1, dkachuma, jhuang2601, matteofrigo5 and wrtobin as code owners October 5, 2025 00:32

DENEL Bertrand added 3 commits October 10, 2025 14:05

Merge remote-tracking branch 'origin/develop' into feature/bd713/enha…

6db5f21

…ncePartitioner

virtual color

10c9cf9

duplicate cart

bd11cf3

bd713 removed the flag: requires rebaseline Requires rebaseline branch in integratedTests label Oct 12, 2025

DENEL Bertrand added 5 commits October 12, 2025 16:24

periodic

eab11c2

periodic

faf7785

partitionRefinement

8d9cafc

Merge remote-tracking branch 'origin/develop' into feature/bd713/enha…

5d36530

…ncePartitioner

temp partitioner

3487249

bd713 added the ci: run CUDA builds label Oct 13, 2025

DENEL Bertrand added 2 commits October 13, 2025 23:45

clean

1199477

catalog

5ce56de

bd713 removed the ci: run CUDA builds label Oct 15, 2025

bd713 force-pushed the feature/bd713/enhancePartitioner branch from 45ad26f to 5ce56de Compare October 22, 2025 17:54

DENEL Bertrand added 8 commits October 22, 2025 13:43

RestartFlags

d3369fe

Merge remote-tracking branch 'origin/develop' into feature/bd713/enha…

0601dd3

…ncePartitioner

stdMap

bfec144

Merge remote-tracking branch 'origin/develop' into feature/bd713/enha…

b105e2b

…ncePartitioner

numRefinements

eb325e2

Merge remote-tracking branch 'origin/develop' into feature/bd713/enha…

a9214c6

…ncePartitioner

ptscotch

e628619

m_engine

6561381

bd713 added flag: ready for review flag: requires rebaseline Requires rebaseline branch in integratedTests and removed DO NOT MERGE ! labels Oct 25, 2025

paveltomin approved these changes Nov 4, 2025

View reviewed changes

MelReyCG reviewed Dec 15, 2025

View reviewed changes

bd713 closed this May 8, 2026

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feat: refactor partitioners - #3847

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	array1d< int > const & getPartitionCounts() const { return m_partitionCounts; }
	R1Tensor const & getPartitionCounts() const { return m_partitionCounts; }

	array1d< int > const & getPartitionCounts() const { return m_partitionCounts; }
	stackArray1D< int, 3 > const & getPartitionCounts() const { return m_partitionCounts; }

		ArrayOfArraysView< pmet_idx_t const, pmet_idx_t > const & graph,
		arrayView1d< pmet_idx_t const > const & vertDist,

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Description

XML Changes

Testing & Rebaseline

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bd713 commented Oct 5, 2025 •

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