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Expose distributed (multi-GPU) PDLP settings in the Java API - #1961

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Exposes distributed (multi-GPU) PDLP settings on the Java side — a typed DistributedPdlpPartitioner enum and setNumGpus/setUseDistributedPdlp/setDistributedPdlpPartitioner convenience methods, mirroring setMethod/setPDLPSolverMode. The underlying C++ constants already flow through automatically via the generated CuOptConstants and the generic setSetting/getSetting passthrough.

Like #1957, actually distributing a solve depends on the C API dispatch fix in #1958.

Fixes #1931

🤖 Generated with Claude Code

The C++ constants (num_gpus, use_distributed_pdlp,
distributed_pdlp_partitioner) already flow through the generated
CuOptConstants and SolverSettings' generic setSetting/getSetting. This
adds a typed DistributedPdlpPartitioner enum and typed convenience
setters, mirroring setMethod/setPDLPSolverMode, plus docs and a test.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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📝 Walkthrough

Walkthrough

The Java API adds distributed PDLP configuration for GPU count, enablement, and partitioning. It adds the DistributedPdlpPartitioner enum, documents the new options, and tests typed setting retrieval.

Changes

Distributed PDLP Java API

Layer / File(s) Summary
API configuration
java/cuopt/src/main/java/com/nvidia/cuopt/mathematicaloptimization/DistributedPdlpPartitioner.java, java/cuopt/src/main/java/com/nvidia/cuopt/mathematicaloptimization/SolverSettings.java
Adds partitioner options and SolverSettings methods for GPU count, distributed PDLP, and partitioner selection.
Validation and documentation
java/cuopt/src/test/java/com/nvidia/cuopt/mathematicaloptimization/NativeIntegrationTest.java, docs/cuopt/source/cuopt-java/convex/convex-api.rst
Tests typed retrieval of the new settings and documents the configuration methods and partitioner options.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Feature

Suggested reviewers: afender

Merge Risk: 🔵 Low · up to 64fc5

The API works, but its documentation can mislead Java users configuring GPU counts or distributed PDLP. This is low risk and straightforward to correct.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name Status Explanation Resolution
Docstring Coverage ⚠️ Warning Docstring coverage is 42.86% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 7 functions across 3 files. (1 skipped: 1… Write docstrings for the functions missing them to satisfy the coverage threshold.
✅ Passed checks (4 passed)
Check name Status Explanation
Title check ✅ Passed The title clearly summarizes the main change: exposing distributed multi-GPU PDLP settings in the Java API.
Description check ✅ Passed The description accurately explains the new Java API enum, convenience methods, documentation, dependency on the C API fix, and linked issue.
Linked Issues check ✅ Passed The PR implements the Java API portion of [#1931]. It adds DistributedPdlpPartitioner with AUTO, KAMINPAR, and ROUND_ROBIN, adds SolverSettings.setNumGpus, setUseDistributedPdlp, and `setD…
Out of Scope Changes check ✅ Passed The changed files are limited to Java API implementation, its integration test, and Java API documentation. Each change supports the multi-GPU PDLP API objective in [#1931]. No unrelated product behav…
Full details: Docstring Coverage

Explanation

Docstring coverage is 42.86% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 7 functions across 3 files. (1 skipped: 1 unsupported.)

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Actionable comments posted: 1


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Inline comments:
In
`@java/cuopt/src/main/java/com/nvidia/cuopt/mathematicaloptimization/SolverSettings.java`:
- Line 72: Update SolverSettings documentation at
java/cuopt/src/main/java/com/nvidia/cuopt/mathematicaloptimization/SolverSettings.java:72
to state that positive values select an explicit GPU count, reserving the
greater-than-one requirement for distributed PDLP. Update
docs/cuopt/source/cuopt-java/convex/convex-api.rst:104-105 to specify that
distributed PDLP requires SolverMethod.PDLP and setNumGpus(-1) or a value
greater than 1, with -1 meaning all GPUs visible to the process.

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📒 Files selected for processing (4)
  • docs/cuopt/source/cuopt-java/convex/convex-api.rst
  • java/cuopt/src/main/java/com/nvidia/cuopt/mathematicaloptimization/DistributedPdlpPartitioner.java
  • java/cuopt/src/main/java/com/nvidia/cuopt/mathematicaloptimization/SolverSettings.java
  • java/cuopt/src/test/java/com/nvidia/cuopt/mathematicaloptimization/NativeIntegrationTest.java

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* Graph partitioning strategy used to split a problem across GPUs when distributed (multi-GPU)
* PDLP is used, backed by constants generated from the C++ public header.
*/
public enum DistributedPdlpPartitioner {

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Are you sure you want these to be an enum? The challenge with enums is that they require propagation throughout all the APIs. Whereas a regular integer setting should be automatically propagated through the API. What if we just made the partitioner setting an int?

…stributed PDLP

-1 resolves to all visible GPUs, which is only one GPU on a
single-GPU host; distributed sharding requires more than one GPU
actually selected.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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[FEA] Support mGPU PDLP in C/Python/Java API

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