Main merge release/25.12 3

[rgsl888prabhu]

For #693

Summary by CodeRabbit

• Bug Fixes

  • Improved thread-safety for concurrent termination handling across solver components.
  • Enhanced logger configuration reuse to prevent unnecessary reinitialization.

• Performance

  • Added node exploration limits per diving subtree to improve solver efficiency.

• Chores

  • Updated dependency specifications to use stable release versions.
  • Added pre-commit validation hook for release verification.

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Review failed

The pull request is closed.

📝 Walkthrough

Walkthrough

This pull request introduces concurrency semantics improvements by replacing volatile keywords with atomic types across multiple components, implements a guard-based logger configuration system to preserve state across instances, adds diving exploration limits in dual simplex, and simplifies rapids-logger dependency specifications while resolving a merge conflict in conda environment configuration.

Changes

Cohort / File(s)	Summary
Concurrency Semantics Refactor (volatile → atomic) cpp/include/cuopt/linear_programming/pdlp/solver_settings.hpp, cpp/src/dual_simplex/branch_and_bound.hpp, cpp/src/dual_simplex/simplex_solver_settings.hpp, cpp/src/linear_programming/solve.cu, cpp/src/mip/diversity/diversity_manager.cuh, cpp/src/mip/relaxed_lp/relaxed_lp.cuh	Systematically replaces volatile int* with std::atomic<int>* for concurrent halt flags across solver components, improving thread-safety guarantees and atomic operation semantics.
Dual Simplex Diving Exploration Control cpp/src/dual_simplex/branch_and_bound.cpp	Introduces per-subtree diving node exploration counter with a hard cap of 1000 nodes, tracking exploration effort and enabling early exit from diving loops.
Logger Configuration Guard System cpp/src/utilities/logger.cpp, cpp/src/utilities/logger.hpp	Implements reference-counted guard mechanism to preserve and reuse logger configuration across multiple init\_logger\_t instances using weak/strong references and mutex-protected state management.
Dependency Specification Simplifications dependencies.yaml, python/cuopt/cuopt/linear_programming/pyproject.toml, python/cuopt/pyproject.toml, python/libcuopt/pyproject.toml	Simplifies rapids-logger constraints from rapids-logger==0.2.*,>=0.0.0a0 to rapids-logger==0.2.*, removing pre-release lower bounds.
Build Configuration .pre-commit-config.yaml	Adds verify-alpha-spec hook from rapidsai/pre-commit-hooks with --fix and --mode release arguments; adjusts indentation of default\_language\_version mapping.
Unresolved Merge Conflict conda/environments/all_cuda-129_arch-x86_64.yaml	Contains unresolved merge conflict markers in cudf dependency specification (HEAD: 26.2.*,>=0.0.0a0 vs. release/25.12: 25.12.*).

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~50 minutes

• Logger architectural refactor (cpp/src/utilities/logger.cpp): Complex state management involving weak/strong reference counting, mutex synchronization, and behavioral shifts from explicit destructor cleanup to guard lifetime semantics. Requires careful verification of initialization/reuse logic and guard lifecycle.
• Atomic refactor verification (6 files): Systematic volatile-to-atomic conversion across concurrency-critical paths. Each file requires independent verification that atomic semantics preserve intended behavior and that pointer/value access patterns are correctly updated.
• Merge conflict resolution (conda/environments/all_cuda-129_arch-x86_64.yaml): Blocker requiring determination of intended cudf version before PR can proceed.
• Diving exploration algorithm (cpp/src/dual_simplex/branch_and_bound.cpp): Logic changes introducing counters and control flow branches need verification against algorithm correctness.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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📜 Recent review details

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 89ebcbb and d54e18e.

📒 Files selected for processing (15)

• .pre-commit-config.yaml (2 hunks)
• conda/environments/all_cuda-129_arch-x86_64.yaml (1 hunks)
• cpp/include/cuopt/linear_programming/pdlp/solver_settings.hpp (1 hunks)
• cpp/src/dual_simplex/branch_and_bound.cpp (3 hunks)
• cpp/src/dual_simplex/branch_and_bound.hpp (2 hunks)
• cpp/src/dual_simplex/simplex_solver_settings.hpp (1 hunks)
• cpp/src/linear_programming/solve.cu (1 hunks)
• cpp/src/mip/diversity/diversity_manager.cuh (1 hunks)
• cpp/src/mip/relaxed_lp/relaxed_lp.cuh (1 hunks)
• cpp/src/utilities/logger.cpp (2 hunks)
• cpp/src/utilities/logger.hpp (1 hunks)
• dependencies.yaml (1 hunks)
• python/cuopt/cuopt/linear_programming/pyproject.toml (3 hunks)
• python/cuopt/pyproject.toml (1 hunks)
• python/libcuopt/pyproject.toml (2 hunks)

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