Performance improvements: reduce allocations in discretization hot paths #501
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Key optimizations: - Replace nested reduce(safe_vcat, ...) patterns with pre-allocated arrays and push!/append! - Use sizehint! to pre-allocate result arrays with estimated sizes - Add _append_vec! helper for efficient vector/matrix appending - Replace array comprehensions with tuples where stencil sizes are small/fixed - Use Sets instead of nested reduce for building unique collections - Direct returns instead of intermediate placeholder arrays These changes reduce allocation overhead in the core discretization pipeline, particularly in generate_cartesian_rules, generate_finite_difference_rules, and discretize_equation_at_point functions. Added allocation regression tests to prevent future regressions. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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Summary
This PR reduces memory allocations in the core discretization hot paths, improving performance by approximately 5-6% on typical 1D problems.
Key optimizations:
reduce(safe_vcat, ...)patterns with pre-allocated arrays andpush!/append!sizehint!to pre-allocate result arrays with estimated sizes_append_vec!helper for efficient vector/matrix appendingBenchmark Results
Before (1D diffusion, N=30):
After (1D diffusion, N=30):
The improvements are modest because most of the allocation overhead comes from symbolic manipulation in ModelingToolkit/Symbolics, which is outside the scope of this package. The changes here focus on the discretization pipeline itself.
Test Plan
Files Changed
src/discretization/generate_finite_difference_rules.jl- Optimized rule generationsrc/discretization/schemes/centered_difference/centered_difference.jl- Optimized cartesian rulessrc/scalar_discretization.jl- Optimized equation discretizationtest/runtests.jl- Added allocation test grouptest/alloc_tests.jl- New allocation regression testscc @ChrisRackauckas
🤖 Generated with Claude Code