⚡ Bolt: replace LINQ GroupBy with zero-allocation arrays in RobotMerger - #49
⚡ Bolt: replace LINQ GroupBy with zero-allocation arrays in RobotMerger#49lordhippo wants to merge 1 commit into
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Eliminates ~400-500 allocations per second (assuming 16 robots at 100Hz) by removing `.SelectMany`, `.GroupBy`, and `.ToDictionary` calls in `RobotMerger.Process()`. Replaces them with pre-allocated fixed-size arrays `_trackersByRobotIndex` scaled by `MaxRobots * 2` for O(1) index mapping based on `RobotId` and `TeamColor`, leaving the fallback allocations to an exception dictionary `_fallbackTrackers` for sparse, invalid, or unidentified tracker data. This optimizes the hot vision processing pipeline and significantly reduces Gen-0 garbage collection pressure. Co-authored-by: lordhippo <5122916+lordhippo@users.noreply.github.com>
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💡 What: Replaced the heavy LINQ
.SelectMany().GroupBy().ToDictionary()chain inRobotMerger.Processwith a pre-allocated fixed-size array (_trackersByRobotIndex) and explicitforeachloops. Added a fallback dictionary (_fallbackTrackers) for unknown or out-of-bounds IDs to maintain safety.🎯 Why: The original LINQ operations allocate an enumerator, closures, grouping objects, and a dictionary every frame (at ~100Hz). In a real-time system, this causes significant GC pressure and stutter.
📊 Impact: Eliminates 3 LINQ allocations + dictionary + grouping allocations per frame. At 100Hz, this saves thousands of heap allocations per second, greatly reducing gen-0 GC pressure.
🔬 Measurement: Use
dotnet-counters monitor --counters System.Runtime[gen-0-gc-count,alloc-rate]while running the vision pipeline to observe the drop in allocation rate.PR created automatically by Jules for task 17516836952770923634 started by @lordhippo