--- name: dev-patterns-object-pooling description: Object pooling for high-performance R3F components (decals, particles, projectiles) category: patterns --- # Object Pooling Pattern > "Pre-allocate, reuse, recycle – eliminate runtime GC pauses." ## When to Use This Skill Use when: - Creating/destroying objects every frame (bullets, particles, decals) - Targeting 60 FPS with many transient objects - Seeing GC pauses in Chrome DevTools Performance tab - Objects have identical initialization (can be pre-created) - Maximum simultaneous objects is bounded (~500 or less) ## Quick Start ```tsx // Basic object pool pattern const POOL_SIZE = 500; const MAX_ACTIVE = 200; interface PoolSlot { obj: T; active: boolean; lastUsed: number; } function useObjectPool( create: () => T, activate: (obj: T) => void, deactivate: (obj: T) => void ) { const poolRef = useRef[]>([]); // Initialize pool on mount useEffect(() => { poolRef.current = Array.from({ length: POOL_SIZE }, () => ({ obj: create(), active: false, lastUsed: 0, })); return () => { // Cleanup poolRef.current.forEach(slot => { if (slot.obj?.dispose) slot.obj.dispose(); }); }; }, []); const acquire = useCallback(() => { const pool = poolRef.current; // Find inactive slot let slot = pool.find(s => !s.active); // If pool full, recycle LRU if (!slot) { slot = pool.reduce((oldest, s) => s.lastUsed < oldest.lastUsed ? s : oldest ); deactivate(slot.obj); } slot.active = true; slot.lastUsed = performance.now(); activate(slot.obj); return slot.obj; }, [activate]); const release = useCallback((obj: T) => { const slot = poolRef.current.find(s => s.obj === obj); if (slot) slot.active = false; }, []); return { acquire, release }; } ``` ## Decision Framework | Scenario | Use Pool? | Reason | | ---------------------------- | --------- | -------------------------- | | Bullets (max ~100 active) | Yes | High create/destroy rate | | Decals (max ~200 visible) | Yes | Geometry allocation costly | | Particles (max ~500) | Yes | Per-frame creation | | UI overlays (dynamic count) | No | Unpredictable count | | Player characters (1-32) | No | Low churn, complex init | | Static props | No | Never destroyed | ## LRU Eviction Pattern When the pool is full, evict the **Least Recently Used** item: ```tsx // LRU recycling let slot = pool.find(s => !s.active); if (!slot) { // Pool exhausted - recycle oldest decal slot = pool.reduce((oldest, s) => s.lastUsed < oldest.lastUsed ? s : oldest ); // Fade out before recycling fadeOutDecal(slot.obj); } ``` **Why LRU?** - Predictable: older content fades first (less noticeable) - Fair: no single hot-spot gets preferential treatment - Simple: O(n) scan is fine for pools < 1000 ## GC-Avoidance: Temp Vector Reuse ```tsx // BAD: Creates new objects every frame useFrame(() => { const position = new Vector3(); const quaternion = new Quaternion(); // ... do work }); // GOOD: Reuse temp objects const _tempVec = useRef(new Vector3()).current; const _tempQuat = useRef(new Quaternion()).current; useFrame(() => { _tempVec.set(0, 0, 0); // Reset, don't reallocate _tempQuat.identity(); // ... do work }); ``` ## Pool Size Guidelines | Object Type | Suggested Pool Size | Max Active | Rationale | | ------------- | ------------------- | ---------- | ----------------------------------- | | Bullets | 200 | 100 | Fast fire rate ~10/sec | | Particles | 1000 | 500 | Explosions spawn many at once | | Decals | 500 | 200 | Persist 60s, but limited visibility | | Audio sources | 32 | 16 | WebAudio limit | **Rule of thumb:** `poolSize = maxActive * 2` to `maxActive * 3` ## Implementation Checklist - [ ] Pre-create all objects on mount (useEffect) - [ ] Use `active` flag to track in-use slots - [ ] Use `lastUsed` timestamp for LRU eviction - [ ] Properly dispose geometries/materials in cleanup - [ ] Reuse temp vectors with `useRef` or class fields - [ ] Initialize materials per-slot (not shared) when needed - [ ] Consider `frustumCulled={false}` for small objects ## Common Pitfalls | Pitfall | Symptom | Fix | | ------------------------------ | -------------------- | -------------------------------- | | Sharing material across slots | All decals same color| Create unique material per slot | | Forgetting to reset state | Stale data on reuse | Reset all props in activate() | | Pool too small | Visible popping | Increase pool or maxActive | | No disposal in useEffect | Memory leak | Add cleanup function | | Using `new` in useFrame | GC stutter | Use temp refs | ## Reference Implementation See: `src/components/game/effects/PaintDecalManager.tsx` Key sections: - Pool initialization: lines 68-118 - Acquire/activate: lines 120-141 - LRU recycling: lines 142-153 - Release/deactivate: lines 155-162 - Temp vector reuse: lines 35-37 --- Source attribution: feliperyba Original project: https://github.com/feliperyba/ralph-orchestra/blob/7a74951367fe9bec093753f6eaa4d0eeda9428e5/.claude/skills/dev-patterns-object-pooling/SKILL.md License: MIT License information: https://opensource.org/license/mit Original upstream instructions; downloaded from Dave AI. ## Upstream license notice MIT License Copyright (c) 2026 feliperyba Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. 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