Antigravity Agent
129 lines
4.0 KiB
Markdown
129 lines
4.0 KiB
Markdown
---
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id: wiki-2026-0508-v8-javascript-engine
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title: V8 JavaScript Engine
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category: 10_Wiki/Topics
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status: verified
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canonical_id: self
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aliases: [V8, V8 Engine, Chrome V8]
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duplicate_of: none
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source_trust_level: A
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confidence_score: 0.9
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verification_status: applied
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tags: [v8, javascript, engine, runtime, chrome, node]
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raw_sources: []
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last_reinforced: 2026-05-10
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github_commit: pending
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tech_stack:
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language: C++
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framework: V8
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---
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# V8 JavaScript Engine
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## 매 한 줄
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> **"매 Ignition interpreter + TurboFan / Maglev / Sparkplug 의 매 multi-tier JIT 으로 매 JS 를 native 수준에 도달시키는 엔진"**. 매 Chrome / Edge / Node.js / Deno 의 핵심. 매 2026 기준 Maglev (mid-tier JIT) 와 매 pointer compression 으로 매 startup + memory 모두 개선됨.
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## 매 핵심
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### 매 Multi-tier compilation
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- **Ignition** — bytecode interpreter (fastest startup).
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- **Sparkplug** — non-optimizing baseline JIT (V8 9.1+).
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- **Maglev** — mid-tier optimizing JIT (V8 11.5+, default 11.9+).
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- **TurboFan** — top-tier optimizer (slow compile, fast run).
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### 매 Hidden classes & inline caches
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- 매 JS object 의 매 shape 추적 (V8 internal "Map").
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- 매 same-shape access 는 매 monomorphic IC 로 매 native 속도.
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- 매 shape 변경 (속성 추가 순서 다름) 매 → polymorphic / megamorphic.
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### 매 GC
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- Generational: young (scavenger, Minor MC) + old (Mark-Compact, Mark-Sweep).
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- Orinoco — concurrent / parallel / incremental.
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- Pointer compression (V8 8.0+) — 35-40% heap 절감.
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### 매 응용
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1. Browser JS — Chrome, Edge.
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2. Server JS — Node.js, Deno (V8 기반).
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3. Embedded — Electron, CEF.
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## 💻 패턴
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### Hidden class 친화적 객체
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```javascript
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// Good — same shape
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function User(id, name) { this.id = id; this.name = name; }
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// Bad — shape diverges
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function User(id, name) { this.id = id; if (name) this.name = name; }
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```
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### Monomorphic call site
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```javascript
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function getX(point) { return point.x; }
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// pass only one shape consistently → IC stays monomorphic
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const points = Array.from({ length: 1e6 }, (_, i) => ({ x: i, y: i }));
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points.forEach(getX);
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```
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### Avoiding deopt
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```javascript
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function add(a, b) { return a + b; }
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add(1, 2); // optimized for number
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add('a', 'b'); // deopt — TurboFan must reoptimize
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```
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### V8 inspector / profiling
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```bash
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node --inspect-brk app.js
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# Chrome devtools → Performance → JS samples
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```
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### V8 flags for diagnosis
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```bash
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node --trace-opt --trace-deopt app.js
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node --print-bytecode app.js
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node --allow-natives-syntax # %OptimizeFunctionOnNextCall
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```
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### Pointer compression check
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```bash
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node -p "process.config.variables.v8_enable_pointer_compression"
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# 1 → enabled
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```
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## 매 결정 기준
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| 관심사 | Approach |
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|---|---|
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| Startup 빠름 | Ignition / Sparkplug 충분 |
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| Hot loop | Maglev / TurboFan 의 monomorphic 유지 |
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| Memory tight | pointer compression + young GC tuning |
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| Diagnose perf | `--trace-deopt`, `clinic flame` |
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**기본값**: 매 modern V8 default — 매 micro-opt 보다 매 algorithmic 우선.
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## 🔗 Graph
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- 부모: [[JavaScript]] · [[JS Engine]]
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- 변형: [[JavaScriptCore]] · [[SpiderMonkey]] · [[Hermes]]
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- 응용: [[Node.js]] · [[Deno]] · [[Chrome]] · [[Electron]]
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- Adjacent: [[JIT Compilation]] · [[Garbage Collection]] · [[Inline Cache]]
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## 🤖 LLM 활용
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**언제**: 매 perf 분석 가설 세우기, 매 deopt 원인 추정.
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**언제 X**: 매 V8 internal 변경 빠름 — 매 매 latest blog 확인 필요.
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## ❌ 안티패턴
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- **Shape divergence**: 매 conditional property 추가 — 매 polymorphic 유발.
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- **delete 연산자**: 매 hidden class transition 강제.
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- **`arguments` 변형**: 매 deopt 유발.
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- **Try/catch in hot path**: 매 V8 ≤ 7.x 까진 deopt — 매 modern V8 은 ok 이나 매 case-by-case.
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## 🧪 검증 / 중복
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- Verified (V8 official blog v8.dev, "Maglev" announcement).
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- 신뢰도 A.
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## 🕓 Changelog
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| 날짜 | 변경 |
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|---|---|
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| 2026-05-08 | Phase 1 |
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| 2026-05-10 | Manual cleanup — Maglev + pointer compression 반영 |
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