---
id: wiki-2026-0508-analyze-runtime-performance
title: Analyze runtime performance
category: 10_Wiki/Topics
status: verified
canonical_id: self
aliases: [Performance Analysis, Profiling, Runtime Profiling]
duplicate_of: none
source_trust_level: A
confidence_score: 0.9
verification_status: applied
tags: [profiling, performance, devtools]
raw_sources: []
last_reinforced: 2026-05-10
github_commit: applied
tech_stack:
  language: JavaScript/Python
  framework: Chrome DevTools/perf/py-spy
---

# Analyze runtime performance

## 매 한 줄
> **"매 측정 없이 최적화 없다."**. Runtime performance 분석은 sampling profiler + tracing + flame graph + RAIL/Web Vitals metrics 의 stack 으로 매 hot path 와 long task 를 식별. 2026 stack: Chrome Performance panel (Insights AI), perf+FlameGraph, py-spy, eBPF/bpftrace, Datadog APM.

## 매 핵심

### 매 Profiler Type
- **Sampling**: 매 N ms 마다 stack 캡처 — 매 low overhead, statistical (perf, py-spy, async-profiler).
- **Instrumentation**: 매 fn enter/exit 기록 — 매 accurate, high overhead.
- **Tracing**: 매 event timeline (Chrome trace, perfetto).
- **Hardware counters**: PMU — IPC, cache miss, branch miss.

### 매 RAIL Model (web)
- **Response**: < 100ms input → feedback.
- **Animation**: < 16ms / frame (60fps).
- **Idle**: 50ms work blocks max.
- **Load**: < 5s on 4G.

### 매 Core Web Vitals 2026
- **LCP** (Largest Contentful Paint) < 2.5s.
- **INP** (Interaction to Next Paint) < 200ms — 매 FID 대체 (2024+).
- **CLS** (Cumulative Layout Shift) < 0.1.

### 매 응용
1. Web app TTI/INP 개선.
2. Backend p99 latency 추적.
3. Game/XR frame budget.
4. ML inference latency.
5. CI pipeline 시간 단축.

## 💻 패턴

### Chrome Performance panel + AI insights
```javascript
// 매 manual marker — show up in Performance timeline
performance.mark('ai-search:start');
const r = await search(q);
performance.mark('ai-search:end');
performance.measure('ai-search', 'ai-search:start', 'ai-search:end');
// 매 record trace in DevTools → AI Insights highlights bottleneck (2025+)
```

### User Timing API + reporter
```javascript
const obs = new PerformanceObserver(list => {
  list.getEntries().forEach(e => analytics('perf', { name: e.name, dur: e.duration }));
});
obs.observe({ entryTypes: ['measure', 'navigation', 'resource', 'longtask'] });
```

### py-spy live flame graph
```bash
# 매 attach to running PID, no code change
py-spy record -o flame.svg --pid 12345 --duration 30
# 매 live top-like
py-spy top --pid 12345
```

### Linux perf flame graph
```bash
sudo perf record -F 99 -g -p $PID -- sleep 30
sudo perf script | \
  ./stackcollapse-perf.pl | ./flamegraph.pl > flame.svg
```

### Web Vitals INP measurement
```javascript
import { onINP, onLCP, onCLS } from 'web-vitals';
onINP(m => beacon('inp', m.value, m.id));
onLCP(m => beacon('lcp', m.value, m.id));
onCLS(m => beacon('cls', m.value, m.id));
```

### Node --prof + --prof-process
```bash
node --prof server.js
# 매 after run
node --prof-process isolate-*.log > profile.txt
```

### eBPF (bpftrace) syscall latency
```bash
sudo bpftrace -e '
  tracepoint:syscalls:sys_enter_read { @s[tid] = nsecs; }
  tracepoint:syscalls:sys_exit_read /@s[tid]/ {
    @us = hist((nsecs - @s[tid]) / 1000);
    delete(@s[tid]);
  }'
```

## 매 결정 기준
| 상황 | Tool |
|---|---|
| Web (Chromium) | DevTools Performance + Web Vitals |
| Node.js | clinic.js / 0x / --prof |
| Python | py-spy / scalene / cProfile |
| JVM | async-profiler / JFR |
| Go | pprof |
| Linux native | perf + FlameGraph / eBPF |
| Production APM | Datadog / NewRelic / OTel |

**기본값**: 매 sampling profiler 우선, instrumentation 은 spot-check.

## 🔗 Graph
- 부모: [[Flame_Graphs]]
- 변형: [[CPU Bottleneck]]
- 응용: [[High Resolution Time]] · [[Memory Management]]
- Adjacent: [[Page Experience Algorithm]] · [[Debugger_Techniques]]

## 🤖 LLM 활용
**언제**: flame graph 해석, perf insight 요약, regression hypothesis.
**언제 X**: 매 nanosecond-level profiling — specialized tool 만이 정확.

## ❌ 안티패턴
- **Production 에 instrumenting profiler**: 매 overhead 폭발.
- **Single-run 결론**: 매 statistical noise — multi-run 필요.
- **Average only**: 매 p50 보다 p99 가 user 체감.
- **Profile dev build**: 매 prod build 와 다름 — release/optimized 측정.

## 🧪 검증 / 중복
- Verified: web.dev Performance docs; Brendan Gregg "Systems Performance"; Chrome DevTools docs.
- 신뢰도 A.

## 🕓 Changelog
| 날짜 | 변경 |
|---|---|
| 2026-05-08 | Phase 1 |
| 2026-05-10 | Manual cleanup — RAIL/INP + multi-language profilers |