Performance Profiling

⚡ Performance Profiling

CPU, Memory profiling ve bottleneck analizi rehberi.

📋 İçindekiler

1. JavaScript/Node.js Profiling
2. React Profiling
3. Memory Leak Detection
4. Benchmark Teknikleri
5. Database Profiling

1. JavaScript/Node.js Profiling

Chrome DevTools

// Console timing
console.time('operation');
// ... code
console.timeEnd('operation');

// Performance API
const start = performance.now();
// ... code
const end = performance.now();
console.log(`Execution time: ${end - start}ms`);

Node.js Profiling

# CPU profiling
node --prof app.js
node --prof-process isolate-*.log > profile.txt

# Clinic.js (kapsamlı)
npx clinic doctor -- node app.js
npx clinic flame -- node app.js
npx clinic bubbleprof -- node app.js

V8 Profiler

const v8Profiler = require('v8-profiler-next');

v8Profiler.startProfiling('CPU');
// ... code
const profile = v8Profiler.stopProfiling('CPU');
profile.export((error, result) => {
  fs.writeFileSync('profile.cpuprofile', result);
  profile.delete();
});

2. React Profiling

React DevTools Profiler

import { Profiler } from 'react';

function onRenderCallback(
  id, phase, actualDuration, baseDuration, startTime, commitTime
) {
  console.log({ id, phase, actualDuration, baseDuration });
}

<Profiler id="MyComponent"
  <MyComponent />
</Profiler>

why-did-you-render

// wdyr.js
import React from 'react';
import whyDidYouRender from '@welldone-software/why-did-you-render';

whyDidYouRender(React, {
  trackAllPureComponents: true,
});

Render Optimization

// useMemo - hesaplama cache
const expensiveValue = useMemo(() => computeExpensive(a, b), [a, b]);

// useCallback - fonksiyon referans
const handleClick = useCallback(() => doSomething(id), [id]);

// React.memo - component memoization
const MemoizedComponent = React.memo(MyComponent);

3. Memory Leak Detection

Yaygın Leak Kaynakları

Chrome DevTools Memory Tab

1. Memory tab → Heap snapshot
2. Perform actions
3. Take another snapshot
4. Compare snapshots (Comparison view)
5. Filter by "Detached" for DOM leaks

Node.js Memory

# Memory usage monitoring
node --expose-gc app.js

# heapdump
npm install heapdump

const heapdump = require('heapdump');
heapdump.writeSnapshot('./heap-' + Date.now() + '.heapsnapshot');

4. Benchmark Teknikleri

JavaScript Benchmarking

// Benchmark.js
const Benchmark = require('benchmark');
const suite = new Benchmark.Suite;

suite
  .add('Method A', () => methodA())
  .add('Method B', () => methodB())
  .on('cycle', (event) => console.log(String(event.target)))
  .on('complete', function() {
    console.log('Fastest: ' + this.filter('fastest').map('name'));
  })
  .run({ async: true });

HTTP Benchmarking

# autocannon (Node.js)
npx autocannon -c 100 -d 30 http://localhost:3000

# wrk
wrk -t12 -c400 -d30s http://localhost:3000

# ab (Apache Bench)
ab -n 10000 -c 100 http://localhost:3000/

Lighthouse CI

npx lhci autorun --collect.url=http://localhost:3000

5. Database Profiling

PostgreSQL

-- Slow query log
ALTER SYSTEM SET log_min_duration_statement = 1000; -- 1s

-- EXPLAIN ANALYZE
EXPLAIN (ANALYZE, BUFFERS, FORMAT TEXT)
SELECT * FROM users WHERE email = 'test@example.com';

-- pg_stat_statements
SELECT query, calls, mean_time, total_time
FROM pg_stat_statements
ORDER BY total_time DESC
LIMIT 10;

MongoDB

// Profiling enable
db.setProfilingLevel(1, { slowms: 100 });

// Query profiler
db.system.profile.find().sort({ ts: -1 }).limit(10);

// Explain
db.users.find({ email: "test@example.com" }).explain("executionStats");

🎯 Quick Performance Checklist

- [ ] Bundle size analizi (webpack-bundle-analyzer)
- [ ] Core Web Vitals (LCP, FID, CLS)
- [ ] Network waterfall analizi
- [ ] Memory leak kontrolü
- [ ] Database query optimization
- [ ] Caching stratejisi (Redis, CDN)
- [ ] Code splitting / Lazy loading

Performance Profiling v1.1 - Enhanced

🔄 Workflow

Kaynak: Chrome DevTools Performance Features & Node.js Diagnostics

Aşama 1: Capture

• Tool Selection: CPU yoğun işler için Node --prof veya py-spy, Frontend için Chrome DevTools.
• Environment: Profiling işlemini mümkünse Prod-like bir ortamda, değilse Prod'da (Sampling profiler ile) yap.
• Recording: Yeterli veri toplamak için en az 30-60 saniye kayıt al.

Aşama 2: Analysis (Flamegraph)

• Width: Grafikte geniş yer kaplayan bloklar (Zaman harcayan fonksiyonlar) hedeftir.
• Depth: Derin stack'ler genellikle recursion veya karmaşık framework çağrılarını gösterir.
• Hot Path: En sık çağrılan ve toplam süresi en yüksek olan fonksiyonu bul.

Aşama 3: Optimization & Verification

• De-optimization: V8 (JS) optimizasyonunu bozan pattern'leri (Örn: delete keyword, hidden class changes) temizle.
• Memory: Garbage Collection (Minor/Major GC) sıklığını kontrol et. Çok sık GC = Memory thrashing.
• Verify: Düzeltme sonrası tekrar profil alıp farkı kanıtla.

Kontrol Noktaları