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1fbcf0f | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 | #!/usr/bin/env node
// Chrome Performance Trace Analyzer — outputs a compact summary
// Usage: node analyze-trace.js <trace.json>
const fs = require('fs')
const path = require('path')
const file = process.argv[2]
if (!file) { console.error('Usage: node analyze-trace.js <trace.json>'); process.exit(1) }
console.log(`Reading ${path.basename(file)} (${(fs.statSync(file).size / 1e6).toFixed(1)} MB)...`)
const raw = fs.readFileSync(file, 'utf8')
console.log('Parsing...')
const trace = JSON.parse(raw)
const events = Array.isArray(trace) ? trace : (trace.traceEvents || [])
console.log(`Total events: ${events.length.toLocaleString()}\n`)
// ── 1. Long Tasks (> 50ms on main thread) ────────────────────────────────────
const LONG_TASK_MS = 50
const tasks = events
.filter(e => e.ph === 'X' && e.dur && e.dur > LONG_TASK_MS * 1000)
.sort((a, b) => b.dur - a.dur)
.slice(0, 30)
console.log(`═══ TOP LONG TASKS (>${LONG_TASK_MS}ms) ═══`)
for (const t of tasks) {
const ms = (t.dur / 1000).toFixed(1)
const name = t.name || '(unknown)'
const cat = t.cat || ''
console.log(` ${ms.padStart(8)}ms ${name} [${cat}]`)
}
// ── 2. Summarise all complete events by name ──────────────────────────────────
const byName = new Map()
for (const e of events) {
if (e.ph !== 'X' || !e.dur) continue
const key = e.name
const existing = byName.get(key)
if (existing) {
existing.totalMs += e.dur / 1000
existing.count++
if (e.dur > existing.maxMs * 1000) existing.maxMs = e.dur / 1000
} else {
byName.set(key, { totalMs: e.dur / 1000, count: 1, maxMs: e.dur / 1000 })
}
}
const topByTotal = [...byName.entries()]
.sort((a, b) => b[1].totalMs - a[1].totalMs)
.slice(0, 40)
console.log('\n═══ TOP EVENTS BY TOTAL TIME ═══')
console.log(' Total(ms) Max(ms) Count Name')
for (const [name, s] of topByTotal) {
console.log(
` ${s.totalMs.toFixed(1).padStart(9)} ${s.maxMs.toFixed(1).padStart(7)} ${String(s.count).padStart(5)} ${name}`
)
}
// ── 3. React-specific events ──────────────────────────────────────────────────
const reactKeywords = ['react', 'React', 'setState', 'useState', 'useMemo', 'useEffect',
'reconcil', 'Reconcil', 'render', 'Render', 'commit', 'Commit', 'fiber', 'Fiber',
'Marker', 'MapView', 'photoUrl', 'createPlace', 'markers']
const reactEvents = [...byName.entries()]
.filter(([name]) => reactKeywords.some(k => name.includes(k)))
.sort((a, b) => b[1].totalMs - a[1].totalMs)
.slice(0, 30)
if (reactEvents.length > 0) {
console.log('\n═══ REACT / MAP EVENTS ═══')
for (const [name, s] of reactEvents) {
console.log(` ${s.totalMs.toFixed(1).padStart(9)}ms total ${s.maxMs.toFixed(1).padStart(7)}ms max ${s.count}x ${name}`)
}
}
// ── 4. V8 / JS heavy hitters ─────────────────────────────────────────────────
const jsEvents = [...byName.entries()]
.filter(([, s]) => s.totalMs > 20)
.filter(([name]) => {
const cat = (events.find(e => e.name === name)?.cat || '')
return cat.includes('v8') || cat.includes('devtools.timeline') || name.includes('JS') || name.includes('Compile') || name.includes('GC')
})
.sort((a, b) => b[1].totalMs - a[1].totalMs)
.slice(0, 20)
if (jsEvents.length > 0) {
console.log('\n═══ V8 / JS EVENTS (>20ms total) ═══')
for (const [name, s] of jsEvents) {
console.log(` ${s.totalMs.toFixed(1).padStart(9)}ms ${s.count}x ${name}`)
}
}
// ── 5. CPU profile — top self-time functions ─────────────────────────────────
const profileChunks = events.filter(e => e.name === 'ProfileChunk')
if (profileChunks.length > 0) {
const selfTime = new Map()
for (const chunk of profileChunks) {
const nodes = chunk.args?.data?.cpuProfile?.nodes || []
const samples = chunk.args?.data?.cpuProfile?.samples || []
const timeDeltas = chunk.args?.data?.timeDeltas || []
// Build node map
const nodeMap = new Map(nodes.map(n => [n.id, n]))
// Accumulate self time per node
for (let i = 0; i < samples.length; i++) {
const nodeId = samples[i]
const dt = (timeDeltas[i] || 0) / 1000 // µs → ms
const node = nodeMap.get(nodeId)
if (!node) continue
const fn = node.callFrame?.functionName || '(anonymous)'
const url = node.callFrame?.url || ''
const line = node.callFrame?.lineNumber || 0
const key = `${fn} @ ${url.split('/').slice(-2).join('/')}:${line}`
selfTime.set(key, (selfTime.get(key) || 0) + dt)
}
}
const topSelf = [...selfTime.entries()]
.sort((a, b) => b[1] - a[1])
.slice(0, 40)
console.log('\n═══ CPU PROFILE — TOP SELF-TIME FUNCTIONS ═══')
for (const [name, ms] of topSelf) {
console.log(` ${ms.toFixed(1).padStart(8)}ms ${name}`)
}
}
// ── 6. Paint / Layout costs ───────────────────────────────────────────────────
const renderCats = ['Layout', 'UpdateLayoutTree', 'Paint', 'CompositeLayers', 'RasterTask']
console.log('\n═══ RENDERING COSTS ═══')
for (const cat of renderCats) {
const s = byName.get(cat)
if (s) console.log(` ${s.totalMs.toFixed(1).padStart(9)}ms total ${s.maxMs.toFixed(1).padStart(7)}ms max ${s.count}x ${cat}`)
}
console.log('\nDone.')
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