chore(dev): tweak backend-memory-report

.github/scripts/backend-memory-report.mjs

@@ -287,10 +287,25 @@ function getHeapSnapshotCategoryValue(report, phase, category) {
 	return Number.isFinite(value) ? value : null;
 }
 
+function getHeapSnapshotBreakdownEntries(report, phase, category) {
+	const breakdown = report?.[phase]?.heapSnapshot?.breakdowns?.[category];
+	if (breakdown == null || typeof breakdown !== 'object') return [];
+
+	return Object.entries(breakdown)
+		.filter(([, value]) => Number.isFinite(value) && value > 0)
+		.toSorted((a, b) => b[1] - a[1]);
+}
+
 function escapeCsvValue(value) {
 	return `"${String(value).replaceAll('"', '""')}"`;
 }
 
+function formatSankeyValue(value) {
+	const rounded = Math.round(value * 100) / 100;
+	if (Number.isInteger(rounded)) return String(rounded);
+	return rounded.toFixed(2).replace(/0+$/, '').replace(/\.$/, '');
+}
+
 function renderHeapSnapshotSankey(report, phase, title) {
 	const total = getHeapSnapshotCategoryValue(report, phase, 'Total');
 	if (total == null || total <= 0) return null;
@@ -300,9 +315,13 @@ function renderHeapSnapshotSankey(report, phase, title) {
 		.map(category => {
 			const value = getHeapSnapshotCategoryValue(report, phase, category);
 			if (value == null || value <= 0) return null;
+			const breakdownEntries = getHeapSnapshotBreakdownEntries(report, phase, category);
+			const breakdownTotal = breakdownEntries.reduce((sum, [, childValue]) => sum + childValue, 0);
 			return {
 				category,
 				value,
+				breakdownTotal,
+				breakdownEntries,
 			};
 		})
 		.filter(value => value != null);
@@ -312,8 +331,13 @@ function renderHeapSnapshotSankey(report, phase, title) {
 	const nodeColors = {
 		[title]: heapSnapshotCategoriesColorsHex.Total,
 	};
-	for (const { category } of categories) {
-		nodeColors[category] = heapSnapshotCategoriesColorsHex[category];
+	for (const { category, breakdownEntries } of categories) {
+		const categoryColor = heapSnapshotCategoriesColorsHex[category] ?? heapSnapshotCategoriesColorsHex.Total;
+		nodeColors[category] = categoryColor;
+
+		for (const [childName] of breakdownEntries) {
+			nodeColors[`${category}: ${childName}`] = categoryColor;
+		}
 	}
 
 	const lines = [
@@ -327,11 +351,16 @@ function renderHeapSnapshotSankey(report, phase, title) {
 				nodeColors,
 			},
 		})}}%%`,
-		'sankey',
+		'sankey-beta',
 	];
 
-	for (const { category, value } of categories) {
-		lines.push(`${escapeCsvValue(title)},${escapeCsvValue(category)},${value}`);
+	for (const { category, value, breakdownTotal, breakdownEntries } of categories) {
+		lines.push(`${escapeCsvValue(title)},${escapeCsvValue(category)},${formatSankeyValue(value)}`);
+
+		for (const [childName, childValue] of breakdownEntries) {
+			const normalizedValue = breakdownTotal > 0 ? childValue * value / breakdownTotal : childValue;
+			lines.push(`${escapeCsvValue(category)},${escapeCsvValue(`${category}: ${childName}`)},${formatSankeyValue(normalizedValue)}`);
+		}
 	}
 
 	lines.push('```');
@@ -653,7 +682,7 @@ const head = JSON.parse(await readFile(headFile, 'utf8'));
 const baseJsFootprint = baseJsFootprintFile == null ? null : JSON.parse(await readFile(baseJsFootprintFile, 'utf8'));
 const headJsFootprint = headJsFootprintFile == null ? null : JSON.parse(await readFile(headJsFootprintFile, 'utf8'));
 const lines = [
-	'## Backend Memory Usage Report',
+	'## ⚙️ Backend Memory Usage Report',
 	'',
 ];
 

.github/scripts/measure-backend-memory-comparison.mjs

@@ -37,6 +37,8 @@ function readIntegerEnv(name, defaultValue, min) {
 	return value;
 }
 
+const HEAP_SNAPSHOT_BREAKDOWN_TOP_N = readIntegerEnv('MK_MEMORY_HEAP_SNAPSHOT_BREAKDOWN_TOP_N', 6, 1);
+
 function commandName(command) {
 	if (process.platform !== 'win32') return command;
 	if (command === 'pnpm') return 'pnpm.cmd';
@@ -111,6 +113,51 @@ function median(values) {
 	return Math.round((sorted[center - 1] + sorted[center]) / 2);
 }
 
+function summarizeHeapSnapshotBreakdowns(samples, phase) {
+	const breakdowns = {};
+
+	for (const category of heapSnapshotCategories) {
+		if (category === 'Total') continue;
+
+		const childKeys = new Set();
+		for (const sample of samples) {
+			for (const childKey of Object.keys(sample[phase]?.heapSnapshot?.breakdowns?.[category] ?? {})) {
+				childKeys.add(childKey);
+			}
+		}
+
+		const categoryBreakdown = {};
+		for (const childKey of childKeys) {
+			const values = samples
+				.map(sample => sample[phase]?.heapSnapshot?.breakdowns?.[category]?.[childKey])
+				.filter(value => Number.isFinite(value));
+
+			if (values.length > 0) categoryBreakdown[childKey] = median(values);
+		}
+
+		if (Object.keys(categoryBreakdown).length > 0) {
+			breakdowns[category] = collapseHeapSnapshotBreakdown(categoryBreakdown);
+		}
+	}
+
+	return breakdowns;
+}
+
+function collapseHeapSnapshotBreakdown(breakdown) {
+	const entries = Object.entries(breakdown)
+		.filter(([, value]) => value > 0)
+		.toSorted((a, b) => b[1] - a[1]);
+
+	const topEntries = entries.slice(0, HEAP_SNAPSHOT_BREAKDOWN_TOP_N);
+	const otherValue = entries
+		.slice(HEAP_SNAPSHOT_BREAKDOWN_TOP_N)
+		.reduce((sum, [, value]) => sum + value, 0);
+
+	const collapsed = Object.fromEntries(topEntries);
+	if (otherValue > 0) collapsed.Other = otherValue;
+	return collapsed;
+}
+
 function summarizeSamples(samples) {
 	const summary = {};
 
@@ -151,9 +198,12 @@ function summarizeSamples(samples) {
 		}
 
 		if (Object.keys(heapSnapshotCategoryValues).length > 0) {
+			const heapSnapshotBreakdowns = summarizeHeapSnapshotBreakdowns(samples, phase);
+
 			summary[phase].heapSnapshot = {
 				categories: heapSnapshotCategoryValues,
 				nodeCounts: heapSnapshotNodeCountValues,
+				...(Object.keys(heapSnapshotBreakdowns).length > 0 ? { breakdowns: heapSnapshotBreakdowns } : {}),
 			};
 		}
 	}