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| 1 | +/** |
| 2 | + * @license |
| 3 | + * Copyright 2025 Google LLC |
| 4 | + * SPDX-License-Identifier: Apache-2.0 |
| 5 | + */ |
| 6 | + |
| 7 | +import * as fs from 'node:fs'; |
| 8 | + |
| 9 | +function parseSnapshot(filePath) { |
| 10 | + console.log(`Loading ${filePath}...`); |
| 11 | + const data = JSON.parse(fs.readFileSync(filePath, 'utf8')); |
| 12 | + const strings = data.strings; |
| 13 | + const nodes = data.nodes; |
| 14 | + const nodeFields = data.snapshot.meta.node_fields; |
| 15 | + const nodeFieldCount = nodeFields.length; |
| 16 | + |
| 17 | + const typeOffset = nodeFields.indexOf('type'); |
| 18 | + const nameOffset = nodeFields.indexOf('name'); |
| 19 | + const sizeOffset = nodeFields.indexOf('self_size'); |
| 20 | + |
| 21 | + const nodeTypes = data.snapshot.meta.node_types[typeOffset]; |
| 22 | + |
| 23 | + const counts = {}; |
| 24 | + const sizes = {}; |
| 25 | + |
| 26 | + for (let i = 0; i < nodes.length; i += nodeFieldCount) { |
| 27 | + const typeIdx = nodes[i + typeOffset]; |
| 28 | + const typeName = nodeTypes[typeIdx]; |
| 29 | + const nameIdx = nodes[i + nameOffset]; |
| 30 | + const name = typeof nameIdx === 'number' ? strings[nameIdx] : nameIdx; |
| 31 | + const size = nodes[i + sizeOffset]; |
| 32 | + |
| 33 | + // Ignore native primitives/arrays that clutter the output unless specifically looking for them |
| 34 | + if ( |
| 35 | + typeName === 'string' || |
| 36 | + typeName === 'number' || |
| 37 | + typeName === 'array' |
| 38 | + ) { |
| 39 | + continue; |
| 40 | + } |
| 41 | + |
| 42 | + const key = `${typeName}::${name}`; |
| 43 | + counts[key] = (counts[key] || 0) + 1; |
| 44 | + sizes[key] = (sizes[key] || 0) + size; |
| 45 | + } |
| 46 | + return {counts, sizes}; |
| 47 | +} |
| 48 | + |
| 49 | +const [, , file1, file2] = process.argv; |
| 50 | +if (!file1 || !file2) { |
| 51 | + console.error( |
| 52 | + 'Usage: node compare_snapshots.js <baseline.heapsnapshot> <target.heapsnapshot>', |
| 53 | + ); |
| 54 | + process.exit(1); |
| 55 | +} |
| 56 | + |
| 57 | +try { |
| 58 | + const snap1 = parseSnapshot(file1); |
| 59 | + const snap2 = parseSnapshot(file2); |
| 60 | + |
| 61 | + const diffs = []; |
| 62 | + for (const key in snap2.counts) { |
| 63 | + const count1 = snap1.counts[key] || 0; |
| 64 | + const count2 = snap2.counts[key]; |
| 65 | + const size1 = snap1.sizes[key] || 0; |
| 66 | + const size2 = snap2.sizes[key]; |
| 67 | + |
| 68 | + if (count2 > count1) { |
| 69 | + diffs.push({ |
| 70 | + key, |
| 71 | + countDiff: count2 - count1, |
| 72 | + sizeDiff: size2 - size1, |
| 73 | + }); |
| 74 | + } |
| 75 | + } |
| 76 | + |
| 77 | + diffs.sort((a, b) => b.sizeDiff - a.sizeDiff); |
| 78 | + |
| 79 | + console.log('\n--- Top 10 growing objects by size ---'); |
| 80 | + diffs.slice(0, 10).forEach(d => { |
| 81 | + console.log(`${d.key}: +${d.countDiff} objects, +${d.sizeDiff} bytes`); |
| 82 | + }); |
| 83 | + |
| 84 | + // Look for common leak indicators |
| 85 | + const commonLeaks = diffs.filter( |
| 86 | + d => |
| 87 | + d.key.toLowerCase().includes('detached') || |
| 88 | + d.key.toLowerCase().includes('html') || |
| 89 | + d.key.toLowerCase().includes('eventlistener') || |
| 90 | + d.key.toLowerCase().includes('context') || |
| 91 | + d.key.toLowerCase().includes('closure'), |
| 92 | + ); |
| 93 | + |
| 94 | + commonLeaks.sort((a, b) => b.countDiff - a.countDiff); |
| 95 | + |
| 96 | + console.log('\n--- Top 3 most common types of memory leaks found ---'); |
| 97 | + if (commonLeaks.length === 0) { |
| 98 | + console.log('No common DOM or Closure leaks detected.'); |
| 99 | + } else { |
| 100 | + commonLeaks.slice(0, 3).forEach(d => { |
| 101 | + console.log(`${d.key}: +${d.countDiff} objects, +${d.sizeDiff} bytes`); |
| 102 | + }); |
| 103 | + } |
| 104 | +} catch (error) { |
| 105 | + console.error( |
| 106 | + 'Error parsing snapshots. They might be too large for JSON.parse or invalid.', |
| 107 | + ); |
| 108 | + console.error(error.message); |
| 109 | +} |
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