memlab

memlab

memlab is an E2E testing and analysis framework for finding memory leaks in-browser JavaScript Code. The CLI Toolbox and library provide extensible interfaces for analyzing heap snapshots taken from Chrome, Node.js, Hermes, and Electron.js.

CLI Usage

Install the CLI

npm install -g @memlab

To find memory leaks in Google Maps, create a scenario file defining how we want to interact with the Google Maps, let's name it test-google-maps.js:

// Visit Google Maps
function url() {
  return 'https://www.google.com/maps/@37.386427,-122.0428214,11z';
}

// action where we want to detect memory leaks: click the Hotels button
async function action(page) {
  await page.click('button[aria-label="Hotels"]');
}

// action where we want to go back to the step before: click clear search
async function back(page) {
  await page.click('[aria-label="Clear search"]');
}

module.exports = {action, back, url};

Now run memlab with the scenario file, memlab will interaction with the web page and show detected memory leaks:

memlab run --scenario test-google-maps.js

View which object keeps growing in size during interaction in the previous run:

memlab analyze unbound-object

Analyze pre-fetched v8/hermes .heapsnapshot files:

memlab analyze unbound-object --snapshot-dir <DIR_OF_SNAPSHOT_FILES>

Use memlab analyze to view all memory analyses. For extension, view the doc site.

View retain trace of a particular object:

memlab report --nodeId <HEAP_OBJECT_ID>

Use memlab help to view all CLI commands.

APIs

Use the memlab library to start a E2E run in browser and detect memory leaks.

const memlab = require('memlab');

const scenario = {
    // initial page load url
    url: () => 'https://www.google.com/maps/@37.386427,-122.0428214,11z',

    // action where we want to detect memory leaks
    action: async (page) => await page.click('button[aria-label="Hotels"]'),

    // action where we want to go back to the step before
    back: async (page) => await page.click('[aria-label="Clear search"]'),
}
memlab.run({scenario});