Memory leak with fetching external sources

It seems that externally fetched sources (like js-files) are not properly cleared from memory:

var jsdom = require('jsdom');

function get() {
  return new Promise((resolve, reject) => {
    jsdom.env({
      url: 'http://localhost:3200/some-page-with-js',
      features: {
        FetchExternalResources: ['script'],
        ProcessExternalResources: ['script'],
      },
      done: (err, window) => {
        if (err) {
          reject(err);
        } else {
          window.close();
          resolve();
        }
      },
    });
  });
}

function recurse(i) {
  console.log('recurse', i);
  if (i < 10000) {
    get().then(x => recurse(i+1));
  }
}

recurse(0);

<--- Last few GCs --->

   40573 ms: Mark-sweep 1336.1 (1447.4) -> 1337.8 (1447.4) MB, 787.7 / 0 ms [allocation failure] [GC in old space requested].
   41390 ms: Mark-sweep 1337.8 (1447.4) -> 1337.8 (1447.4) MB, 816.4 / 0 ms [allocation failure] [GC in old space requested].
   42260 ms: Mark-sweep 1337.8 (1447.4) -> 1287.9 (1447.4) MB, 869.9 / 0 ms [last resort gc].
   43173 ms: Mark-sweep 1287.9 (1447.4) -> 1334.9 (1447.4) MB, 913.7 / 0 ms [last resort gc].


<--- JS stacktrace --->

==== JS stack trace =========================================

Security context: 0x2a6aadc44a49 <JS Object>
    2: runInContext [vm.js:~42] [pc=0x361d28a9b004] (this=0x2a7ae5198239 <an Object with map 0xb6831c271a9>,code=0xf882304101 <Very long string[4912697]>,contextifiedSandbox=0x31599489d4e9 <a Window with map 0x3e12b0c06bf9>,options=0x1947d74ae761 <an Object with map 0xb6831c3e1d1>)
    3: processJavaScript(aka processJavaScript) [/Users/Jasper/Code/Q42/blink/test/functional/node_modules/jsdom/l...

FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - process out of memory

[thymikee]

I’d like to bump this thread, since I think this is something more generic as it happens also for jsdom.jsdom() method. I’ve setup a basic repro with the issue: https://github.com/thymikee/jsdom-leak-repro. Hope it helps someone familiar with jsdom internals to see what’s going on.

Below code is sufficient to retain the Window object:

const jsdom = require('jsdom');
const toMB = bytes => Math.floor(bytes / 1024 / 1024);

function spawnWindow(index) {
  let document = jsdom.jsdom({ url: 'about:blank' });
  let window = document.defaultView;
  const bytes = process.memoryUsage().heapUsed;

  console.log(index, `(${toMB(bytes)} MB)`);

  window.close();
  global.gc(); // force GC to isolate the leak
}

for (let i = 0; i < 200; i++) {
  spawnWindow(i);
}

This is actual problem that we sometimes experience at Jest, here’s on of the relevant issues: https://github.com/facebook/jest/issues/1893

[alecc08]

I have the same issue, going over 1.5GB of memory after about 30 iterations of loading a page, even when calling window.close() after each page load. Also happened when I disabled loading externalResources so I don’t think that’s the issue