"done" callback cause memory leak

I am trying to wrap “env” in Promise, but memory grows heavily in production.

Below code shows no memory leaks. If replacing the no leaks with the leaking code, Window object would not be GCed.

In addition, uncomment injecting jquery source causes it always leaks.

All are tested and use chrome profiles to investigate.

import * as jsdom from "jsdom";
import * as fs from "fs";
import * as _ from "lodash";
var heapdump = require('heapdump');

var jquery = fs.readFileSync("assets/jquery.min.js", "utf-8");

function envAsync() {
    return new Promise<Window>(function (resolve, reject) {
        jsdom.env({
            html: "https://www.google.com/?gws_rd=ssl",
            // always leak if uncomment
            //src: [jquery],
            done: function (err, window) {
                if (err) {
                    return reject(err);
                }

                // no leaks version
                window.close();
                resolve(null);

                // memory leaking version
                // resolve(window);
            }
        });
    });
}

heapdump.writeSnapshot(function (err, sname) {
    console.log(sname);

    (async () => {
        for (var index = 0; index < 10; index++) {
            var window = await envAsync();

            // memory leaking version
            // window.close();
        }

        setTimeout(function () {
            global.gc();
            heapdump.writeSnapshot(function (err, ename) {
                console.log(ename);
            });
        }, 5000);
    })();
});

the figure shows 4 Window instances, but there are hundreds in my actual app.

this one is no leaking version

[domenic]

There have also been some great fixes in vm memory usage in Node v6; you should see if upgrading fixes the issue.

[Sebmaster]

Your testing code is wrong I think. There’ll be at least 1 window around because you save your window with a var which is still referenced when the GC runs (because function scoping). If google has a frame somewhere, that might explain the additional instances (although I’m not sure about that).