client.destroy() does not clean up everything

[lacker]

Using:
webtorrent@0.103.0
Ubuntu 18.04.2 LTS
Node v8.10.0

This code creates a client, download one torrent, then attempts to shut down the client cleanly:

const WebTorrent = require("webtorrent-hybrid");

const SAMPLESITE =
  "magnet:?xt=urn:btih:e60f82343019bd711c5c731b46e118b0f2b2ecc6&dn=samplesite&tr=ws%3A%2F%2Flocalhost%3A4444&tr=wss%3A%2F%2Ftracker.btorrent.xyz&tr=wss%3A%2F%2Ftracker.fastcast.nz&tr=wss%3A%2F%2Ftracker.openwebtorrent.com";

let client = new WebTorrent();
let info = SAMPLESITE;
console.log("adding", info);
client.add(info, torrent => {
  for (let file of torrent.files) {
    console.log("file:", file.name);
  }
  torrent.on("done", () => {
    console.log("downloaded", torrent.downloaded, "bytes");
    console.log("shutting down");
    client.destroy(err => {
      console.log("error:", err);
      console.log("shutdown allegedly complete");
    });
  });
});

When I run this, the download succeeds, all callbacks run, and there is no error, but the node process does not close, indicating that destroy is leaving something open.

I ran it from within wtfnode to debug, and it shows a bunch of open timer handles from the simple-peer library:

- Timers:
  - (5000 ~ 5 s) (anonymous) @ /home/lacker/js/node_modules/simple-peer/index.js:544
  - (5000 ~ 5 s) (anonymous) @ /home/lacker/js/node_modules/simple-peer/index.js:544
  - (5000 ~ 5 s) (anonymous) @ /home/lacker/js/node_modules/simple-peer/index.js:544
  - (5000 ~ 5 s) (anonymous) @ /home/lacker/js/node_modules/simple-peer/index.js:544
  - (5000 ~ 5 s) (anonymous) @ /home/lacker/js/node_modules/simple-peer/index.js:544
  - (5000 ~ 5 s) (anonymous) @ /home/lacker/js/node_modules/simple-peer/index.js:544
  - (5000 ~ 5 s) (anonymous) @ /home/lacker/js/node_modules/simple-peer/index.js:544
  - (5000 ~ 5 s) (anonymous) @ /home/lacker/js/node_modules/simple-peer/index.js:544
  - (5000 ~ 5 s) (anonymous) @ /home/lacker/js/node_modules/simple-peer/index.js:544
  - (5000 ~ 5 s) (anonymous) @ /home/lacker/js/node_modules/simple-peer/index.js:544

[lacker]

I debugged this some more. Although it doesn't clean up everything immediately, the only remaining handles are timers that will eventually go off and leave nothing open. So it does clean up within 5 seconds, which I'm guessing is "working sufficiently well as intended". I'll close this issue