discord.js: Possible memory leak in StreamDispatcher

Please describe the problem you are having in as much detail as possible: The bot is continuously (every X seconds) streaming a different Youtube video with a random seek to a voice channel. The memory (heap size) keeps increasing as time goes on.

I don’t understand much about memory/heap, but these are some heap snapshots I made with the node inspector, the last snapshot is 30 minutes in. The actual memory on my pc is larger when you count all the node processes.

What I think keeps allocating high ‘retained size’ are ArrayBuffer and Buffer, a lot of them with references to StreamDispatcher.js, VolumeTransformer.js, _stream_readable.js etc.

This is the ‘size delta’ on another run I did:

I think it has to do with me ending the dispatcher before the stream is finished and/or me seeking to a certain part of the video and then ending the dispatcher. I also tried this however without the seek option, and it shows the same result. Hopefully someone can point out something I’m missing.

Include a reproducible code sample here, if possible: I made a simple re-producible sample which I run in a single guild with 1 member. Say “!start” once you are in a voice channel. https://github.com/seuuuul/example

import { Client, Message, VoiceChannel } from "discord.js";
import ytdl from "ytdl-core";

const TOKEN = "token";
const YOUTUBE_LINKS = [
  "https://youtu.be/FzVR_fymZw4",
  "https://youtu.be/9pdj4iJD08s",
];

const client = new Client();

client.on("message", async (message) => {
  if (message.content === "!start") {
    const voiceChannel = message.member!.voice.channel!;
    while (true) {
      await procedure(voiceChannel);
    }
  }
});

const procedure = async (voiceChannel: VoiceChannel) => {
  console.log("New procedure.");
  
  // Set up stream/dispatcher and play at a random time.
  let voiceConnection = await voiceChannel.join();
  let stream = ytdl(YOUTUBE_LINKS[Math.round(Math.random())]);
  let dispatcher = voiceConnection.play(stream, {
    seek: Math.floor(Math.random() * 100),
  });

  // Let it play for 10 seconds.
  await new Promise((resolve) => {
    setTimeout(resolve, 10_000);
  });

  dispatcher.end();

  return;
};

(async () => {
  await client.login(TOKEN);
})();

Things I tried (all same issue):

• dispatcher.destroy() instead of dispatcher.end()
• stream.destroy() instead of dispatcher.end()
• both dispatcher.end() and stream.destroy()
• No seek in voiceConnection.play
• No seek in voiceConnection.play and filter: "audioonly" in ytdl
• Changing ytdl settings

let stream = ytdl(YOUTUBE_LINKS[Math.round(Math.random())], {
    highWaterMark: 1 << 25,
    filter: "audioonly"
  });

Also causes faster increase in memory usage, because of the high water mark probably.

let stream = ytdl(YOUTUBE_LINKS[Math.round(Math.random())], {
    highWaterMark: 1 << 25,
  });

Same as above.

let stream = ytdl(YOUTUBE_LINKS[Math.round(Math.random())], {
    filter: "audioonly"
  });

I don’t use this option because streaming with “audioonly” gives a long delay when starting the audio, probably due to seeking to a timestamp. This does not happen when streaming both video and audio. However, they all have the same issue in the end.

Further details:

• discord.js version: ^12.2.0
• Node.js version: 13.9
• Operating system: Windows 10
• Priority this issue should have – please be realistic and elaborate if possible: not sure, depends on if this is a bug
• I have also tested the issue on latest master, commit hash:

Some related issues are #2951. I asked this question on the discord and another user had the same problem.