Sockets/file descriptors are left out open unless the body is consumed

Author: diegomansuaCreated Nov 15, 2022Updated Feb 16, 2026

Labelsbug

Sockets/file descriptors are left out open unless the body is consumed. This seems to happen in both Linux and MacOS.

Reproduction

I wrote a resourceExists util function to see if the given URL exists or not. Bear in mind that I'd normally use HEAD method for this but in some of the URLs I have to test that method is not implemented so I have to use a regular GET request.

Now given this code in an opensockettest.js file:

javascript

import fetch from 'node-fetch';

const urls = [
  'https://i.dailymail.co.uk/i/pix/2016/06/25/02/35A4954F00000578-0-image-a-13_1466819022937.jpg',
  'https://i.dailymail.co.uk/i/pix/2016/02/05/17/30EAB51200000578-0-image-m-5_1454695002729.jpg',
  'https://i.dailymail.co.uk/i/pix/2016/09/02/14/37D5E61C00000578-0-image-a-8_1472824415895.jpg',
  'https://i.dailymail.co.uk/i/pix/2017/10/24/19/45A4723600000578-0-image-a-2_1508868932466.jpg',
  'https://i.dailymail.co.uk/i/pix/2015/10/25/01/2DBFBEEA00000578-0-image-m-11_1445735767824.jpg',
  'https://i.dailymail.co.uk/i/newpix/2018/09/12/21/50189AEE00000578-0-image-a-16_1536785559682.jpg',
  'https://i.dailymail.co.uk/i/newpix/2018/06/14/11/4D38883100000578-0-image-a-1_1528971515562.jpg',
  'https://i.dailymail.co.uk/i/newpix/2018/09/10/15/4FFCB43B00000578-0-image-a-1_1536591220607.jpg',
  'https://i.dailymail.co.uk/i/newpix/2018/05/08/05/4BF69E0000000578-0-image-m-103_1525754036269.jpg',
  'https://i.dailymail.co.uk/1/2018/06/14/11/2018/06/14/10/video-3293220-219_636x358.jpg',
  'https://i.dailymail.co.uk/1s/2022/09/28/00/video-62865615-982_636x358.jpg',
  'https://i.dailymail.co.uk/1s/2022/10/05/16/63142239-0-image-a-7_1664982798552.jpg',
  'https://i.dailymail.co.uk/1s/2022/10/05/15/63140431-0-image-m-34_1664980059636.jpg',
  'https://i.dailymail.co.uk/1s/2022/10/05/12/63134711-0-image-m-25_1664969549665.jpg',
  'https://i.dailymail.co.uk/1s/2022/10/05/10/63131471-0-image-a-7_1664963489500.jpg',
  'https://i.dailymail.co.uk/1s/2022/09/30/17/video-62976713-405_636x358.jpg',
  'https://i.dailymail.co.uk/1s/2022/09/30/22/video-62986031-384_636x358.jpg',
  'https://i.dailymail.co.uk/1s/2022/10/01/07/62994677-0-image-m-4_1664607016900.jpg',
  'https://i.dailymail.co.uk/1s/2022/10/07/22/video-63243097-225_636x358.jpg',
  'https://i.dailymail.co.uk/1s/2022/09/25/14/62780539-0-image-a-19_1664113310966.jpg',
  'https://i.dailymail.co.uk/1s/2022/09/25/13/video-62779795-794_636x358.jpg',
  'https://i.dailymail.co.uk/1s/2022/11/11/21/64461065-0-image-m-4_1668203772838.jpg',
  'https://i.dailymail.co.uk/1s/2022/11/14/04/64515861-0-image-a-13_1668398628989.jpg',
  'https://i.dailymail.co.uk/1s/2022/10/25/21/video-63844227-187_636x358.jpg',
  'https://i.dailymail.co.uk/1s/2022/10/25/17/video-63836581-805_636x358.jpg'
];

const resourceExists = async (url) => {
  try {
    const response = await fetch(url);

    return response.ok;
  } catch (_) {
    return false;
  }
};

for (const url of urls) {
  await resourceExists(url);
}

console.log('Done');

// give some time to look for open file descriptors
await new Promise((resolve) => setTimeout(resolve, 60000));

Then I run it and look for open descriptors and I see a few after Done has been printed out.

bash

> node opensockettest.js
> ps aux | grep opensockettest
diego.manilla    49305   0.0  0.0 33740844    944 s017  S+   12:18pm   0:00.00 grep opensocket
diego.manilla    49284   0.0  0.1 46050880  47636 s015  S+   12:18pm   0:00.23 node opensockettest.js
> lsof -p 49284 | grep TCP | wc -l
5

Expected behavior

No file descriptors/socket should be left dangling even if the body is not used/consumed. At the moment to get around this I have to use an abort controller since the Response class doesn't have any sort of close or destroy method (edit: it seems that Node introduced ReadableStream.cancel() in v16.5 so maybe doing response.body.cancel() is an option, but I haven't tested it; edit2: it doesn't seem to work). This way no sockets seem to be left open.

javascript

const resourceExists = async (url) => {
  const controller = new AbortController();

  try {
    const response = await fetch(url, {signal: controller.signal});

    return response.ok;
  } catch (_) {
    return false;
  } finally {
    controller.abort();
  }
};

If this is expected behaviour maybe it could be mentioned in the docs, I couldn't find anything.

Screenshots

N/A

Your Environment

software	version
node-fetch	3.3.0
node	16.11.1
npm	8.0.0
Operating System	MacOS Monterey 12.6.1

Additional context

N/A.

Source: node-fetch/node-fetch

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