🏃 why-is-node-still-running

This is a port of mafintosh' why-is-node-running module to TypeScript, with modernized syntax and no dependencies.

1const { whyIsNodeStillRunning } = require('why-is-node-still-running');
2const { createServer } = require('net');
3
4const server = createServer();
5server.listen(0);
6
7whyIsNodeStillRunning();
8// There are 2 handle(s) keeping the process running

Installation

1npm i -D why-is-node-still-running

Usage

Always import this module first so that the asynchronous hook can be setup. The hook will log to the console by default, but you can provide it with a custom logger that implements error().

Example of usage with Jest

Sometimes Jest complains that there are asynchronous operations still hanging after the tests have been completed. When the --detectOpenHandles flag gives no output, you can try using this module to help pinpoint the cause:

1import { whyIsNodeStillRunning } from 'why-is-node-still-running';
2
3afterAll(async () => {
4	// Do your actual cleanup here
5	// [...]
6
7	// Print the handles still opened
8	await new Promise(resolve => setTimeout(() => {
9		whyIsNodeStillRunning();
10		resolve();
11	}, 4000));
12});

Don't forget to run Jest with --useStderr to show console output.

Alternatively, you can use this module to print some information about the stack regularly while the tests are running (e.g. see this comment).

License

1Copyright (c) 2020-present, cheap glitch
2
3Permission to use, copy, modify, and/or distribute this software for any purpose
4with or without fee is hereby  granted, provided that the above copyright notice
5and this permission notice appear in all copies.
6
7THE SOFTWARE  IS PROVIDED "AS IS"  AND THE AUTHOR DISCLAIMS  ALL WARRANTIES WITH
8REGARD TO THIS SOFTWARE INCLUDING  ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
9FITNESS.  IN NO  EVENT  SHALL THE  AUTHOR  BE LIABLE  FOR  ANY SPECIAL,  DIRECT,
10INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
11OF USE, DATA OR  PROFITS, WHETHER IN AN ACTION OF  CONTRACT, NEGLIGENCE OR OTHER
12TORTIOUS ACTION, ARISING OUT OF OR IN  CONNECTION WITH THE USE OR PERFORMANCE OF
13THIS SOFTWARE.