Node.js hangs at process.exit() under certain circumstance

[crvv]

• Version: v9.3.0
• Platform: Linux and macOS
• Subsystem: process, libuv

To reproduce, create the following two files, install node-sass and run node index.js.
I got 'exit' printed and the Node.js process hanging.

There is a similar but different issue, sass/node-sass#857, which contains some helpful information for debugging.

This issue was initially reported at webpack-contrib/sass-loader#523 and I wrote a workaround at webpack/webpack#6193.

entry.scss

@import "_partial";

index.js

const sass = require('node-sass')

sass.render({
    file: 'entry.scss',
    importer: () => {},
},
    () => console.log('done')
)

console.log('exit')
process.exit()

[apapirovski]

Can you reproduce whatever the issue is without using node-sass? Based on reading the links, it seems like this is an issue with node-sass and not Node.js core.

[crvv]

The document says

It is important to note that calling process.exit() will force the process to exit as quickly as possible even if there are still asynchronous operations pending that have not yet completed fully

https://nodejs.org/dist/latest-v9.x/docs/api/process.html#process_process_exit_code

So I think this is an issue with Node.js core.

I will try to reproduce it without node-sass.

[sokra]

As far as I know to problem could be the following:

• node-sass grabs a thread from the node.js thread pool
• Using @import calls importer from the sass thread. Thread blocks until callback is called.
• Callback is never called, thread is deadlocked
• node.js joins the thread pool on exit, but thread is deadlocked

[bnoordhuis]

^ That's almost certainly it.

I'm going to close this out because there's no reason to believe it's an issue with node.js itself.

[brunolm]

I have the same problem but while using Ionic.

There's probably some thread that is deadlocked and I have to idea how to kill that process.

If I type in the terminal:

node
> process.exit()

It hangs... or a simple

node -v

it also hangs