Parcel hangs and uses 100% CPU

[lachenmayer]

🐛 bug report

Hi there, I'm trying to use Parcel to build a simple website. When I add the nanocomponent package to my dependencies and try to require it, parcel hangs and uses 100% CPU instead of building. When I remove this dependency, everything works fine. Please check out the repro here: https://github.com/lachenmayer/parcel-bundler-hang-repro

🎛 Configuration (.babelrc, package.json, cli command)

• No babelrc.

{
  "name": "parcel-bundler-hang-repro",
  "main": "index.js",
  "scripts": {
    "start": "parcel --no-cache index.html"
  },
  "dependencies": {
    "nanocomponent": "^6.5.2",
    "parcel-bundler": "^1.9.3"
  }
}

🤔 Expected Behavior

• Parcel bundles the project, serves it at localhost:1234
• When you open it in a browser, it prints "it works" and the contents of nanocomponent.

😯 Current Behavior

Parcel hangs:

$ yarn start
yarn run v1.6.0
(node:5033) [DEP0005] DeprecationWarning: Buffer() is deprecated due to security and usability issues. Please use the Buffer.alloc(), Buffer.allocUnsafe(), or Buffer.from() methods instead.
$ parcel --no-cache index.html
Server running at http://localhost:1234 
⏳  Building events.js...

💁 Possible Solution

I am aware of #1331 and #637 which seem similar.

I have tried downgrading Parcel to 1.7.1, but that did not help.

💻 Code Sample

https://github.com/lachenmayer/parcel-bundler-hang-repro

🌍 Your Environment

Software	Version(s)
Parcel	1.9.3
Node	10.5.0
Yarn	1.6.0
Operating System	macOS 10.12.6

Thanks a lot, Parcel is awesome!

[DeMoorJasper]

I've tried out the reproducable repo and I can confirm this bug, not sure what is causing it yet though.

[DeMoorJasper]

For some reason this line resolves to index.js, I'll dig deeper into why this is happening and try to find a fix

var onload = require('on-load'); // resolves to /index.js

[DeMoorJasper]

So I've found the bug and I'm not sure it should be fixed.

So the package on-load has an implicit relative path in it's browser field in pkg.json. We could check if it has an extension and treat those as files. Although this would give issues as some packages end with .js... So I suggest you open up an issue with the maintainer asking for a more explicit relative path as explained below.

This:

"browser": {
    "assert": "nanoassert",
    "./server.js": "index.js"
  }

Should be this:

"browser": {
    "assert": "nanoassert",
    "./server.js": "./index.js"
  }

We could also change Resolver.getAlias to handle this behaviour but like explained above, this could cause other issues for packages that end with a known extension in their name (for example something.js). So I think it's best to leave it up to the package maintainers to properly use explicit filenames in package.json

[DeMoorJasper]

I've opened up a PR in the pkg.

[lachenmayer]

Thanks so much for your speedy response and for opening the PR, much appreciated!