Parcel: build freeze on 1.9.2

[coffeeowl]

🐛 bug report

build freeze (as reported in https://github.com/parcel-bundler/parcel/issues/1537) still happens, luckily not as often (at least on Heroku) as it was before and there are some errors being thrown

⏳  Building assign.js...
(node:31252) UnhandledPromiseRejectionWarning: Error: socket hang up
    at createHangUpError (_http_client.js:313:15)
    at Socket.socketOnEnd (_http_client.js:416:23)
    at Socket.emit (events.js:187:15)
    at endReadableNT (_stream_readable.js:1081:12)
    at process._tickCallback (internal/process/next_tick.js:63:19)
(node:31252) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 2)
(node:31252) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
(node:31218) UnhandledPromiseRejectionWarning: Error: socket hang up
    at createHangUpError (_http_client.js:313:15)
    at Socket.socketOnEnd (_http_client.js:416:23)
    at Socket.emit (events.js:187:15)
    at endReadableNT (_stream_readable.js:1081:12)
    at process._tickCallback (internal/process/next_tick.js:63:19)
(node:31218) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 2)
(node:31218) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
(node:31218) UnhandledPromiseRejectionWarning: Error: socket hang up
    at createHangUpError (_http_client.js:313:15)
    at Socket.socketOnEnd (_http_client.js:416:23)
    at Socket.emit (events.js:187:15)
    at endReadableNT (_stream_readable.js:1081:12)
    at process._tickCallback (internal/process/next_tick.js:63:19)
(node:31218) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 3)

nothing happens after that, build process still gets stuck as before.

🌍 Your Environment

| Software | Version(s) |
| ---------------- | ---------- |
| Parcel | 1.9.2
| Node | 10.1.0
| npm/Yarn | 6.1.0
| Operating System | Linux 4.16.13-1-ARCH

[DeMoorJasper]

This seems unrelated to any recent updates, this seems to be originating from the hmr websocket

[coffeeowl]

I see. still, I definitely observed a build freeze on Heroku (though it was 1.9.0) where of course we don't run parcel in watch mode.

[coffeeowl]

BTW, it seems when this HMR problem happens it leaves .cache in a bad state, just restarting watch process doesn't help - even though build succeeds, application doesn't load due to some random errors (looks like some garbage code were generated). So, cache has to be removed.

[DeMoorJasper]

Would be nice to detect corrupt cache files, not sure how to implement this though (without performance penalty)

_{Sent with GitHawk}

[sonaye]

I'm facing the same issue @1.9.2, had to add "prestart": "rm -rf .cache", as a temp. workaround.

[coffeeowl]

And I can confirm that build freeze issue is still present in 1.9.2, happened a couple of times today. Also, corrupted builds happen pretty often, I have to remove .cache on like every 3rd build.

[DeMoorJasper]

@coffeeowl Could you create a reproducible example?

[coffeeowl]

For freeze or cache issue? Freeze - I don't think so, as for the cache issue - I'll try.

[DeMoorJasper]

Doesn't matter we need to fix both anyways

[Hammster]

@DeMoorJasper Example Repo: https://github.com/Hammster/parcel-1.9.x-freeze

This is a reproduction of the bug, it happens when you've got a lot of vue components, maybe this is generally the case when many files get processed at once.

I can fix it in our project by changing maxConcurrentCallsPerWorker to a value between 1 and 3 in this line.

https://github.com/parcel-bundler/parcel/blob/cc6018ebcb6bb068246ef77c0aa2ee227e11c7b4/src/workerfarm/WorkerFarm.js#L13

I am not sure if this is diffrent bug though that OP has, but the result is the same.

[DeMoorJasper]

@Hammster Tbh in environments like heroku parcel probably only gets 1 thread, so it should probably not even start using a worker.
But the overload issue is a known issue, see #1587 and #1595

[DeMoorJasper]

Should be fixed in latest version as workerfarm has been fixed.

[Muini]

I personnaly still have the freezing issue...

Windows 10
Parcel v1.9.7 (tried different versions, no results)
Node v8.11.3
npm v6.0.0
yarn v1.7.0

I tried to set variable env PARCEL_MAX_CONCURRENT_CALLS and/or PARCEL_WORKERS to different values, no success. (with and without no cache, no hmr etc)
It's on a vue project, with node-sass too.

I can successfully start the dev (not the build) if I comment most of my includes, then it's building successfully, and I can put them back one by one until I got everything working.

I have a dual boot with a linux (based on ubuntu) and I have the exact same problem. The env is the same except for the node version. So I don't think it's an OS issue.

Should I create a new issue ?

[tmchng]

I also continued to have freeze issues and traced the problem to WorkerFarm.js.

There's an option called warmWorkers that is hard-coded to true inside WorkerFarm.js. My build no longer freezes after I set it to false. I have not had the time to investigate why.

I ended up adding the following line to package.json postinstall script so set warmWorkers to false every time I install parcel:
sed -i 's/warmWorkers: true/warmWorkers: false/' ./node_modules/parcel-bundler/src/workerfarm/WorkerFarm.js

Update: my issue seems similar to #1836 and can be reproduced by trying to bundle only html+sass files. So I've made a comment there.

[DeMoorJasper]

Please feel free to open up a new issue with your findings @tmchng

[BBlackwo]

I've got the same issue as @Muini. If I comment out the @imports on the file it's freezing on, build, then go back and uncomment the @imports and build again I can get it working.

Setting the env variable PARCEL_WORKERS=1 and setting warmWorkers: false fixes my issue temporarily but annoying still. On OSX had to add '' at the start, so:

sed -i '' 's/warmWorkers: true/warmWorkers: false/' ./node_modules/parcel-bundler/src/workerfarm/WorkerFarm.js

My build looks like this:

parcel build src/file1.scss src/file2.scss src/file3.scss src/file4.scss

On parcel v1.9.7.

It hangs on: Building file4.scss...

[DeMoorJasper]

It appears to be an issue with node-sass not being able to handle multiple async requests like mentioned here: #1847

You can try out the PR #1847 , it should resolve your issue.

Let's move discussion for sass freezing here: #1836