[Bug] Infinite loop on the webpack 5 example

[Kostas Bariotis]

• I'd be willing to submit the fix

Describe the bug

When running the webpack 5 example, there is an endless loop with webpack compiling the same files again and again.

To Reproduce

Just run the webpack 5 example.

Screenshots

Environment if relevant (please complete the following information):

• OS: OSX Big Sur
• Node version 14
• Mochapack version NA
• Webpack version 5

[Steven Petryk]

I found a gross workaround. You can compare webpack's filesystem with the incoming changes you want to write to your module, and bail out if they're the same:

const modulePath = "<YOUR MODULE'S *ABSOLUTE* PATH>"
const moduleContents = "<YOUR MODULE'S CONTENTS>"

let finalInputFileSystem = compiler.inputFileSystem;
while (finalInputFileSystem && finalInputFileSystem._inputFileSystem) {
  finalInputFileSystem = finalInputFileSystem._inputFileSystem;
}

const existing = finalInputFileSystem._virtualFiles[modulePath];
if (existing.contents != moduleContents) {
  virtualModules.writeModule(modulePath, moduleContents);
}

[Steven Petryk]

So maybe the fix here would just be that webpack-virtual-modules needs to ignore calls to writeModule when they wouldn't change the module.

[Victor Vlasenko]

@stevenpetryk This comparison should be done on caller side. wrtieModule is expected to match the behaviour of fs.writeFile, e.g. when you write the same contents the file timestamp should be updated and recompilation should be scheduled. It is a bug in the example

[Victor Vlasenko]

Closing as works as intended, we also have #89 which tells about the opposite intended behaviour. And only one behaviour from these two can exists, because they are in direct contradiction to each another.

[Ateş Göral]

@larixer

It is a bug in the example

I assume the said bug is still there? Running the webpack 5 example, I see an infinite compilation loop.

[Victor Vlasenko]

@atesgoral

It is a bug in the example

I assume the said bug is still there? Running the webpack 5 example, I see an infinite compilation loop.

Yes, it is still present in the example.

[Chad Johnson]

This still appears to be an issue. Seems to happen with @shopify/web-worker/webpack which uses webpack-virtual-modules. Happens when using webpack-dev-server (webpack serve) or webpack --watch.

[Bora Yuksel]

We are using this API on our end, and are seeing this infinite loop issue still. Opening a PR for a potential fix, but open to other suggestions. I don't think this and #89 need to be conflicting, we could hopefully have both issues fixed.