In-memory cache isn't compatible with thread-loader

[malash]

Environment

• Linaria version: 2.2.0
• Bundler (+ version): Webpack 5.64.4
• Node.js version: 16.3.0
• OS: macOS 12.0.1

Description

The PR #879 introduced an in-memory cache to fix rebuild issue and accelerate bundle time. It's awesome, but when I try to integrate the latest version of Linaria in my project, I found some output CSS code is missing.

I deep dived and realize the in-memory cache may not be compatible with thread-loader. thread-loader use a thread poll to execute loaders in non-main threads, which can hugely speed up Webpack's building time in a large project. Since the threads in NodeJS cannot share the same closure context, the cssLookup map could be empty when running outputCssLoader.ts in a brand new thread.

I'm not sure is this a bug or a feature request? because not all Webpack projects use the thread-loader. But in our project, the build time would become non-acceptable if I disabled the thread-loader. So I can provide a posable solution if you agree to fix this issue:

Solution

Add a new options to return the right of choice to Linaria users.

• cacheType: 'memory' | 'filesystem' (default: 'memory'):

This option is inspired from Webpack's cache.type. If set to memory the loader works in the same way as 2.2.0, and if set to filesystem it works in the same way as 2.1.0.

• cacheDirectory: string (default: '.linaria-cache'):

Same as previous. Only works when cacheType: 'filesystem'

Reproducible Demo

https://github.com/malash/linaria-issue-881

You can enable/disable this line and run yarn webpack, the check the result of dist/styles.css.

[malash]

cc @Anber

[Anber]

Hmm…
thread-loader docs say, that loaders in threads have some limitations:

• Loaders cannot emit files.
• Loaders cannot use custom loader API (i. e. by plugins).
• Loaders cannot access the webpack options.

I'll try to implement a configurable cache, but it looks like we can face more problems with this plugin.

[malash]

Hi @Anber I cost some time to implement this feature in #884 for Linaria v2. Could you please take a look ?

If it's approved, I can create another PR to cherry pick it into Linaria v3.