6.0.0-beta.3 regression, all chunks grew significantly in size

[sai-cb]

Describe the bug

Starting with Vite 6.0.0-beta.3, all chunks produced in the dist directory significantly grew in size.

vite v6.0.0-beta.2 building for production...
✓ 216 modules transformed.
dist/index.html                 0.38 kB │ gzip: 0.26 kB
dist/assets/index-BueeJHUf.js  19.84 kB │ gzip: 8.84 kB
✓ built in 779ms

vite v6.0.0-beta.3 building for production...
✓ 125 modules transformed.
dist/index.html                 0.38 kB │ gzip:  0.26 kB
dist/assets/index-XnBmJTxy.js  25.16 kB │ gzip: 10.13 kB
✓ built in 774ms

I've internally been able to confirm the increase is seen across a large number of modules and seems loosely proportional to the size of the source code (e.g. a 1370kb chunk is becoming a 1420kb chunk). The issue appears to be systematic, as if minification somehow became less efficient across the board.

Reproduction

https://stackblitz.com/edit/vitejs-vite-jeh9rn?file=main.js

Steps to reproduce

• Update Vite to either 6.0.0-beta.2 or 6.0.0-beta.3 in package.json
• Run npm install
• Run npm run build
• Witness the size of the chunks

System Info

System:
    OS: macOS 15.1
    CPU: (10) arm64 Apple M2 Pro
    Memory: 159.98 MB / 32.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.17.0 - ~/.nvm/versions/node/v20.17.0/bin/node
    Yarn: 4.1.0 - ~/.nvm/versions/node/v20.17.0/bin/yarn
    npm: 10.8.2 - ~/.nvm/versions/node/v20.17.0/bin/npm
    Watchman: 2024.08.26.00 - /opt/homebrew/bin/watchman
  Browsers:
    Chrome: 130.0.6723.91
    Firefox: 128.0
    Safari: 18.1
  npmPackages:
    vite: 6.0.0-beta.7 => 6.0.0-beta.3

Used Package Manager

npm

Logs

No response

Validations

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• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to vuejs/core instead.
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• The provided reproduction is a minimal reproducible example of the bug.

[sai-cb]

This seems to have been introduced in the @rollup/plugin-commonjs update above v27. This version of the plugin changes the default strictRequires parameter from "auto" to true:

rollup/plugins#1639

The following workaround allows to avoid the bundlesize increase:

export default defineConfig(() => {
  return {
    build: {
      commonjsOptions: {
        strictRequires: 'auto',
      },
    },
  };
});

However unclear what the ideal path forward would be here and why strictRequires is introducing that regression...

[bluwy]

I don't know if we're able to fix this other than plugin-commonjs trying to optimize the output a little. But from its docs, the larger output is expected as it's the safest option for deterministic builds that many have reported in #13672.

I think we should prefer the deterministic behaviour here to prevent unwanted issues down the road. If that's not an issue for you, you can set strictRequires: 'auto' manually. Or perhaps prefer ESM libraries more 😅

[sai-cb]

It may be worth to call out in the Release docs as this is a pretty tangible perf regression for production builds. A good number of consumers of Vite may be taken off guard by it.

[bluwy]

Yeah we can add some more notes on this at https://main.vite.dev/guide/migration.html#advanced

[sai-cb]

(To be clear feel free to keep open or close as you think is appropriate)

I am not familiar enough to give good quality advise. On the surface, both issues seem problematic, and it is unclear if any improvements can be made to strictRequires: true. But at least there is the option to pick your poison 😆 .

[bluwy]

I think we can leave this open to track the documentation changes needed, no worries 👍 Thanks for testing out the beta!