Builds are non-deterministic

[Rich-Harris]

Describe the bug

Running vite build twice can, in some circumstances, result in different chunking. Unfortunately the only repro I have uses SvelteKit (it comes from sveltejs/kit#8291) — I haven't been able to simplify it further.

Reproduction

https://github.com/Rich-Harris/vite-non-deterministic-build-repro

Steps to reproduce

git clone git@github.com:Rich-Harris/vite-non-deterministic-build-repro.git
cd vite-non-deterministic-build-repro
pnpm i
pnpm test
pnpm test
pnpm test
pnpm test

System Info

System:
    OS: macOS 12.6.3
    CPU: (10) arm64 Apple M1 Max
    Memory: 5.13 GB / 32.00 GB
    Shell: 5.8.1 - /bin/zsh
  Binaries:
    Node: 16.17.0 - ~/.nvm/versions/node/v16.17.0/bin/node
    Yarn: 1.22.19 - ~/.nvm/versions/node/v16.17.0/bin/yarn
    npm: 8.15.0 - ~/.nvm/versions/node/v16.17.0/bin/npm
  Browsers:
    Chrome: 109.0.5414.119
    Chrome Canary: 112.0.5574.0
    Firefox: 109.0.1
    Safari: 15.6.1
  npmPackages:
    vite: ^4.0.3 => 4.0.4

Used Package Manager

pnpm

Logs

No response

Validations

• Follow our Code of Conduct
• 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.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[sun0day]

The ./src/lib/ComponentA.svelte?svelte&type=style&lang.css and ./src/lib/ComponentB.svelte?svelte&type=style&lang.css virtual modules will generate the same css as below via @sveltejs/vite-plugin-svelte.

main.svelte-66r8fo{max-width:1024px;margin:0 auto;background:red}h1.svelte-66r8fo{font-size:2rem}

Is this as expected?

[Rich-Harris]

Yep, that's expected

[sun0day]

Two same css chunks will generate the same source code hash. Rollup has a Map to cache chunk hash.

The problem happens due to the css-post plugin's async renderChunk, can't guarantee the chunks emit order.

I see two options:

• css-post plugin add some extra no-side-effect code to the chunk to make chunks' hash diff
• ask Rollup to expose an API to detect whether a chunk source code hash exists

@bluwy @sapphi-red

[sapphi-red]

If I understand your comment correctly, this could happen without Vite.

I think it would be great if we can provide a reproduction (or a simplified repo that demonstrates the problem) and create a issue in rollup.

[sun0day]

If I understand your comment correctly, this could happen without Vite.

I think it would be great if we can provide a reproduction (or a simplified repo that demonstrates the problem) and create a issue in rollup.

A simplified repo is here: https://stackblitz.com/edit/vitejs-vite-acbane?file=src%2Fdom2%2Findex.ts,src%2Fdom1%2Findex.ts,src%2Findex.ts,vite.config.ts,src%2Fdom1%2Fdom1.css,build.js,package.json,src%2Fdom2%2Fdom2.css,_gitignore&terminal=dev

repro step:

• clone it to your local
• npm run build serveral times, and you will see the the CSS asset name would be dom1.css or dom2.css randomly

[sapphi-red]

@sun0day Thanks! I created a issue to rollup to discuss whether this can be fixed in rollup.
rollup/rollup#4909

[sapphi-red]

Reopening as the PR was partially reverted in rollup.

My thoughts: rollup/rollup#4919 (comment)

[bluwy]

Fixed in #12558