[Vite 3] Flaky Dev Server

[brillout]

Describe the bug

Vite 3 seems to introduce changes that make the dev server flaky.

Reproduction

https://github.com/vite-3-flaky-dev-server/vite-plugin-ssr

System Info

See reproduction's GitHub Actions.

Used Package Manager

pnpm

Logs

No response

Validations

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• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
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• The provided reproduction is a minimal reproducible example of the bug.

[patak-dev]

Thanks for creating the issue. Let us know once you find the problematic change in vite-plugin-ssr, as that may shed light in what is going to on Vite's side.
At least one of the CI issues was about optimized deps: https://github.com/vite-3-flaky-dev-server/vite-plugin-ssr/runs/7001960930?check_suite_focus=true
You could try to disable the scan free deps discovery using legacy.devDepsScanner: true. If CI is always green with that, it means that the new lazy discovery hides a race condition somewhere (that we could pin point once you find why vite-plugin-ssr was working before)

[brillout]

That's helpful. Thanks.

Btw I see this:

[10:55:27.989][stdout][/examples/preact-server-routing][npm run dev] 10:55:27 AM[vite]✨ new dependencies optimized: preact, preact/hooks
[10:55:27.989][stdout][/examples/preact-server-routing][npm run dev] 10:55:27 AM[vite]✨ optimized dependencies changed. reloading
[10:55:28.064][Browser Error][/examples/preact-server-routing][npm run dev] {
  "type": "error",
  "text": "Failed to load resource: the server responded with a status of 504 (Gateway Timeout)",
  "location": {
    "url": "http://localhost:3000/node_modules/.vite/deps/chunk-5CVR5ZPT.js?v=f1c20c3b",
    "lineNumber": 0,
    "columnNumber": 0
  },
  "args": []
}
[10:55:28.065][Browser Error][/examples/preact-server-routing][npm run dev] {
  "text": "Failed to fetch dynamically imported module: http://localhost:3000/pages/index/index.page.jsx",
  "location": ""
}

Seems like the Vite dev server fails to provide a module after optimizeDeps is updated. It's flaky as well (i.e. it's sometimes green).

[patak-dev]

A 504 here is normal after missing dependencies have been found. On-fly deps requests will respond with a 504 as these are outdated. The browser will reload the page and ask these again. Do you have code checking for these in the tests? It should ignore these 504 for deps.

[brillout]

I can't reproduce this with the Vite 3 beta anymore.

Not sure what happened here 😅 but I won't complain :-).

I guess we can close this.