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[compiler runtime] repro: infinite render with useMemoCache + render phase updates #30849

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merged 1 commit into from
Sep 5, 2024

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@mofeiZ mofeiZ commented Aug 29, 2024

Repro for an infinite render bug we found when testing internally. See equivalent codesandbox repro here.

When render phase updates cause a re-render, useMemoCache arrays for the fiber are cleared and recreated on every retry while hook state is preserved.

This pattern (queuing re-renders on the current fiber during render) is perfectly valid. I believe this is a bug as React compiler currently replaces useMemos with useMemoCache calls and inlined instructions, taking care to preserve existing memoization dependencies. This should be the identity transform, but runtime implementation differences mean that uncompiled code behaves as expected (no infinite render) while compiled code fails to render.

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vercel bot commented Aug 29, 2024

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name Status Preview Comments Updated (UTC)
react-compiler-playground ✅ Ready (Inspect) Visit Preview 💬 Add feedback Aug 29, 2024 9:18pm

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Comparing: 61739a8...c173745

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name +/- Base Current +/- gzip Base gzip Current gzip
oss-stable/react-dom/cjs/react-dom.production.js = 6.68 kB 6.68 kB +0.05% 1.83 kB 1.83 kB
oss-stable/react-dom/cjs/react-dom-client.production.js = 501.40 kB 501.40 kB = 89.99 kB 89.99 kB
oss-experimental/react-dom/cjs/react-dom.production.js = 6.69 kB 6.69 kB +0.05% 1.83 kB 1.83 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js = 508.52 kB 508.52 kB = 91.16 kB 91.16 kB
facebook-www/ReactDOM-prod.classic.js = 596.16 kB 596.16 kB = 105.70 kB 105.70 kB
facebook-www/ReactDOM-prod.modern.js = 572.44 kB 572.44 kB = 101.88 kB 101.88 kB

Significant size changes

Includes any change greater than 0.2%:

(No significant changes)

Generated by 🚫 dangerJS against 6a1722d

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thanks for the repro! let's land and we can work on a fix

@mofeiZ mofeiZ merged commit d72e477 into facebook:main Sep 5, 2024
184 checks passed
gnoff pushed a commit to vercel/next.js that referenced this pull request Sep 12, 2024

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This commit was created on GitHub.com and signed with GitHub’s verified signature.
**breaking change for canary users: Bumps peer dependency of React from
`19.0.0-rc-7771d3a7-20240827` to `19.0.0-rc-94e652d5-20240912`**

[diff
facebook/react@7771d3a7...94e652d5](facebook/react@7771d3a...94e652d)

<details>
<summary>React upstream changes</summary>

- facebook/react#30952
- facebook/react#30950
- facebook/react#30946
- facebook/react#30934
- facebook/react#30947
- facebook/react#30945
- facebook/react#30938
- facebook/react#30936
- facebook/react#30879
- facebook/react#30888
- facebook/react#30931
- facebook/react#30930
- facebook/react#30832
- facebook/react#30929
- facebook/react#30926
- facebook/react#30925
- facebook/react#30905
- facebook/react#30900
- facebook/react#30910
- facebook/react#30906
- facebook/react#30899
- facebook/react#30919
- facebook/react#30708
- facebook/react#30907
- facebook/react#30897
- facebook/react#30896
- facebook/react#30895
- facebook/react#30887
- facebook/react#30889
- facebook/react#30893
- facebook/react#30892
- facebook/react#30891
- facebook/react#30882
- facebook/react#30881
- facebook/react#30870
- facebook/react#30849
- facebook/react#30878
- facebook/react#30865
- facebook/react#30869
- facebook/react#30875
- facebook/react#30800
- facebook/react#30762
- facebook/react#30831
- facebook/react#30866
- facebook/react#30853
- facebook/react#30850
- facebook/react#30847
- facebook/react#30842
- facebook/react#30837
- facebook/react#30848
- facebook/react#30844
- facebook/react#30839
- facebook/react#30802
- facebook/react#30841
- facebook/react#30827
- facebook/react#30826
- facebook/react#30825
- facebook/react#30824
- facebook/react#30840
- facebook/react#30838
- facebook/react#30836
- facebook/react#30819
- facebook/react#30816
- facebook/react#30814
- facebook/react#30813
- facebook/react#30812
- facebook/react#30811

</details>

---------

Co-authored-by: vercel-release-bot <infra+release@vercel.com>
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4 participants