Restore and enhance error handling for hanging inputs in `"use cache"` #74652

unstubbable · 2025-01-08T17:27:30Z

Uncached and forever hanging promises are currently not supported as input for "use cache" functions. One prominent example of this is the use of searchParams in a page with "use cache". Until Next.js version 15.1.1, the usage of such inputs led to an error during build after a timeout of 50 seconds. This behaviour relied on a bug in decodeReply though, and was hence broken after React fixed the bug. A build will now fail early with Error: Connection closed..

With this PR, we are restoring the timeout error behaviour by switching to the new decodeReplyFromAsyncIterable API, which allows us to keep an open stream when decoding the cached function's arguments.

In addition, in dev mode, we are now also propagating the error to the dev overlay.

ijjk · 2025-01-08T17:31:58Z

Tests Passed

ijjk · 2025-01-08T17:44:30Z

Stats from current PR

Default Build (Increase detected ⚠️)

General Overall increase ⚠️

	vercel/next.js canary	vercel/next.js hl/use-cache-hanging-inputs-error-handling	Change
buildDuration	18.6s	15.7s	N/A
buildDurationCached	14.6s	12.5s	N/A
nodeModulesSize	418 MB	418 MB	⚠️ +35.6 kB
nextStartRea..uration (ms)	396ms	398ms	N/A

Client Bundles (main, webpack)

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webpack-HASH.js gzip	1.71 kB	1.71 kB	N/A
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Legacy Client Bundles (polyfills)

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polyfills-HASH.js gzip	39.4 kB	39.4 kB	✓
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Client Pages

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link.html gzip	538 B	537 B	N/A
withRouter.html gzip	519 B	520 B	N/A
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Edge SSR bundle Size

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edge-ssr.js gzip	129 kB	129 kB	N/A
page.js gzip	208 kB	208 kB	N/A
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Middleware size

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Next Runtimes

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274-experime...dev.js gzip	322 B	322 B	✓
274.runtime.dev.js gzip	314 B	314 B	✓
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pages.runtim..prod.js gzip	21.9 kB	21.9 kB	✓
server.runti..prod.js gzip	916 kB	916 kB	N/A
Overall change	820 kB	820 kB	✓

build cache Overall increase ⚠️

	vercel/next.js canary	vercel/next.js hl/use-cache-hanging-inputs-error-handling	Change
0.pack gzip	2.09 MB	2.1 MB	⚠️ +1.81 kB
index.pack gzip	75.2 kB	75 kB	N/A
Overall change	2.09 MB	2.1 MB	⚠️ +1.81 kB

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Commit: 2151b79

unstubbable · 2025-01-10T14:00:43Z

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packages/next/src/server/use-cache/use-cache-wrapper.ts

test/e2e/app-dir/use-cache-hanging-inputs/app/uncached-promise/page.tsx

test/e2e/app-dir/use-cache-hanging-inputs/use-cache-hanging-inputs.test.ts

gnoff · 2025-01-17T22:58:36Z

packages/next/src/server/use-cache/use-cache-wrapper.ts

@@ -261,22 +268,49 @@ async function collectResult(
 }

 async function generateCacheEntryImpl(
-  workStore: WorkStore,
  outerWorkUnitStore: WorkUnitStore | undefined,


Is this argument always a prerender store? for a nested cache is there a similar timeout we need to observe for the async iterable? would this be a cache store in that case or undefined?

Uncached and forever hanging promises are currently not supported as input for `"use cache"` functions. One prominent example of this is the use of `searchParams` in a page with `"use cache"`. Until Next.js version 15.1.1, the usage of such inputs led to an error during build after a timeout of 50 seconds. This behaviour relied on a bug in `decodeReply` though, and was hence broken after React fixed the bug. A build will now fail early with `Error: Connection closed.`. With this PR, we are restoring the timeout error behaviour by switching to the new `decodeReplyFromAsyncIterable` API, which allows us to keep an open stream when decoding the cached function's arguments. In addition, in dev mode, we are now also propagating the error to the dev overlay.

Based on #74652, this adds error handling for `"use cache"` closures that use closed-over hanging promises. It uses a similar technique to encode the hanging promises into the serialized bound arguments string. In addition, we need to notify the cache signal when decrypting the bound args, since this operation does not resolve in the current task. This is now the same behavior as for encrypting the bound args (see #73521).

ijjk added created-by: Next.js team PRs by the Next.js team. tests type: next labels Jan 8, 2025

unstubbable force-pushed the hl/use-cache-hanging-inputs-error-handling branch 6 times, most recently from bd2e57a to c61c618 Compare January 10, 2025 14:00

unstubbable mentioned this pull request Jan 10, 2025

Error handling for hanging promises in "use cache" closures #74750

Merged

unstubbable marked this pull request as ready for review January 10, 2025 15:54

unstubbable requested a review from gnoff January 10, 2025 17:47

wyattjoh reviewed Jan 14, 2025

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packages/next/src/server/use-cache/use-cache-wrapper.ts Outdated Show resolved Hide resolved

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unstubbable force-pushed the hl/use-cache-hanging-inputs-error-handling branch from c61c618 to 837b7de Compare January 14, 2025 18:07

unstubbable mentioned this pull request Jan 16, 2025

Fix source mapping of generated cache wrapper calls #74987

Merged

unstubbable force-pushed the hl/use-cache-hanging-inputs-error-handling branch from 837b7de to b980539 Compare January 17, 2025 08:17

gnoff reviewed Jan 17, 2025

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unstubbable force-pushed the hl/use-cache-hanging-inputs-error-handling branch from c8ed464 to caf7b77 Compare January 18, 2025 22:22

unstubbable added 9 commits January 21, 2025 12:10

Exclude non-deterministic chunk names from test expectation

5bbdb54

Fix typo and URL in test

038c032

Increase test timeout

5b6440e

Ensure timeout errors for nested components are logged in dev mode

b42b9d5

Avoid duplicate logged errors

b3e0a64

Use isUseCacheTimeoutError in onError

72863da

Extract expected error message in test

0f7ccb2

Remove stale comment

3fb917f

unstubbable added 4 commits January 21, 2025 12:10

Resolve hanging promise when prerendering is aborted

0c3c4c6

Use setTimeout in uncached promise test

54eae65

Expect no error when searchParams are unused

4f9f1dd

Add nested cache test case

2151b79

unstubbable force-pushed the hl/use-cache-hanging-inputs-error-handling branch from caf7b77 to 2151b79 Compare January 21, 2025 11:12

unstubbable mentioned this pull request Jan 21, 2025

Fix chunk load handling during prerendering #75132

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gnoff approved these changes Jan 22, 2025

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unstubbable merged commit 338eb99 into canary Jan 22, 2025
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unstubbable deleted the hl/use-cache-hanging-inputs-error-handling branch January 22, 2025 21:39

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Restore and enhance error handling for hanging inputs in `"use cache"` #74652

Restore and enhance error handling for hanging inputs in `"use cache"` #74652

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gnoff Jan 17, 2025

Restore and enhance error handling for hanging inputs in "use cache" #74652

Restore and enhance error handling for hanging inputs in "use cache" #74652

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Restore and enhance error handling for hanging inputs in `"use cache"` #74652

Restore and enhance error handling for hanging inputs in `"use cache"` #74652

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