Conditionally load uncommon paths by timneutkens · Pull Request #90514 · vercel/next.js

timneutkens · 2026-02-25T12:55:22Z

What?

No changes in functionality. Just skips requiring modules that are not used in the common hot path of builds.

vercel · 2026-02-25T12:55:27Z

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Project	Deployment	Actions	Updated (UTC)
next-js	Error		Feb 25, 2026 1:11pm

timneutkens · 2026-02-25T12:55:37Z

Conditionally load uncommon paths #90514 👈 (View in Graphite)
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packages/next/src/build/swc/index.ts

nextjs-bot · 2026-02-25T13:18:50Z

Failing test suites

Commit: dc19106 | About building and testing Next.js

pnpm test packages/next/src/server/node-environment-extensions/fast-set-immediate.external.test.ts (job)

uncaught errors in setImmediate do not affect surrounding tasks or other immediates > unhandled rejections > Promise.resolve().then(...) (DD)
uncaught errors in setImmediate do not affect surrounding tasks or other immediates > unhandled rejections > throw in unawaited async IIFE (DD)
uncaught errors in setImmediate do not affect surrounding tasks or other immediates > unhandled rejections > Promise.reject(...) (DD)
uncaught errors in setImmediate do not affect surrounding tasks or other immediates > unhandled rejections > throw in async immediate (DD)

Expand output

● uncaught errors in setImmediate do not affect surrounding tasks or other immediates › unhandled rejections › Promise.resolve().then(...)

kaboom

  1089 |       } catch (err) {
  1090 |         done.reject(err)
> 1091 |       }
       |        ^
  1092 |     })
  1093 |
  1094 |     await done.promise

  at ../packages/next/src/server/node-environment-extensions/fast-set-immediate.external.test.ts:1091:31

● uncaught errors in setImmediate do not affect surrounding tasks or other immediates › unhandled rejections › Promise.resolve().then(...)

expect(received).toEqual(expected) // deep equality

Expected: {"error": [Error: kaboom], "kind": "unhandledRejection"}
Received: undefined

  1113 |     type Case = {
  1114 |       name: string
> 1115 |       immediate: (
       |                             ^
  1116 |         name: string,
  1117 |         error: Error,
  1118 |         log: (...args: any[]) => void

  at ../packages/next/src/server/node-environment-extensions/fast-set-immediate.external.test.ts:1115:40

● uncaught errors in setImmediate do not affect surrounding tasks or other immediates › unhandled rejections › throw in unawaited async IIFE

kaboom

  1089 |       } catch (err) {
  1090 |         done.reject(err)
> 1091 |       }
       |        ^
  1092 |     })
  1093 |
  1094 |     await done.promise

  at ../packages/next/src/server/node-environment-extensions/fast-set-immediate.external.test.ts:1091:31

● uncaught errors in setImmediate do not affect surrounding tasks or other immediates › unhandled rejections › throw in unawaited async IIFE

expect(received).toEqual(expected) // deep equality

Expected: {"error": [Error: kaboom], "kind": "unhandledRejection"}
Received: undefined

  1113 |     type Case = {
  1114 |       name: string
> 1115 |       immediate: (
       |                             ^
  1116 |         name: string,
  1117 |         error: Error,
  1118 |         log: (...args: any[]) => void

  at ../packages/next/src/server/node-environment-extensions/fast-set-immediate.external.test.ts:1115:40

● uncaught errors in setImmediate do not affect surrounding tasks or other immediates › unhandled rejections › Promise.reject(...)

kaboom

  1089 |       } catch (err) {
  1090 |         done.reject(err)
> 1091 |       }
       |        ^
  1092 |     })
  1093 |
  1094 |     await done.promise

  at ../packages/next/src/server/node-environment-extensions/fast-set-immediate.external.test.ts:1091:31

● uncaught errors in setImmediate do not affect surrounding tasks or other immediates › unhandled rejections › Promise.reject(...)

expect(received).toEqual(expected) // deep equality

Expected: {"error": [Error: kaboom], "kind": "unhandledRejection"}
Received: undefined

  1113 |     type Case = {
  1114 |       name: string
> 1115 |       immediate: (
       |                             ^
  1116 |         name: string,
  1117 |         error: Error,
  1118 |         log: (...args: any[]) => void

  at ../packages/next/src/server/node-environment-extensions/fast-set-immediate.external.test.ts:1115:40

● uncaught errors in setImmediate do not affect surrounding tasks or other immediates › unhandled rejections › throw in async immediate

kaboom

  1089 |       } catch (err) {
  1090 |         done.reject(err)
> 1091 |       }
       |        ^
  1092 |     })
  1093 |
  1094 |     await done.promise

  at ../packages/next/src/server/node-environment-extensions/fast-set-immediate.external.test.ts:1091:31

● uncaught errors in setImmediate do not affect surrounding tasks or other immediates › unhandled rejections › throw in async immediate

expect(received).toEqual(expected) // deep equality

Expected: {"error": [Error: kaboom], "kind": "unhandledRejection"}
Received: undefined

  1113 |     type Case = {
  1114 |       name: string
> 1115 |       immediate: (
       |                             ^
  1116 |         name: string,
  1117 |         error: Error,
  1118 |         log: (...args: any[]) => void

  at ../packages/next/src/server/node-environment-extensions/fast-set-immediate.external.test.ts:1115:40

nextjs-bot · 2026-02-25T13:38:25Z

Stats from current PR

🟢 1 improvement

Metric	Canary	PR	Change	Trend
node_modules Size	474 MB	474 MB	🟢 78.6 kB (0%)	█████

📊 All Metrics

📖 Metrics Glossary

Dev Server Metrics:

Listen = TCP port starts accepting connections
First Request = HTTP server returns successful response
Cold = Fresh build (no cache)
Warm = With cached build artifacts

Build Metrics:

Fresh = Clean build (no .next directory)
Cached = With existing .next directory

Change Thresholds:

Time: Changes < 50ms AND < 10%, OR < 2% are insignificant
Size: Changes < 1KB AND < 1% are insignificant
All other changes are flagged to catch regressions

⚡ Dev Server

Metric	Canary	PR	Change	Trend
Cold (Listen)	456ms	456ms	✓	▁▁▁▁▁
Cold (Ready in log)	440ms	441ms	✓	▁▁▂▂▁
Cold (First Request)	880ms	886ms	✓	▁▃▄▄▁
Warm (Listen)	455ms	456ms	✓	▁▁▁▁▁
Warm (Ready in log)	440ms	441ms	✓	▁▁▁▁▁
Warm (First Request)	346ms	348ms	✓	▂▁▁▂▂

📦 Dev Server (Webpack) (Legacy)

📦 Dev Server (Webpack)

Metric	Canary	PR	Change	Trend
Cold (Listen)	507ms	507ms	✓	▁▁▁▁▁
Cold (Ready in log)	485ms	485ms	✓	▁▁▁▁▁
Cold (First Request)	2.197s	2.238s	✓	▁▁▁▁▁
Warm (Listen)	508ms	508ms	✓	▁▁▁▁▁
Warm (Ready in log)	484ms	484ms	✓	▁▁▁▁▁
Warm (First Request)	2.253s	2.249s	✓	▁▁▁▁▁

⚡ Production Builds

Metric	Canary	PR	Change	Trend
Fresh Build	4.241s	4.156s	✓	▁▁▁▁▁
Cached Build	4.310s	4.182s	✓	▁▁▁▁▁

📦 Production Builds (Webpack) (Legacy)

📦 Production Builds (Webpack)

Metric	Canary	PR	Change	Trend
Fresh Build	16.167s	16.034s	✓	▁▁▄▁▃
Cached Build	16.199s	16.035s	✓	▁▁▃▁▃
node_modules Size	474 MB	474 MB	🟢 78.6 kB (0%)	█████

📦 Bundle Sizes

Bundle Sizes

⚡ Turbopack

Client

Main Bundles: **399 kB** → **399 kB** ✅ -8 B

80 files with content-based hashes (individual files not comparable between builds)

Server

Middleware

	Canary	PR	Change
middleware-b..fest.js gzip	766 B	761 B	✓
Total	766 B	761 B	✅ -5 B

Build Details

Build Manifests

	Canary	PR	Change
_buildManifest.js gzip	448 B	451 B	✓
Total	448 B	451 B	⚠️ +3 B

📦 Webpack

Client

Main Bundles

	Canary	PR	Change
5528-HASH.js gzip	5.54 kB	N/A	-
6280-HASH.js gzip	57.5 kB	N/A	-
6335.HASH.js gzip	169 B	N/A	-
912-HASH.js gzip	4.59 kB	N/A	-
e8aec2e4-HASH.js gzip	62.6 kB	N/A	-
framework-HASH.js gzip	59.7 kB	59.7 kB	✓
main-app-HASH.js gzip	256 B	254 B	✓
main-HASH.js gzip	39.1 kB	39.1 kB	✓
webpack-HASH.js gzip	1.68 kB	1.68 kB	✓
262-HASH.js gzip	N/A	4.59 kB	-
2889.HASH.js gzip	N/A	169 B	-
5602-HASH.js gzip	N/A	5.55 kB	-
6948ada0-HASH.js gzip	N/A	62.6 kB	-
9544-HASH.js gzip	N/A	58.3 kB	-
Total	231 kB	232 kB	⚠️ +754 B

Polyfills

	Canary	PR	Change
polyfills-HASH.js gzip	39.4 kB	39.4 kB	✓
Total	39.4 kB	39.4 kB	✓

Pages

	Canary	PR	Change
_app-HASH.js gzip	194 B	194 B	✓
_error-HASH.js gzip	183 B	180 B	🟢 3 B (-2%)
css-HASH.js gzip	331 B	330 B	✓
dynamic-HASH.js gzip	1.81 kB	1.81 kB	✓
edge-ssr-HASH.js gzip	256 B	256 B	✓
head-HASH.js gzip	351 B	352 B	✓
hooks-HASH.js gzip	384 B	383 B	✓
image-HASH.js gzip	580 B	581 B	✓
index-HASH.js gzip	260 B	260 B	✓
link-HASH.js gzip	2.5 kB	2.5 kB	✓
routerDirect..HASH.js gzip	320 B	319 B	✓
script-HASH.js gzip	386 B	386 B	✓
withRouter-HASH.js gzip	315 B	315 B	✓
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Total	7.97 kB	7.97 kB	✅ -2 B

Server

Edge SSR

	Canary	PR	Change
edge-ssr.js gzip	125 kB	125 kB	✓
page.js gzip	253 kB	254 kB	✓
Total	377 kB	378 kB	⚠️ +951 B

Middleware

	Canary	PR	Change
middleware-b..fest.js gzip	617 B	614 B	✓
middleware-r..fest.js gzip	156 B	155 B	✓
middleware.js gzip	43.9 kB	43.7 kB	✓
edge-runtime..pack.js gzip	842 B	842 B	✓
Total	45.5 kB	45.3 kB	✅ -194 B

Build Details

Build Manifests

	Canary	PR	Change
_buildManifest.js gzip	715 B	718 B	✓
Total	715 B	718 B	⚠️ +3 B

Build Cache

	Canary	PR	Change
0.pack gzip	3.99 MB	4 MB	🔴 +11.6 kB (+0%)
index.pack gzip	102 kB	102 kB	✓
index.pack.old gzip	102 kB	103 kB	🔴 +1.38 kB (+1%)
Total	4.19 MB	4.2 MB	⚠️ +13.2 kB

🔄 Shared (bundler-independent)

Runtimes

	Canary	PR	Change
app-page-exp...dev.js gzip	318 kB	318 kB	✓
app-page-exp..prod.js gzip	169 kB	169 kB	✓
app-page-tur...dev.js gzip	318 kB	318 kB	✓
app-page-tur..prod.js gzip	168 kB	168 kB	✓
app-page-tur...dev.js gzip	314 kB	314 kB	✓
app-page-tur..prod.js gzip	167 kB	167 kB	✓
app-page.run...dev.js gzip	315 kB	315 kB	✓
app-page.run..prod.js gzip	167 kB	167 kB	✓
app-route-ex...dev.js gzip	70.8 kB	70.8 kB	✓
app-route-ex..prod.js gzip	49.2 kB	49.2 kB	✓
app-route-tu...dev.js gzip	70.8 kB	70.8 kB	✓
app-route-tu..prod.js gzip	49.2 kB	49.2 kB	✓
app-route-tu...dev.js gzip	70.4 kB	70.4 kB	✓
app-route-tu..prod.js gzip	49 kB	49 kB	✓
app-route.ru...dev.js gzip	70.4 kB	70.4 kB	✓
app-route.ru..prod.js gzip	49 kB	49 kB	✓
dist_client_...dev.js gzip	324 B	324 B	✓
dist_client_...dev.js gzip	326 B	326 B	✓
dist_client_...dev.js gzip	318 B	318 B	✓
dist_client_...dev.js gzip	317 B	317 B	✓
pages-api-tu...dev.js gzip	43.2 kB	43.2 kB	✓
pages-api-tu..prod.js gzip	32.9 kB	32.9 kB	✓
pages-api.ru...dev.js gzip	43.2 kB	43.2 kB	✓
pages-api.ru..prod.js gzip	32.8 kB	32.8 kB	✓
pages-turbo....dev.js gzip	52.5 kB	52.5 kB	✓
pages-turbo...prod.js gzip	38.5 kB	38.5 kB	✓
pages.runtim...dev.js gzip	52.5 kB	52.5 kB	✓
pages.runtim..prod.js gzip	38.4 kB	38.4 kB	✓
server.runti..prod.js gzip	62 kB	62 kB	✓
Total	2.81 MB	2.81 MB	✅ -1 B

📎 Tarball URL

next@https://vercel-packages.vercel.app/next/prs/90514/next

mischnic · 2026-02-26T10:45:00Z

packages/next/src/shared/lib/turbopack/is-file-system-cache-enabled-for-build.ts

@@ -0,0 +1,7 @@
+import type { NextConfigComplete } from '../../../server/config-shared'
+
+export function isFileSystemCacheEnabledForBuild(


This file as a whole is a bit overkill and should be inlined into the 3 places that use it?

mischnic · 2026-02-26T10:45:38Z

packages/next/src/server/web/spec-extension/adapters/request-cookies.test.ts

 })

 describe('wrapWithMutableAccessCheck', () => {
+  let workUnitAsyncStorage: typeof import('../../../app-render/work-unit-async-storage.external').workUnitAsyncStorage


Do we really need to change it for the tests?

It was transitively including some polyfill in the tests that is no longer the case now.

nextjs-bot added created-by: Turbopack team PRs by the Turbopack team. type: next labels Feb 25, 2026

timneutkens marked this pull request as ready for review February 25, 2026 12:57

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timneutkens force-pushed the 02-25-conditionally_load_uncommon_paths branch from 7053048 to 05f5567 Compare February 25, 2026 13:08

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nextjs-bot added the tests label Feb 25, 2026

timneutkens added 3 commits February 25, 2026 18:42

Conditionally load uncommon paths

fe6ff00

Fix

424f9e8

Fix tests

dc19106

timneutkens force-pushed the 02-25-conditionally_load_uncommon_paths branch from eb5179c to dc19106 Compare February 25, 2026 17:42

mischnic reviewed Feb 26, 2026

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Conditionally load uncommon paths#90514

Conditionally load uncommon paths#90514
timneutkens wants to merge 3 commits intocanaryfrom
02-25-conditionally_load_uncommon_paths

timneutkens commented Feb 25, 2026 •

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		@@ -0,0 +1,7 @@
		import type { NextConfigComplete } from '../../../server/config-shared'

		export function isFileSystemCacheEnabledForBuild(

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