Turbopack: Revert default loader runtime backend to child processes by bgw · Pull Request #90675 · vercel/next.js

bgw · 2026-02-28T01:04:25Z

We're getting crashes in node: https://github.com/vercel/workflow/actions/runs/22500511618/job/65186125774#step:10:224

It looks like this should be fixed in newer versions of node:

So we may enable the worker threads feature by default if we detect a new enough version of node or bun.

bgw · 2026-02-28T01:04:43Z

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nextjs-bot · 2026-02-28T01:12:20Z

Tests Passed

codspeed-hq · 2026-02-28T01:25:07Z

Merging this PR will not alter performance

✅ 17 untouched benchmarks
⏩ 3 skipped benchmarks¹

_{Comparing bgw/turbopack-node-default-child-processes (961d2c8) with canary (c5b2cf1)}

3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

nextjs-bot · 2026-02-28T01:29:46Z

Stats from current PR

✅ No significant changes detected

📊 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)	455ms	455ms	✓	█▁▁▁▁
Cold (Ready in log)	440ms	439ms	✓	█▂▁▂▁
Cold (First Request)	1.298s	1.247s	✓	█▃▃▃▁
Warm (Listen)	457ms	457ms	✓	█▂▁▁▁
Warm (Ready in log)	444ms	443ms	✓	█▂▁▁▁
Warm (First Request)	348ms	350ms	✓	▇▂▁▁▁

📦 Dev Server (Webpack) (Legacy)

📦 Dev Server (Webpack)

Metric	Canary	PR	Change	Trend
Cold (Listen)	456ms	456ms	✓	▁▄▁▁▁
Cold (Ready in log)	438ms	438ms	✓	▂▃▂▂▁
Cold (First Request)	1.945s	1.931s	✓	▁▂▁▁▁
Warm (Listen)	456ms	456ms	✓	▁▁▁▁▁
Warm (Ready in log)	438ms	439ms	✓	▂▃▂▂▁
Warm (First Request)	1.940s	1.962s	✓	▂▂▁▁▁

⚡ Production Builds

Metric	Canary	PR	Change	Trend
Fresh Build	3.846s	3.891s	✓	▇▄▁▁▃
Cached Build	3.924s	3.882s	✓	▇▄▁▁▃

📦 Production Builds (Webpack) (Legacy)

📦 Production Builds (Webpack)

Metric	Canary	PR	Change	Trend
Fresh Build	14.083s	14.071s	✓	▁▂▁▁▁
Cached Build	14.221s	14.301s	✓	▁▁▁▁▁
node_modules Size	475 MB	475 MB	✓	▁▁▁▁▁

📦 Bundle Sizes

Bundle Sizes

⚡ Turbopack

Client

Main Bundles: **401 kB** → **401 kB** ✅ -23 B

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

Server

Middleware

	Canary	PR	Change
middleware-b..fest.js gzip	764 B	762 B	✓
Total	764 B	762 B	✅ -2 B

Build Details

Build Manifests

	Canary	PR	Change
_buildManifest.js gzip	449 B	450 B	✓
Total	449 B	450 B	⚠️ +1 B

📦 Webpack

Client

Main Bundles

	Canary	PR	Change
5528-HASH.js gzip	5.54 kB	N/A	-
6280-HASH.js gzip	58.4 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	59.1 kB	-
Total	232 kB	233 kB	⚠️ +701 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	254 kB	255 kB	✓
Total	379 kB	379 kB	⚠️ +303 B

Middleware

	Canary	PR	Change
middleware-b..fest.js gzip	616 B	614 B	✓
middleware-r..fest.js gzip	156 B	155 B	✓
middleware.js gzip	43.8 kB	43.9 kB	✓
edge-runtime..pack.js gzip	842 B	842 B	✓
Total	45.4 kB	45.5 kB	⚠️ +88 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	4.02 MB	4.03 MB	🔴 +4.69 kB (+0%)
index.pack gzip	103 kB	102 kB	✓
index.pack.old gzip	103 kB	103 kB	✓
Total	4.23 MB	4.23 MB	⚠️ +3.81 kB

🔄 Shared (bundler-independent)

Runtimes

	Canary	PR	Change
app-page-exp...dev.js gzip	320 kB	320 kB	✓
app-page-exp..prod.js gzip	170 kB	170 kB	✓
app-page-tur...dev.js gzip	320 kB	320 kB	✓
app-page-tur..prod.js gzip	170 kB	170 kB	✓
app-page-tur...dev.js gzip	316 kB	316 kB	✓
app-page-tur..prod.js gzip	168 kB	168 kB	✓
app-page.run...dev.js gzip	317 kB	317 kB	✓
app-page.run..prod.js gzip	168 kB	168 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	70.9 kB	70.9 kB	✓
app-route-tu..prod.js gzip	49.3 kB	49.3 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	32.9 kB	32.9 kB	✓
pages-turbo....dev.js gzip	52.6 kB	52.6 kB	✓
pages-turbo...prod.js gzip	38.5 kB	38.5 kB	✓
pages.runtim...dev.js gzip	52.6 kB	52.6 kB	✓
pages.runtim..prod.js gzip	38.5 kB	38.5 kB	✓
server.runti..prod.js gzip	61.9 kB	61.9 kB	✓
Total	2.82 MB	2.82 MB	⚠️ +3 B

📝 Changed Files (1 file)

Files with changes:

server.runtime.prod.js

View diffs

server.runtime.prod.js

Diff too large to display

📎 Tarball URL

next@https://vercel-packages.vercel.app/next/prs/90675/next

lukesandberg

wild nodejs bug

sokra

This need to change the default value on next.js side too. See config-shared.ts

Match the Rust-side default change from the previous commit.

sokra · 2026-02-28T07:39:22Z

Merge activity

Feb 28, 7:39 AM UTC: @sokra merged this pull request with Graphite.

nextjs-bot added created-by: Turbopack team PRs by the Turbopack team. Turbopack Related to Turbopack with Next.js. labels Feb 28, 2026

bgw mentioned this pull request Feb 28, 2026

Turbopack: Allow turbopack-node backend to be swapped at runtime using an experimental config option #90671

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bgw requested a review from a team February 28, 2026 01:06

bgw marked this pull request as ready for review February 28, 2026 01:07

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bgw force-pushed the bgw/turbopack-node-default-child-processes branch 2 times, most recently from e8c9180 to ce31a4b Compare February 28, 2026 03:01

sokra approved these changes Feb 28, 2026

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bgw changed the base branch from bgw/turbopack-node-backend-at-runtime to graphite-base/90675 February 28, 2026 06:48

bgw force-pushed the graphite-base/90675 branch from 7836721 to c5b2cf1 Compare February 28, 2026 06:48

bgw force-pushed the bgw/turbopack-node-default-child-processes branch from ce31a4b to bf0a740 Compare February 28, 2026 06:48

graphite-app bot changed the base branch from graphite-base/90675 to canary February 28, 2026 06:49

Turbopack: Revert default loader runtime backend to child processes

b03fc89

bgw force-pushed the bgw/turbopack-node-default-child-processes branch from bf0a740 to b03fc89 Compare February 28, 2026 06:49

Update default turbopackPluginRuntimeStrategy to childProcesses

961d2c8

Match the Rust-side default change from the previous commit.

nextjs-bot added the type: next label Feb 28, 2026

sokra approved these changes Feb 28, 2026

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sokra merged commit c2a2752 into canary Feb 28, 2026
290 of 292 checks passed

sokra deleted the bgw/turbopack-node-default-child-processes branch February 28, 2026 07:39

sokra restored the bgw/turbopack-node-default-child-processes branch February 28, 2026 07:46

xusd320 mentioned this pull request Mar 3, 2026

[Utoopack] unexpected crash on nodejs@22 utooland/utoo#2657

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Turbopack: Revert default loader runtime backend to child processes#90675

Turbopack: Revert default loader runtime backend to child processes#90675
sokra merged 2 commits intocanaryfrom
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