[Do not merge] Initial fix of #30549

[awareness481]

Bug

• fixes Unable to view localhost when "concurrentFeatures" is enabled. Requests are left to time out. #30549
• Integration tests added

Documentation / Examples

• Make sure the linting passes by running yarn lint

This issue actually occurs due to two separate bugs. First we have next/build/webpack/loaders/next-middleware-ssr-loader/index.ts

The bug occurs because the following code doesn't check whether _app & _document exists but just links to them,

  const stringifiedAbsoluteDocumentPath = getStringifiedAbsolutePath(
    this,
    './pages/_document'
  )
  const stringifiedAbsoluteAppPath = getStringifiedAbsolutePath(
    this,
    './pages/_app'
  )

I've currently added code to just link to the pages in .next as an initial fix.

Doing this fixes the file not found errors but reveals another issue. Upon visiting a route you will get an Error: Circular structure in "getInitialProps" result of page "/rsc" error. The error is thrown from this page _document . However upon reading the actual error, I found out that the issue is that Buffer is not defined. I added a temporary fix for that as well, however I'm not sure what the actual fix is here.

I know that Buffer is provided by webpack in the client but that doesn't seem to work here?

      targetWeb &&
        new webpack.ProvidePlugin({
          Buffer: [require.resolve('buffer'), 'Buffer'],
          process: [require.resolve('process')],
        }),

I opened this PR because I believe I've provided useful information. Hopefully that's the case.

I used the rsc demo to help identify the issue (v12.0.2-canary.11) but note, I would advise to not use yarn next-with-deps as your local environment as it seems to be broken with react 18.

[awareness481]

The first part of the issue seems to be worked on on this #30642 but I still believe my explanation on the second part of the issue will be useful. Thanks

[ijjk]

Stats from current PR

Default Build (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	awareness481/next.js initial_fix	Change
buildDuration	23.6s	23.6s	⚠️ +90ms
buildDurationCached	4.9s	4.9s	-7ms
nodeModulesSize	294 MB	294 MB	⚠️ +1.9 kB

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	awareness481/next.js initial_fix	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.959	5.981	⚠️ +2.02
/ avg req/sec	631.51	417.98	⚠️ -213.53
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.949	1.997	⚠️ +0.05
/error-in-render avg req/sec	1282.72	1251.93	⚠️ -30.79

Client Bundles (main, webpack, commons)

	vercel/next.js canary	awareness481/next.js initial_fix	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	28 kB	28 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	71.9 kB	71.9 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	awareness481/next.js initial_fix	Change
polyfills-a4..dd70.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	awareness481/next.js initial_fix	Change
_app-HASH.js gzip	1.23 kB	1.23 kB	✓
_error-HASH.js gzip	194 B	194 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	327 B	327 B	✓
dynamic-HASH.js gzip	2.38 kB	2.38 kB	✓
head-HASH.js gzip	350 B	350 B	✓
hooks-HASH.js gzip	635 B	635 B	✓
image-HASH.js gzip	4.44 kB	4.44 kB	✓
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	1.87 kB	1.87 kB	✓
routerDirect..HASH.js gzip	321 B	321 B	✓
script-HASH.js gzip	383 B	383 B	✓
withRouter-HASH.js gzip	318 B	318 B	✓
334f979574ae..6f4.css gzip	106 B	106 B	✓
Overall change	13.1 kB	13.1 kB	✓

Client Build Manifests

	vercel/next.js canary	awareness481/next.js initial_fix	Change
_buildManifest.js gzip	459 B	459 B	✓
Overall change	459 B	459 B	✓

Rendered Page Sizes

	vercel/next.js canary	awareness481/next.js initial_fix	Change
index.html gzip	534 B	534 B	✓
link.html gzip	546 B	546 B	✓
withRouter.html gzip	528 B	528 B	✓
Overall change	1.61 kB	1.61 kB	✓

---

Default Build with SWC (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	awareness481/next.js initial_fix	Change
buildDuration	25s	25.3s	⚠️ +290ms
buildDurationCached	5.1s	4.9s	-164ms
nodeModulesSize	294 MB	294 MB	⚠️ +1.9 kB

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	awareness481/next.js initial_fix	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.848	6.213	⚠️ +2.37
/ avg req/sec	649.68	402.39	⚠️ -247.29
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	2.081	2.023	-0.06
/error-in-render avg req/sec	1201.39	1235.54	+34.15

Client Bundles (main, webpack, commons)

	vercel/next.js canary	awareness481/next.js initial_fix	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.3 kB	42.3 kB	✓
main-HASH.js gzip	28.2 kB	28.2 kB	✓
webpack-HASH.js gzip	1.43 kB	1.43 kB	✓
Overall change	72.1 kB	72.1 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	awareness481/next.js initial_fix	Change
polyfills-a4..dd70.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	awareness481/next.js initial_fix	Change
_app-HASH.js gzip	1.22 kB	1.22 kB	✓
_error-HASH.js gzip	180 B	180 B	✓
amp-HASH.js gzip	305 B	305 B	✓
css-HASH.js gzip	321 B	321 B	✓
dynamic-HASH.js gzip	2.38 kB	2.38 kB	✓
head-HASH.js gzip	342 B	342 B	✓
hooks-HASH.js gzip	622 B	622 B	✓
image-HASH.js gzip	4.46 kB	4.46 kB	✓
index-HASH.js gzip	256 B	256 B	✓
link-HASH.js gzip	1.91 kB	1.91 kB	✓
routerDirect..HASH.js gzip	314 B	314 B	✓
script-HASH.js gzip	375 B	375 B	✓
withRouter-HASH.js gzip	309 B	309 B	✓
334f979574ae..6f4.css gzip	106 B	106 B	✓
Overall change	13.1 kB	13.1 kB	✓

Client Build Manifests

	vercel/next.js canary	awareness481/next.js initial_fix	Change
_buildManifest.js gzip	460 B	460 B	✓
Overall change	460 B	460 B	✓

Rendered Page Sizes

	vercel/next.js canary	awareness481/next.js initial_fix	Change
index.html gzip	535 B	535 B	✓
link.html gzip	548 B	548 B	✓
withRouter.html gzip	529 B	529 B	✓
Overall change	1.61 kB	1.61 kB	✓

Commit: 7776754

[huozhi]

Thanks for the PR @awareness481

I added new checking that gIP is not allowed when you wanna play with server components and concurrent features #30642. But I didn't get chance to repro the buffer issue you mentioned above. Would you mind provide a minimal reproduction and steps in the issue?

[awareness481]

Thanks for the PR @awareness481

I added new checking that gIP is not allowed when you wanna play with server components and concurrent features #30642. But I didn't get chance to repro the buffer issue you mentioned above. Would you mind provide a minimal reproduction and steps in the issue?

Hey. The issue is only reproducible if you apply my fix, I can't seem to reproduce it after your fixes. So basically, doing

  // build/webpack/loaders/next-middleware-ssr-loader/index.ts
  const stringifiedAbsoluteDocumentPath = getStringifiedAbsolutePath(
    this,
    '/.next/server/pages/_document'
  )

  const stringifiedAbsoluteAppPath = getStringifiedAbsolutePath(
    this,
    '/.next/server/pages/_app'
  )

will get you a Error: Circular structure in "getInitialProps" result of page "/rsc" error and if you console.log the error you will get a Buffer is not defined error. I'm not sure if this error is something that can appear, given your implementation, going forward.

Thanks ❤️

Edit: Removing the following lines from this PR

// packages/next/pages/_document.tsx
        let bytes = 0
        if (typeof Buffer !== 'undefined') {
          bytes = Buffer.from(data).byteLength
        } else {
          bytes = new TextEncoder().encode(data).length
        }

should make the error appear. I used the rsc demo app,

Edit2: Let me know if my explanation doesn't make sense.