Add trace span for module readFile

[timneutkens]

Makes most of the build-module timing visible.

Bug

• Related issues linked using fixes #number
• Integration tests added
• Errors have helpful link attached, see contributing.md

Feature

• Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
• Related issues linked using fixes #number
• Integration tests added
• Documentation added
• Telemetry added. In case of a feature if it's used or not.
• Errors have helpful link attached, see contributing.md

Documentation / Examples

• Make sure the linting passes

[ijjk]

Stats from current PR

Default Build

General Overall increase ⚠️

	vercel/next.js canary	timneutkens/next.js add/file-read-span	Change
buildDuration	12.7s	12.7s	-60ms
buildDurationCached	3s	2.9s	-100ms
nodeModulesSize	194 MB	194 MB	⚠️ +993 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	timneutkens/next.js add/file-read-span	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.811	2.81	0
/ avg req/sec	889.29	889.81	+0.52
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.34	1.34	✓
/error-in-render avg req/sec	1865.27	1865.27	✓

Client Bundles (main, webpack, commons)

	vercel/next.js canary	timneutkens/next.js add/file-read-span	Change
779.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	26.9 kB	26.9 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	70.8 kB	70.8 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	timneutkens/next.js add/file-read-span	Change
polyfills-a4..dd70.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	timneutkens/next.js add/file-read-span	Change
_app-HASH.js gzip	977 B	977 B	✓
_error-HASH.js gzip	194 B	194 B	✓
amp-HASH.js gzip	311 B	311 B	✓
css-HASH.js gzip	328 B	328 B	✓
dynamic-HASH.js gzip	2.67 kB	2.67 kB	✓
head-HASH.js gzip	351 B	351 B	✓
hooks-HASH.js gzip	918 B	918 B	✓
image-HASH.js gzip	4.12 kB	4.12 kB	✓
index-HASH.js gzip	260 B	260 B	✓
link-HASH.js gzip	1.66 kB	1.66 kB	✓
routerDirect..HASH.js gzip	320 B	320 B	✓
script-HASH.js gzip	386 B	386 B	✓
withRouter-HASH.js gzip	319 B	319 B	✓
bb14e60e810b..30f.css gzip	125 B	125 B	✓
Overall change	12.9 kB	12.9 kB	✓

Client Build Manifests

	vercel/next.js canary	timneutkens/next.js add/file-read-span	Change
_buildManifest.js gzip	494 B	494 B	✓
Overall change	494 B	494 B	✓

Rendered Page Sizes

	vercel/next.js canary	timneutkens/next.js add/file-read-span	Change
index.html gzip	539 B	539 B	✓
link.html gzip	551 B	551 B	✓
withRouter.html gzip	532 B	532 B	✓
Overall change	1.62 kB	1.62 kB	✓

---

Default Build with SWC (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	timneutkens/next.js add/file-read-span	Change
buildDuration	6.3s	6.5s	⚠️ +166ms
buildDurationCached	2.9s	3s	⚠️ +52ms
nodeModulesSize	194 MB	194 MB	⚠️ +993 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	timneutkens/next.js add/file-read-span	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.808	2.844	⚠️ +0.04
/ avg req/sec	890.19	879.05	⚠️ -11.14
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.317	1.359	⚠️ +0.04
/error-in-render avg req/sec	1898.23	1839.25	⚠️ -58.98

Client Bundles (main, webpack, commons)

	vercel/next.js canary	timneutkens/next.js add/file-read-span	Change
675-HASH.js gzip	13.8 kB	13.8 kB	✓
770.HASH.js gzip	178 B	178 B	✓
framework-HASH.js gzip	50.7 kB	50.7 kB	✓
main-HASH.js gzip	35 kB	35 kB	✓
webpack-HASH.js gzip	1.64 kB	1.64 kB	✓
Overall change	101 kB	101 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	timneutkens/next.js add/file-read-span	Change
polyfills-a4..dd70.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	timneutkens/next.js add/file-read-span	Change
_app-HASH.js gzip	1.33 kB	1.33 kB	✓
_error-HASH.js gzip	180 B	180 B	✓
amp-HASH.js gzip	315 B	315 B	✓
css-HASH.js gzip	331 B	331 B	✓
dynamic-HASH.js gzip	2.79 kB	2.79 kB	✓
head-HASH.js gzip	356 B	356 B	✓
hooks-HASH.js gzip	637 B	637 B	✓
image-HASH.js gzip	557 B	557 B	✓
index-HASH.js gzip	262 B	262 B	✓
link-HASH.js gzip	2.22 kB	2.22 kB	✓
routerDirect..HASH.js gzip	326 B	326 B	✓
script-HASH.js gzip	393 B	393 B	✓
withRouter-HASH.js gzip	322 B	322 B	✓
bb14e60e810b..30f.css gzip	125 B	125 B	✓
Overall change	10.1 kB	10.1 kB	✓

Client Build Manifests

	vercel/next.js canary	timneutkens/next.js add/file-read-span	Change
_buildManifest.js gzip	511 B	511 B	✓
Overall change	511 B	511 B	✓

Rendered Page Sizes

	vercel/next.js canary	timneutkens/next.js add/file-read-span	Change
index.html gzip	539 B	539 B	✓
link.html gzip	551 B	551 B	✓
withRouter.html gzip	533 B	533 B	✓
Overall change	1.62 kB	1.62 kB	✓

Commit: 8e9d93f