Intent to Ship: Long Animation Frame Timing

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https://w3c.github.io/longtasks/

Summary

This is an extension of long tasks. It measures the task together with its subsequent rendering update, adding information such as long running scripts, rendering time, and time spent in forced layout and style ("layout thrashing"). Developers can use this as a diagnostic for "sluggishness", which is measured by INP, by finding the causes for main-thread congestion which is often the cause for bad INP.

Blink component

https://github.com/w3c/longtasks/blob/main/loaf-explainer.md

Risks

Interoperability and Compatibility

Gecko: Positive Not yet a formal signal but showed positive interest at WG call.

WebKit: No signal

Web developers: Positive (https://twitter.com/jebbacca/status/1653355406368952321) Wix, Taboola, and others have already experimented with this in Canary. Strong excitement from several partners at We Love Speed conference.

Other signals:

Ergonomics

It should work well with other performance timeline entries, mainly event-timing/INP.

Security

This feature exposes rendering time to iframes, which might be cross-origin (same-process). This is already observable today, by using requestAnimationFrame. Underwent internal security review. Note that everything in this feature is same-process.

WebView application risks

Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?

N/A

Debuggability

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?

Yes

Is this feature fully tested by https://wpt.fyi/results/long-animation-frame/tentative?label=experimental&label=master&aligned

Flag name on chrome://flags

LongAnimationFrameTiming

Finch feature name

None

Non-finch justification

None

Requires code in /chrome?

False

Tracking bug

https://groups.google.com/a/chromium.org/g/blink-dev/c/MClbXXUhOTs

This intent message was generated by Chrome Platform Status.

https://w3c.github.io/longtasks/#sec-PerformanceLongTaskTiming

Regarding the spec, I see that it's monkeypatching WebIDL, DOM and HTML. This feels odd in a WG-adopted spec.

Have you tried to PR these changes upstream?

Summary
This is an extension of long tasks. It measures the task together with its subsequent rendering update, adding information such as long running scripts, rendering time, and time spent in forced layout and style ("layout thrashing"). Developers can use this as a diagnostic for "sluggishness", which is measured by INP, by finding the causes for main-thread congestion which is often the cause for bad INP.

Blink component
https://github.com/w3c/longtasks/blob/main/loaf-explainer.md

Risks

Interoperability and Compatibility

Gecko: Positive Not yet a formal signal but showed positive interest at WG call.

WebKit: No signal

Can you link to the position requests?

Can you tick the other review boxes on the entry?

Links to previous Intent discussions
Intent to prototype:

This intent message was generated by Chrome Platform Status.

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Specification
https://w3c.github.io/longtasks/#sec-loaf-timing

Regarding the spec, I see that it's monkeypatching WebIDL, DOM and HTML. This feels odd in a WG-adopted spec.
Have you tried to PR these changes upstream?

Summary
This is an extension of long tasks. It measures the task together with its subsequent rendering update, adding information such as long running scripts, rendering time, and time spent in forced layout and style ("layout thrashing"). Developers can use this as a diagnostic for "sluggishness", which is measured by INP, by finding the causes for main-thread congestion which is often the cause for bad INP.

Blink component
https://github.com/w3c/longtasks/blob/main/loaf-explainer.md

Risks

Interoperability and Compatibility

Gecko: Positive Not yet a formal signal but showed positive interest at WG call.
Noam Rosenthal
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Jan 15, 2024, 11:34:19 PM1/15/24
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to Yoav Weiss, blink-dev

Regarding the spec, I see that it's monkeypatching WebIDL, DOM and HTML. This feels odd in a WG-adopted spec.
Have you tried to PR these changes upstream?

Was planning to upstream the monkey-patches once we have formal positive signals from Gecko/WebKit.

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