Intent to Ship: Long Animation Frame Timing

[Noam Rosenthal]

Contact emails

nrose...@chromium.org

Explainer

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

Specification

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

Blink>PerformanceAPIs

TAG review

https://github.com/w3ctag/design-reviews/issues/911

TAG review status

Issues addressed

Chromium Trial Name

LongAnimationFrameTiming

Link to origin trial feedback summary

https://github.com/w3c/longtasks

Origin Trial documentation link

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 web-platform-tests?

Yes

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://bugs.chromium.org/p/chromium/issues/detail?id=1392685

Launch bug

https://launch.corp.google.com/launch/4244858

Adoption expectation

The origin trial was a big success, and opted into by both major companies (Wix, Microsoft, Google), smaller companies and several RUM providers.

Adoption plan

Shipping it in stable (with a minor API change that is underway) is already on track for wide adoption due to very positive response to origin trial.

Estimated milestones

Shipping on desktop	123
OriginTrial desktop last	123
OriginTrial desktop first	116

Shipping on Android	123
OriginTrial Android last	123
OriginTrial Android first	116

Shipping on WebView	123
OriginTrial webView last	123
OriginTrial webView first	116

Shipping on WebView

123

Anticipated spec changes

Open questions about a feature may be a source of future web compat or interop issues. Please list open issues (e.g. links to known github issues in the project for the feature specification) whose resolution may introduce web compat/interop risk (e.g., changing to naming or structure of the API in a non-backward-compatible way).

None. The issues raised in the TAG reviewed were previously addressed in the security review of this feature, and need some clarification but not spec changes.

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/6118675067699200

Links to previous Intent discussions

Intent to prototype: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAJn%3DMYbX%3DEOAwkEvDQY9Ja1trSXLFtM1XNsuw1Lr2QR88%2BTnqw%40mail.gmail.com Intent to Experiment: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAJn%3DMYbdL3atq6FvsfrR%3DVs%2Boexvt04zfjV97BNNPL76iPTGLg%40mail.gmail.com
Intent to Extend Experiment: https://groups.google.com/a/chromium.org/g/blink-dev/c/MClbXXUhOTs
Intent to Ship: https://groups.google.com/a/chromium.org/g/blink-dev/c/MClbXXUhOTs

This intent message was generated by Chrome Platform Status.

[Yoav Weiss]

Thanks for working on this important problem! :)

On Fri, Jan 12, 2024 at 11:31 AM Noam Rosenthal <nrose...@chromium.org> wrote:

Contact emails

nrose...@chromium.org

Explainer

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

Can the explainer be updated? e.g. I'm assuming that the "this is a work in progress... lots of things might change" disclaimer is no longer valid.

Beyond that, the script attribution parts are not really explained outside of examples. Is there some developer-facing documentation covering that elsewhere?

For example, it'd be good to cover how code is attributed for async calls, Promises that got resolved, etc.

Specification

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

The link above is broken. I think you meant 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

Blink>PerformanceAPIs

TAG review

https://github.com/w3ctag/design-reviews/issues/911

The discussion seems to still be ongoing..

 

TAG review status

Issues addressed

Chromium Trial Name

LongAnimationFrameTiming

Link to origin trial feedback summary

https://github.com/w3c/longtasks

Origin Trial documentation link

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: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAJn%3DMYbX%3DEOAwkEvDQY9Ja1trSXLFtM1XNsuw1Lr2QR88%2BTnqw%40mail.gmail.com Intent to Experiment: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAJn%3DMYbdL3atq6FvsfrR%3DVs%2Boexvt04zfjV97BNNPL76iPTGLg%40mail.gmail.com
Intent to Extend Experiment: https://groups.google.com/a/chromium.org/g/blink-dev/c/MClbXXUhOTs
Intent to Ship: https://groups.google.com/a/chromium.org/g/blink-dev/c/MClbXXUhOTs

This intent message was generated by Chrome Platform Status.

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[Noam Rosenthal]

On Sat, Jan 13, 2024 at 4:32 AM Yoav Weiss <yoav...@chromium.org> wrote:

Thanks for working on this important problem! :)

Thanks for reviewing, I realize that the chromestatus entry was erroneous/lacking in a few important bits, let me try to rectify this :)
Updating the chromestatus entry and posting the missing links in the reply. 

On Fri, Jan 12, 2024 at 11:31 AM Noam Rosenthal <nrose...@chromium.org> wrote:

Contact emails

nrose...@chromium.org

Explainer

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

Can the explainer be updated? e.g. I'm assuming that the "this is a work in progress... lots of things might change" disclaimer is no longer valid.

Done

https://github.com/w3c/longtasks/pull/130

 

Beyond that, the script attribution parts are not really explained outside of examples. Is there some developer-facing documentation covering that elsewhere?

For example, it'd be good to cover how code is attributed for async calls, Promises that got resolved, etc.

Yes: https://developer.chrome.com/docs/web-platform/long-animation-frames

There was no slot in chromestatus to add this but this one is much more comprehensive than the explainer.

 

Specification

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

The link above is broken. I think you meant https://w3c.github.io/longtasks/#sec-PerformanceLongTaskTiming

Specifically 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

Blink>PerformanceAPIs

TAG review

https://github.com/w3ctag/design-reviews/issues/911

The discussion seems to still be ongoing..

Fair, though the discussion rehashes problems that were discussed when we shipped long tasks and didn't introduce new concerns.

I have addressed all the concerns raised but it's up to the reviewer to respond to that. This was 1 month ago. We can also discuss them here or in another forum, or if we want to block until the TAG reviewer is satisfied with all the answers we can do that.

 

TAG review status

Issues addressed 

Chromium Trial Name

LongAnimationFrameTiming

Link to origin trial feedback summary

https://github.com/w3c/longtasks

Origin Trial documentation link

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.

https://github.com/mozilla/standards-positions/issues/929
(I also corrected the entry to say "No signal", the positive signals were only informal as I stated in the note)

 

WebKit: No signal

Can you link to the position requests?

https://github.com/WebKit/standards-positions/issues/283

 

 

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

Not sure I understand what boxes?

It's been 2 months since filing the official position and about a year since we discussed this in WebPerfWG, and we haven't received a formal signal from Gecko/WebKit, only informal (somewhat positive) sentiment. In the meantime the origin trial has been very successful, and the list of things missing in the implementation is pretty close to zero. Happy to proceed in whatever way the API owners see fit.

[Noam Rosenthal]

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. 

[Noam Rosenthal]

Updating that Mozilla gave an official positive signal:

https://github.com/mozilla/standards-positions/pull/962

Updated the corresponding chromestatus field.

[Manuel Rego Casasnovas]

On 15/01/2024 11:31, Noam Rosenthal wrote:
>
> Link to entry on the Chrome Platform Status
>
> https://chromestatus.com/feature/6118675067699200
> <https://chromestatus.com/feature/6118675067699200>
>
>
> Can you tick the other review boxes on the entry?
>
> Not sure I understand what boxes?

Yoav refers to the buttons to request other reviews (apart from the API
owners review that happens here).

In "Prepare to ship" section you can find buttons for the following reviews:
* Privacy
* Security
* Enterprise
* Debuggability
* Testing

You should click those to request a review from the different parties.

Cheers,
Rego

[Noam Rosenthal]

Gotcha thanks!
I totally missed those buttons... will file a UI bug on chromestatus, maybe their discoverability can be improved.

[Mike Taylor]

LGTM1

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[domenic via Chromestatus]

I found some interesting test failures at https://wpt.fyi/results/long-animation-frame/tentative/loaf-source-location-redirect.html?label=experimental&label=master&aligned . Do they represent anything worth worrying about, e.g. a potential breaking change? Assuming not, LGTM2.

[Noam Rosenthal]

Oh thanks for pointing it out! This wouldn't be a breaking change, probably a test bug from previous changes, will fix that before shipping of course.

On Wed, Jan 24, 2024 at 12:31 PM domenic via Chromestatus <admin+...@cr-status.appspotmail.com> wrote:

I found some interesting test failures at https://wpt.fyi/results/long-animation-frame/tentative/loaf-source-location-redirect.html?label=experimental&label=master&aligned . Do they represent anything worth worrying about, e.g. a potential breaking change? Assuming not, LGTM2.

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[Yoav Weiss (@Shopify)]

LGTM3

To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAJn%3DMYZU6mo7A42gsmBa97UUn3CJG_iuQR9HueVyUOmgdiXMqQ%40mail.gmail.com.