Intent to Extend Origin Trial: EventTiming

[Annie Sullivan]

Contact emails

n...@chromium.org, tdre...@chromium.org, sull...@chromium.org

Spec

Link to spec: https://wicg.github.io/event-timing/

Summary

Monitoring event latency today requires an event listener. This precludes measuring event latency early in page load, and adds unnecessary performance overhead. The Event Timing API gives developers insight into the latency of a subset of events triggered by user interaction. In order to capture user pain caused by slow initial interactions, the event timing API includes First Input Delay (FID).

Previous trial results are described at https://groups.google.com/a/chromium.org/forum/#!msg/blink-dev/mGkwLYpHOxM/T7pEAGVJCAAJ

Link to “Intent to Implement” blink-dev discussion

https://groups.google.com/a/chromium.org/forum/#!searchin/blink-dev/event$20timing%7Csort:date/blink-dev/QNE6TVQve-0/vITXx1N5BQAJ

Goals for experimentation

We’d like feedback from a new customer which expressed interest in the OriginTrial. Previous Intent to Experiment:
https://groups.google.com/a/chromium.org/forum/#!searchin/blink-dev/Intent$20to$20Extend$20Origin$20Trial$3A$20EventTiming%7Csort:date/blink-dev/sJ4lxamz2V0/9aGztXjfDgAJ

 

Experimental timeline

Current experiment began in M68 and is set to end at the end of M74. We’d like to extend the experiment until the end of M75.

Any risks when the experiment finishes?

No - this is a performance analytics API.

Reason this experiment is being extended

There are two main reasons:

• Allowing the new customer to try out the API, and potentially provide feedback.

• We were planning to ship on M74 but were unable to do so due to https://bugs.chromium.org/p/chromium/issues/detail?id=914500. We continue to actively work on this issue but it requires experimentation and did not launch in M74. We don’t want a long period of time during which this API is not available because it is exposed as an experimental metric in CrUX.

Ongoing technical constraints

None.

Debuggability

When enabled, FID is exposed via javascript either via PerformanceObserver (requires early registration) or via the performance timeline if it occurs before onload:

// Register observer during onload.

const performanceObserver = new PerformanceObserver …

performanceObserver.observe({entryTypes:['firstInput']});

// Or get it from the buffer.

performance.getEntriesByType(‘firstInput’);

Will this feature be supported on all five Blink platforms supported by Origin Trials (Windows, Mac, Linux, Chrome OS, and Android)?

Yes.

Link to entry on the feature dashboard

https://www.chromestatus.com/feature/5167290693713920

[Annie Sullivan]

ping?

[Daniel Bratell]

Unfortunately we ran out of time during the api owner meeting last night, and I try to stay out of Origin Trial decisions since so much of them depend on Google's internal systems, but I note that this is a further extension of something that has already been extended. The longer an origin trial runs, the higher risk that sites burn in an dependency on the feature and that it becomes impossible to do fixes before the final shipping.

If you can address that risk, that would make it easier (for someone else) to figure out how to proceed.

/Daniel

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[Annie Sullivan]

Thanks, Daniel!

We plan to ship FID in M76. We had wanted to ship in M75, but weren't able to resolve a bug fast enough to get experimental data back in time.

We don't think that burn in is a big concern because the origin trial is being used for data gathering only, and we'll be launching in one more milestone. We'd like to keep it available so that people consuming the data in the Chrome User Experience report can try out the API as well.

-Annie

[Chris Harrelson]

Based on that explanation, LGTM to extend to M75.

To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAJB_qsnqwaQQHh963s4%3DjBbWwKgY53VPBwXxEmzu1T3nwe1hSg%40mail.gmail.com.