LGTM to experiment from 115 to 118 inclusive.
On 6/13/23 1:53 PM, Scott Haseley wrote:
Contact emails
shase...@chromium.org
Explainer
https://github.com/WICG/scheduling-apis/blob/main/explainers/yield-and-continuation.md
Specification
None
Summary
Provides a method for yielding control to the browser, which can be
used to break up long tasks. Awaiting the promise returned by
scheduler.yield() causes the current task to yield, continuing in a
new browser task. This can be used to improve responsiveness issues
caused by long tasks. Continuations are prioritized to mitigate
performance problems of existing alternatives.
Blink component
Blink>Scheduling>APIs
<https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3EScheduling%3EAPIs>
TAG review
https://github.com/w3ctag/design-reviews/issues/827
TAG review status
Pending
Risks
Interoperability and Compatibility
This is a new feature and will not change existing event loop task
scheduling, so the main risk is that other browsers might not
implement the feature. There is an interop challenge, however, that
comes with prioritization: we want to be specific enough to provide
developers guarantees and interoperable implementations, but provide
enough scheduling flexibility for UAs (like the HTML specification
does with task sources/task queues), which we'll keep in mind while
drafting the spec (see also
https://github.com/WICG/scheduling-apis/issues/67).
/Gecko/: No signal
/WebKit/: No signal
/Web developers/: No signals
/Other signals/:
Ergonomics
The default use (inserting yield points in long tasks) should enable
Chrome to maintain better performance (responsiveness). There is a
risk of continuations starving other work, but there are reasonable
mitigations, e.g. bounding total of prioritized continuations (see
also
https://github.com/WICG/scheduling-apis/blob/main/explainers/yield-and-continuation.md#preventing-task-starvation-by-continuations).
Activation
The feature would benefit from a polyfill so that tasks still yield in
the case the feature is unavailable. The behavior can be approximated
by awaiting `scheduler.postTask()` or wrapping `setTimeout(0)` in a
promise. The signal inheritance bit [1], however, would need
transpilation support to propagate the current signal across async
(Promise) boundaries. But developers can alternatively pass the
appropriate priority/signal if necessary on browsers that don't
support the feature.
Security
See
https://github.com/WICG/scheduling-apis/blob/main/explainers/yield-and-continuation.md#self-review-questionnaire-security-and-privacy
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?
None
Goals for experimentation
The main goal is to evaluate yielding with prioritized continuations
on site-specific metrics. More frequent yielding is known to improve
responsiveness (should also be measured in experiments), but there's
often a cost (latency) to regaining control of the thread. This API
prioritizes continuations to mitigate this, and we want to measure the
impact on site-specific metrics to evaluate the scheduling behavior.
Ongoing technical constraints
None.
Debuggability
This has basic new-API devtools support. We plan to work with the
devtools team to see if we can integrate continuations into the
performance panel in some way.
Will this feature be supported on all six Blink platforms
(Windows, Mac, Linux, Chrome OS, Android, and Android WebView)?
Yes
Is this feature fully tested by web-platform-tests
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?
Yes
DevTrial instructions
https://github.com/WICG/scheduling-apis/blob/main/implementation-status.md
Flag name
--enable-blink-features=SchedulerYield
Requires code in //chrome?
False
Tracking bug
https://bugs.chromium.org/p/chromium/issues/detail?id=979020
Estimated milestones
OriginTrial desktop last 118
OriginTrial desktop first 115
DevTrial on desktop 113
OriginTrial Android last 118
OriginTrial Android first 115
DevTrial on Android 113
OriginTrial webView last 118
OriginTrial webView first 115
Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/6266249336586240
Links to previous Intent discussions
Intent to prototype:
https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAKXGoJ1SBQP-ABM3%2BsDtKzUZiPoSCWqW2mLOjMrUfFBx4TomSw%40mail.gmail.com
This intent message was generated by Chrome Platform Status
<https://chromestatus.com/>.
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