Contact emailsshase...@chromium.org Explainer https://github.com/WICG/scheduling-apis/blob/main/explainers/yield-and-continuation.md https://github.com/WICG/scheduling-apis/blob/main/explainers/prioritized-task-scheduling.md#scheduleryield
*Note*: The explainer includes parameters to yield(), but we're initially shipping this with only the default behavior described in the specification. It wasn't clear if the parameters were necessary, there was some concern internally over the exact behavior <https://github.com/WICG/scheduling-apis/issues/96>, and it complicates the API. They may yet prove necessary, but it's safer to roll this out --- handling the main use case --- and revisit later, if needed. Specificationhttps://wicg.github.io/scheduling-apis/#dom-scheduler-yield 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 componentBlink>Scheduling>APIs <https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3EScheduling%3EAPIs> TAG reviewhttps://github.com/w3ctag/design-reviews/issues/966 TAG review statusPending Chromium Trial NameSchedulerYield Link to origin trial feedback summary https://docs.google.com/document/d/1HSlhqWsamWyR9bwgtCzB2TpVW7CUm9QkyKbK0TdM0RA/edit?usp=sharing Origin Trial documentation link https://github.com/WICG/scheduling-apis/blob/main/implementation-status.md 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*: Positive ( https://github.com/mozilla/standards-positions/issues/1039) Note that the issue opened for yield() was folded in with the original Scheduling APIs proposal, as this is an enhancement to that. *WebKit*: No signal ( https://github.com/WebKit/standards-positions/issues/361) *Web developers*: Positive Several partners were able to improve site performance using the API during Origin Trial (see the Origin Trial feedback link for quotes). Also some tweets I found with positive sentiment: - https://x.com/cramforce/status/1588912606777335808 - https://x.com/mohamedmansour/status/1752909705842933943 - https://x.com/sebastienlorber/status/1589939130225475584 *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. [1] https://docs.google.com/document/d/1rIOBBbkLh3w79hBrJ2IrZWmo5tzkVFc0spJHPE8iP-E/edit#heading=h.c484rp62uh2i Security https://github.com/WICG/scheduling-apis/blob/main/explainers/yield-and-continuation.md#self-review-questionnaire-security-and-privacy https://wicg.github.io/scheduling-apis/#sec-security 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? No, this is a new API. 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, ChromeOS, 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 https://wpt.fyi/results/scheduler/tentative/yield?label=experimental&label=master&aligned DevTrial instructions https://github.com/WICG/scheduling-apis/blob/main/implementation-status.md Flag name on chrome://flags--enable-blink-features=SchedulerYield Finch feature nameNone Non-finch justificationNone Requires code in //chrome?False Tracking bughttps://bugs.chromium.org/p/chromium/issues/detail?id=979020 MeasurementUsage is measured by the SchedulerYield UseCounter: https://chromestatus.com/metrics/feature/popularity#SchedulerYield Availability expectationInitially available only in Chromium browsers. Adoption expectationFeature is a key part of optimizing long tasks, which contribute to poor responsiveness: https://web.dev/articles/optimize-long-tasks. Several partners are waiting for this API as part of INP optimization efforts. Adoption planThere has already communication with developers in anticipation of this API, e.g. https://web.dev/articles/optimize-long-tasks. I'll work with the devrel team on what additional communication may be required. Non-OSS dependencies Does the feature depend on any code or APIs outside the Chromium open source repository and its open-source dependencies to function? No. Estimated milestones Shipping on desktop 129 Origin trial desktop first 115 Origin trial desktop last 120 DevTrial on desktop 113 Shipping on Android 129 Origin trial Android first 115 Origin trial Android last 120 DevTrial on Android 113 Shipping on WebView 129 Origin trial WebView first 115 Origin trial WebView last 120 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). No breaking changes are expected, but enhancements may be added as we learn more from usage. We also may need to adjust our internal scheduling policies (i.e. relative ordering of task sources) depending on what we learn from early adopters. The open issue that could potentially affect this API is the naming of related "yieldy" APIs: https://github.com/WICG/scheduling-apis/issues/95. This was raised in the WebKit position, specifically that scheduler.render() (future API enhancement) doesn't quite fit. We plan to name around scheduler.yield(), and are leaning towards rolling scheduler.render() in as a yield() parameter -- but this is still TBD. Link to entry on the Chrome Platform Status https://chromestatus.com/feature/6266249336586240?gate=6275382550986752 Links to previous Intent discussionsIntent to Prototype: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAKXGoJ1SBQP-ABM3%2BsDtKzUZiPoSCWqW2mLOjMrUfFBx4TomSw%40mail.gmail.com Intent to Experiment: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAKXGoJ1Uj8nX5HrUT86iZ83YBj%3D6GJ4jnKZKYF3tOq%3D_twN_Yg%40mail.gmail.com This intent message was generated by Chrome Platform Status <https://chromestatus.com/>. -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to blink-dev+unsubscr...@chromium.org. To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAKXGoJ3q%2BzPuSwBQ6Xp48aCP6m1kdE30Znh4wuzB_bL16UQwBg%40mail.gmail.com.
