LGTM1 On Tue, Mar 7, 2023 at 10:12 AM Yoshisato Yanagisawa <yyanagis...@google.com> wrote:
> > > 2023年3月7日(火) 17:19 Yoav Weiss <yoavwe...@chromium.org>: > >> >> >> On Tue, Mar 7, 2023 at 1:03 AM 'Yoshisato Yanagisawa' via blink-dev < >> blink-dev@chromium.org> wrote: >> >>> Contact emails >>> >>> yyanagis...@google.com >>> >>> Explainer >>> >>> >>> https://github.com/yoshisatoyanagisawa/service-worker-skip-no-op-fetch-handler >>> >>> Specification >>> >>> https://github.com/w3c/ServiceWorker/pull/1672 >>> >> Glad to see the PR in almost-landing condition! :) Please follow up with any extra effort required to actually land it. > >>> Summary >>> >>> The feature makes the navigation of pages with no-op service worker >>> fetch handlers fast by skipping them. >>> >>> Some sites have a no-op (no operation) fetch listener (e.g. onfetch = () >>> => {}). Since having the fetch listener was one of the requirements to be >>> a progressive web app (PWA), we assume they did that to make their site >>> recognized as PWA. However, it only brings overheads to start a service >>> worker and execute a no-op listener without bringing any feature benefits >>> like caching or offline capabilities because the code does nothing. To >>> make the navigation to such pages faster, we would like to omit the service >>> worker start and the listener dispatch from the navigation critical path if >>> a user agent identifies that all the service worker's fetch listeners are >>> no-ops. >>> >>> From version 112, Chromium starts to show console warnings if all the >>> service worker’s fetch listeners are no-ops, and encourages developers to >>> remove the useless fetch listeners. Hopefully sites stop using the useless >>> fetch listeners and we can deprecate the feature in the future. >>> >>> Blink component >>> >>> Blink>ServiceWorker >>> <https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3EServiceWorker> >>> >>> TAG review >>> >>> https://github.com/w3ctag/design-reviews/issues/815 >>> >>> TAG review status >>> >>> Issues addressed >>> >>> Risks >>> >>> Interoperability and Compatibility >>> >>> We believe the change has very small compatibility risk. >>> >>> Updating the no-op fetch handler in a service worker is ignored, which >>> was not allowed to ignore before. Upon our observation, this happens to a >>> negligible amount ( >>> https://chromestatus.com/metrics/feature/timeline/popularity/4453). >>> >> >> It seems like we don't yet have data from this. >> Can you explain this counter a bit more? Doesn't it also count cases >> where an operational fetch handler is updated after initialization? >> >> > > Sure. The counter has been added in > https://chromium-review.googlesource.com/c/chromium/src/+/4190509, and > cherry-picked in M111, which is now eary stable according to > https://chromereleases.googleblog.com/. There is the counter to watch > all event handler updates in service worker > https://chromium-review.googlesource.com/c/chromium/src/+/4259225, and we > can see some numbers. > https://chromestatus.com/metrics/feature/timeline/popularity/4469 > Therefore, it might be safe to say that the number of run-time fetch > handler updates is too small and not observable. > Oh, ok. So after over a week in Stable, we see 0.00015% for the loose upper bound. That's reassuring! :) > >> >> >>> >>> https://github.com/yoshisatoyanagisawa/service-worker-skip-no-op-fetch-handler/#approaches-to-deal-with-the-handler-updates-after-the-initialization >>> >>> Navigation Preload is ignored for the no-op fetch handler. The spec >>> requires the same resource fetched twice for no-op fetch handler due to >>> lack of respondWith, which could result in two different network requests >>> in rare situation, but this behavior only happens when they are >>> misconfigured (a page was set up to send a Navigation Preload request they >>> do not use). >>> >>> >>> https://github.com/yoshisatoyanagisawa/service-worker-skip-no-op-fetch-handler/#how-does-it-work-with-navigation-preload >>> >>> Gecko: No signal ( >>> https://github.com/mozilla/standards-positions/issues/744) >>> >>> WebKit: No signal ( >>> https://github.com/WebKit/standards-positions/issues/129) >>> >>> Web developers: No signals. When you search with the query "A2HS", you >>> will find many sites recommending you to add a no-op fetch handler (e.g. >>> addEventListener("fetch", ()=>{})). Thus, you can easily assume that >>> people who want to make their site to be added to the home screen would >>> just add the no-op fetch handler for that purpose. Therefore, having the >>> no-op fetch handler is common among sites (upon our investigation on >>> popular site fetch handler usage, 3-5% of them were affected). Such >>> sites will benefit from shipping this performance improvement, but we do >>> not have specific examples of sites supporting this Intent. (Probably, if >>> they were aware of the problem, they would just remove the empty fetch >>> handler.) >>> >>> Other signals: >>> >>> 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? >>> >>> There are no special risks for WebView-based applications. >>> >>> >>> Debuggability >>> >>> If a service worker is affected, its "Fetch handler type" field in >>> chrome://serviceworker-internals/ will be EMPTY_FETCH_HANDLER. From >>> version 112, there will be a console warning saying "Fetch event handler is >>> recognized as no-op. No-op fetch handler may bring overhead during >>> navigation. Consider removing the handler if possible." if the service >>> worker is affected. >>> >>> 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> >>> ? >>> >>> No. The specification proposal adds this as an optional behavior, so >>> testing it with web platform tests is not very useful. (Note that no >>> existing web platform tests needed to be updated to allow this behavior, >>> since the observable changes are only visible in edge cases.) >>> >>> Flag name >>> >>> #skip-service-worker-fetch-handler >>> >>> Requires code in //chrome? >>> >>> False >>> >>> Tracking bug >>> >>> https://bugs.chromium.org/p/chromium/issues/detail?id=1347319 >>> >>> Estimated milestones >>> >>> DevTrial on desktop >>> >>> 111 >>> >>> DevTrial on Android >>> >>> 111 >>> >>> >>> 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). >>> >>> https://github.com/w3c/ServiceWorker/pull/1672 is mostly finished, but >>> still undergoing final review by the spec mentor. >>> >>> Link to entry on the Chrome Platform Status >>> >>> https://chromestatus.com/feature/5136946693668864 >>> >>> This intent message was generated by Chrome Platform Status >>> <https://chromestatus.com/>, and modified by hand. >>> >>> >>> -- >>> 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/CAPNB-6VZntByJg-K_GNFb4xENkOEsmR8GewsKNJFyWbqnsWAHw%40mail.gmail.com >>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAPNB-6VZntByJg-K_GNFb4xENkOEsmR8GewsKNJFyWbqnsWAHw%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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