Contact emails
[email protected], [email protected]

Explainer
https://gist.github.com/domenic/c5bd38339f33b49120ae11b3b4af5b9b#file-1-explainer-md


Specification
None


Summary
This adds a new option, `extendedLifetime: true`, to the `SharedWorker` 
constructor. This requests that the shared worker be kept alive even after all 
current clients have unloaded. The primary use case is to allow pages to 
perform asynchronous work that requires JavaScript after a page unloads, 
without needing to rely on a service worker.


Blink component
Blink>Workers


Web Feature ID
shared-workers


TAG review
https://github.com/w3ctag/design-reviews/issues/1089


TAG review status
Pending


Origin Trial Name
Extended lifetime shared workers


Chromium Trial Name
SharedWorkerExtendedLifetime


Origin Trial documentation link
https://gist.github.com/domenic/c5bd38339f33b49120ae11b3b4af5b9b#file-1-explainer-md


WebFeature UseCounter name
kSharedWorkerExtendedLifetimeFeatureEnabled


Risks




Interoperability and Compatibility
We intend to specify that the lifetime timeout for these shared workers be 
extended in the same way as service workers. Because the exact timeout of 
service workers is left implementation-defined, it's possible that code using 
this new feature could be non-interoperable. However, this has so far not 
proved to be a major problem in practice for service workers.

Gecko: No signal (https://github.com/mozilla/standards-positions/issues/1227) 
Some unofficial tentative positive signals and engagement in the proposal issue.

WebKit: No signal (https://github.com/WebKit/standards-positions/issues/492) 
Some unofficial tentative negative signals in the proposal issue.

Web developers: Positive The problem of wanting to perform asynchronous work 
during unload is well-known, with the service worker workaround currently 
deployed, including by Google properties.

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?
None



Goals for experimentation



Reason this experiment is being extended
Developer participation in the Origin Trial has increased significantly, with 
most of the growth occurring since mid-September. As this momentum is recent, 
an extension is needed to allow developers sufficient time to conduct thorough 
experiments and to provide us with more comprehensive usage data and insights. 
To aid developers in their experimentation, we have also improved 
debuggability. The chrome://inspect/#workers page now indicates when a 
SharedWorker is using the extendedLifetime option. Separately, the 
standardization process is progressing well. The corresponding pull request to 
the WHATWG HTML specification (https://github.com/whatwg/html/pull/11600) is 
under review and has received positive signals, including an LGTM from Mozilla. 
Extending the trial will allow this real-world testing to continue while the 
specification solidifies.


Ongoing technical constraints
None


Debuggability
The chrome://inspect/#workers page indicates when a SharedWorker is using the 
extendedLifetime option.


Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, 
ChromeOS, Android, and Android WebView)?
NoShared workers are not yet supported on Android and Android WebView. However, 
we are concurrently working on enabling them there, and when we do, this 
feature will also be supported.


Is this feature fully tested by web-platform-tests?
Yeshttps://wpt.fyi/results/workers/tentative/SharedWorker-extendedLifetime.html


Flag name on about://flags
None


Finch feature name
SharedWorkerExtendedLifetime


Requires code in //chrome?
False


Tracking bug
https://issues.chromium.org/issues/400473072


Estimated milestones


Origin trial desktop first 139

Origin trial desktop last 142

Origin trial extension 1 end milestone 145




Anticipated spec changes

Open questions about a feature may be a source of future web compat or interop 
issues. Please list open issues (eg links to known github issues in the project 
for the feature specification) whose resolution may introduce web 
compat/interop risk (eg, changing to naming or structure of the API in a 
non-backward-compatible way).
We are currently discussing some details in preparation for specification. The 
exact nature of how the lifetime extension works with regard to non-window 
clients, particularly, has only recently reached a tentative conclusion.


Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5138641357373440?gate=5106410035740672


Links to previous Intent discussions
Intent to Experiment: 
https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6862683f.170a0220.16d1bf.0122.GAE%40google.com



This intent message was generated by Chrome Platform Status.

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