Shared Array Buffers (SABs) on Android

Category: JavaScript
Type: New or changed feature
Status: Enabled by default (Chrome 88)
Intent stage: Prepare to ship

Breaking change: No
Enterprise impact: None
Spec maturity: Published standard
Web Platform Tests: No

WPT details: web-platform-tests/wpt#17719 web-platform-tests/wpt#17760 web-platform-tests/wpt#17761 web-platform-tests/wpt#17802 web-platform-tests/wpt#17909 web-platform-tests/wpt#18543 web-platform-tests/wpt#20116 web-platform-tests/wpt#22358

Summary

Adds the JavaScript type SharedArrayBuffer to Android gated behind COOP/COEP. The concept of a SharedArrayBuffer is that a message to a worker, is posted but instead of copying the content of the array just a reference to it is shared, so that all have the same view on the shared chunk of data in the memory. This feature is only targeting Android - https://www.chromestatus.com/feature/4570991992766464 handles all other platforms

Motivation

SABs are currently disabled in Chrome on Android. As COOP/COEP have been released we can use ‘self.crossOriginIsolated’ to re-enable SABs on Android in case the site is isolated

Standards & signals

Specification: https://tc39.github.io/ecma262/#sec-sharedarraybuffer-objects
Firefox: Shipped/Shipping — Shipped in 79
Safari: No signal
Web developers: Positive
Tracking bug: https://bugs.chromium.org/p/chromium/issues/detail?id=923807

Ecosystem

Web Platform Tests: https://wpt.fyi/results/?q=shared-array-buffers-sabs-on-android
Chrome Platform Showcase: https://chrome-platform-showcase.paulkinlan-ea.deno.net/features
GenDN reference: https://gendn.paulkinlan-ea.deno.net/features
chrome.dev demos search: https://www.google.com/search?q=site%3Achrome.dev+Shared%20Array%20Buffers%20(SABs)%20on%20Android
MDN Web Docs: https://developer.mozilla.org/en-US/search?q=Shared%20Array%20Buffers%20(SABs)%20on%20Android
Baseline status: https://webstatus.dev/?q=Shared%20Array%20Buffers%20(SABs)%20on%20Android

Docs: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer https://docs.google.com/document/d/1tXfF0sdMQJPtwc2qEGF_V_z5xiCkP3ayS5ByRz6Rc-A/edit?ts=5f236efa

Explainers: https://github.com/whatwg/html/issues/4732 https://github.com/whatwg/html/pull/4734

View on chromestatus.com