Atomics.waitAsync

Category: JavaScript
Type: New or changed feature
Status: Enabled by default (Chrome 87)
Intent stage: Shipped

Summary

Adds Atomics.waitAsync, the async version of Atomics.wait. Atomics.waitAsync allows programmers to wait on a SharedArrayBuffer location in the same fashion as Atomics.wait but returns a Promise instead.

Motivation

Atomics.wait blocks the thread and cannot be used on the main web browser thread, where blocking is disallowed. This makes coordination via SharedArrayBuffers between the main thread and worker threads more ergonomic.

Standards & signals

Specification: https://tc39.es/proposal-atomics-wait-async/
Firefox: Positive — Feature reached Stage 3 in TC39. Bug doesn't seem to have activity. Lars Hansen, who works at Mozilla, is a champion of this proposal. Request for position: https://github.com/mozilla/standards-positions/issues/433
Safari: Positive — Feature reached Stage 3 in TC39. Request for position: https://lists.webkit.org/pipermail/webkit-dev/2020-August/031367.html
Web developers: No signals
Tracking bug: https://bugs.chromium.org/p/v8/issues/detail?id=10239

Docs: https://docs.google.com/document/d/1dthXsVHMc1Sd_oYf9a-KZSFOd_a8dUgnt4REAG8YIXA/edit?usp=sharing https://docs.google.com/document/d/1aeEGDm1XSqoJkQQKz9F75WqnuAa2caktxGy_O_KpO9Y/edit?usp=sharing

Explainers: https://github.com/tc39/proposal-atomics-wait-async/blob/master/PROPOSAL.md

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