Bun has an open PR adding shared-memory threads to JavaScriptCore
Bun creator Jarred Sumner has proposed an experimental pull request to WebKit that introduces shared-memory threads to the JavaScriptCore engine. This implementation allows developers to spawn threads that share the same heap and objects, effectively bypassing the traditional limitations of Web Workers that require message passing and structured cloning.
Why it matters
This development could fundamentally change JavaScript concurrency by enabling true multi-threading with shared state, potentially eliminating the performance overhead and architectural complexity associated with current worker-based models.
oven-sh / WebKit Public forked from WebKit/WebKit Notifications You must be signed in to change notification settings Fork 44 Star 110 Code Pull requests 52 Actions Projects Security and quality 0 Insights Additional navigation options Code Pull requests Actions Projects Security and quality Insights Shared-memory threads for JavaScriptCore (experimental, not working yet) # 249 Open Jarred-Sumner wants to merge 151 commits into main oven-sh/WebKit:main from jarred/threads oven-sh/WebKit:jarred/threads Copy head branch name to clipboard Conversation Commits 151 ( 151 ) Checks Files changed Open Shared-memory threads for JavaScriptCore (experimental, not working yet) # 249 Jarred-Sumner wants to merge 151 commits into main oven-sh/WebKit:main from jarred/threads oven-sh/WebKit:jarred/threads Copy head branch name to clipboard Conversation Jarred-Sumner commented Jun 6, 2026 edited Loading Uh oh! There was an error while loading. Please reload this page .
The content is a technical report on an open-source software contribution; it presents the technical capabilities and limitations of the proposed feature without political or ideological framing.
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