Document Rust worker task concurrency and capacity limits #371

Delivered

Delivered in PR #372, merge d855eff9ed4dc428b95b5149cc1f1e0b5bbd2633.

Final exact-head qualification, artifact deployment and actual Pages publication passed. After that publication, all eight canonical Rust-guide routes returned HTTP200 with the new worker-task-concurrency section, minimum4.3.1, both builder methods, independent lanes, shared clone capacity and async limits. All eight actual table-of-contents navigations and nine canonical/alternate entries per page passed. English, Japanese and Simplified Chinese390px light/dark views were inspected with legible CJK fonts and no document overflow.

Live sections: English, Ukrainian, Spanish, Portuguese, Chinese, Japanese, French, German.

The guide links the published SDK107 acceptance, explicitly requires Rust4.3.1 or newer, and warns that the separate installation tuple may select an older SDK. It does not promote a new tuple or rewrite #363's historical4.2.2 baseline. The earlier HTTP200 observation before Pages publication lacked the new section and was not treated as acceptance.

Original scope

Problem

The website Rust guide describes worker sessions, local activities and authoring, but does not tell readers how to configure workflow/activity task concurrency. Published SDK 4.3.1 delivers the bounded worker lanes accepted in SDK Rust #107. The guide is an explicit remaining consumer of that release.

Product review

This is guidance for a released capability, with no new SDK feature or protocol-floor request. The published artifact receipt verifies a normal Rust 1.86 registry installation with three configured slots, a fourth callback entering only after a slot is released, and seven completed workflows including a handled activity failure against published Server 2.11.0. Keep this scope separate from the historical 4.2.2 activity-payload compatibility baseline in website #363.

Acceptance

• The website Rust guide names max_concurrent_workflow_tasks and max_concurrent_activity_tasks, both defaulting to 10, and shows how to select serial execution with 1.
• Explain independent lanes in run/run_until, shared clone/run_once capacity, actual claimed-task heartbeat slots, separate query polling, and local activities consuming workflow slots.
• Explain that async callbacks must yield; concurrency settings do not isolate CPU work or make detached blocking work cancellable.
• Link the SDK API/installed acceptance and update all seven translations with identical code blocks and current source hashes.
• Pass documentation qualification and verify all eight public Rust guides after deployment. Send the website PR/deployment receipt to the SDK owner so SDK Keep Server Config tables clear of the sticky page navigation #107 can close its external-guide requirement.