Rust in Production Prime Video with Alexandru Ene
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Oct 2, 2025 Join Alexandru Ene, Principal Engineer at Prime Video, as he delves into the fascinating transition of their UI from JavaScript to Rust. With a background in game development, Alexandru highlights how Rust's performance and safety elevate Prime Video's infrastructure. He discusses the challenges of ensuring a smooth user experience on various devices, the impact of WebAssembly, and the strategic approach of gradual migration. Plus, learn about the importance of onboarding engineers with an adaptable mindset and the unique intersections between UI and game engine design.
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GC Workarounds And New Panic Risks
- To limit GC jank, Prime Video disables garbage collection during animations and triggers GC at safe idle points.
- Moving to Rust removed that workaround but introduced panics that could crash the app if unchecked.
Migrate One Page At A Time
- Port functionality one page or feature at a time to avoid brittle cross-world interactions.
- Keep full-page boundaries while both JS and Rust coexist to simplify focus and state management.
Huge Input Latency Gains
- Replacing React + JS delivered massive input-latency improvements on worst devices.
- Simplifying layout logic plus Rust speed cut input latency from ~400ms to ~30ms.