System designHardsd-g371

Subject Ml systemsLevel Senior–Staff~50 minCommon in ML systems · Reliability & on-call interviewsIndustries Technology, Software development

Question

Design an online (continual) learning system for a feed-ranking model that must incorporate fresh engagement signal within minutes — a video going viral, a breaking news event — rather than waiting for a daily batch retrain. The risk: continually updating a live model on streaming feedback can let a feedback loop, a data spike, or a bad batch corrupt the model in production. Walk through the streaming-update architecture, how you push updated weights to the serving fleet safely, and how you contain or roll back a bad update.

What a strong answer looks like

Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts — data model, bottlenecks, consistency, failure modes — and name the trade-offs you are making.

Learn the concepts

Narrate your design

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Run or narrate your approach, then ask the coach.