Your question is LFU Cache with TTL. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
You are given a hypothetical failing system that monitors online activity of users of a website; outline short-term and long-term solutions to fix it.
Asked in the final panel system design stage. Reported follow-ups: memory management and heap dump analysis per VM.
Address immediate containment, diagnosis, observability, data processing, model-serving changes, and a durable redesign. Explain how you would distinguish infrastructure failure from model or data failure, and how you would validate each fix.
