Design a local in-memory cache for reference data in a Java service: it's read by thousands of requests per second, and the data in the source is updated every few minutes.
~10 min by voice
How to approach it
The interviewer wants to see whether you understand concurrent access in the JVM and can choose a structure and an update strategy for a "many reads, rare updates" profile: no locks on reads, no partially updated data, with memory under control and sensible behavior on failures.
The interviewer will ask this question and listen. Think out loud and ask for a hint if you need one. When you're done, pause or tap “That's my answer”. In about a minute, your score and the points you covered show up here.