A Spring Boot service mostly calls other services and the database. Load is growing to tens of thousands of requests per second, and Tomcat runs out of threads. Which concurrency model would you choose: increase the pool, move to virtual threads, or go with a reactive stack, and why?
~10 min by voice
How to approach it
The interviewer wants to see whether you understand why the thread-per-request model runs out of resources under IO-heavy load, and whether you can weigh three options (a bigger pool, virtual threads, a reactive stack), taking into account their cost, the real bottlenecks (connection pools) and the team's specifics.
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.