Java Backend interview practice

JVM internals, concurrency, Spring ecosystem depth, and API design — the classic Java loop with verbal trade-off drilling.

Topics this interview probes

JVM & memory model Concurrency utilities Spring & transactional boundaries GC tuning API design Streaming & reactive

Walk me through what happens in the JVM when a request thread blocks on a database call.
Compare CompletableFuture chains with virtual threads for I/O-heavy services — when does each win?
How do transactional boundaries interact with async code in Spring, and what goes wrong?

The live interviewer generates fresh, role-tailored questions — and drills down when your answers are vague.