Spring Framework Case Studies & Practical Application 2

Question 1

A microservice needs to call three external APIs and aggregate results. Which Spring pattern best handles partial failures gracefully?

Accepted Answer

Use CompletableFuture with fallback methods via @CircuitBreaker

Answer

Combining CompletableFuture with circuit breaker patterns (e.g., Resilience4j) allows each downstream call to fail independently while still returning partial results.

Question 2

A Spring Boot app exposes a REST endpoint that must return data within 200ms. Profiling shows JPA queries are slow. What is the first optimization step?

Accepted Answer

Analyze generated SQL using spring.jpa.show-sql and add missing indexes

Answer

Identifying slow queries with show-sql and fixing missing indexes addresses the root cause before introducing caching complexity.

Question 3

You need to process 1 million CSV rows nightly without exhausting memory. Which Spring component is most appropriate?

Accepted Answer

Spring Batch with chunk-oriented processing

Answer

Spring Batch's chunk-oriented model reads, processes, and writes fixed-size chunks, keeping memory usage constant regardless of file size.

Question 4

A team reports that their Spring Security configuration allows unauthenticated users to access /admin/** in production but not locally. What is the most likely cause?

Accepted Answer

The dev profile has permitAll() on /admin/** and it is active in production

Answer

Profile-specific security configurations that use permitAll for convenience are a common cause of accidental production exposure.

Question 5

Your Spring Data JPA repository query returns stale data immediately after an update in the same transaction. What is the most likely reason?

Accepted Answer

The EntityManager first-level cache returns the in-memory version before flushing

Answer

The JPA persistence context (first-level cache) serves repeated reads from memory, so a derived finder query may return pre-update state until the context is cleared or the transaction ends.

Spring Framework Practice Test

Spring Framework Practice Test

Spring Framework Case Studies & Practical Application 2