Java Interview Preparation
Production and Performance Interview Questions
Application performance, connection pools, JVM diagnostics, thread pools, payloads, and production troubleshooting.
Production and Performance Interview Focus
Application performance, connection pools, JVM diagnostics, thread pools, payloads, and production troubleshooting.
Interview questions
1. How do you improve Spring Boot application performance? Advanced
Start with evidence from metrics, logs, traces, thread dumps, heap dumps, database plans, and connection-pool statistics. Fix the largest measured bottleneck, set safe limits and timeouts, test the change under realistic load, and document the result. Avoid guessing or increasing every pool size because that can move the bottleneck elsewhere.
2. How do you configure connection pooling? Intermediate
Start with evidence from metrics, logs, traces, thread dumps, heap dumps, database plans, and connection-pool statistics. Fix the largest measured bottleneck, set safe limits and timeouts, test the change under realistic load, and document the result. Avoid guessing or increasing every pool size because that can move the bottleneck elsewhere.
3. What is HikariCP? Beginner
Start with evidence from metrics, logs, traces, thread dumps, heap dumps, database plans, and connection-pool statistics. Fix the largest measured bottleneck, set safe limits and timeouts, test the change under realistic load, and document the result. Avoid guessing or increasing every pool size because that can move the bottleneck elsewhere.
4. How do you tune the embedded server thread pool? Advanced
An embedded server is a web server packaged inside the application. The application can start with a Java command instead of requiring a separately installed server and manually deployed WAR file.
5. How do you detect memory leaks? Advanced
Start with evidence from metrics, logs, traces, thread dumps, heap dumps, database plans, and connection-pool statistics. Fix the largest measured bottleneck, set safe limits and timeouts, test the change under realistic load, and document the result. Avoid guessing or increasing every pool size because that can move the bottleneck elsewhere.
6. How do you troubleshoot high CPU usage? Advanced
Start with evidence from metrics, logs, traces, thread dumps, heap dumps, database plans, and connection-pool statistics. Fix the largest measured bottleneck, set safe limits and timeouts, test the change under realistic load, and document the result. Avoid guessing or increasing every pool size because that can move the bottleneck elsewhere.
7. How do you troubleshoot high memory consumption? Advanced
Start with evidence from metrics, logs, traces, thread dumps, heap dumps, database plans, and connection-pool statistics. Fix the largest measured bottleneck, set safe limits and timeouts, test the change under realistic load, and document the result. Avoid guessing or increasing every pool size because that can move the bottleneck elsewhere.
8. How do you troubleshoot slow API responses? Advanced
Start with evidence from metrics, logs, traces, thread dumps, heap dumps, database plans, and connection-pool statistics. Fix the largest measured bottleneck, set safe limits and timeouts, test the change under realistic load, and document the result. Avoid guessing or increasing every pool size because that can move the bottleneck elsewhere.
9. How do you identify thread-pool exhaustion? Advanced
Start with evidence from metrics, logs, traces, thread dumps, heap dumps, database plans, and connection-pool statistics. Fix the largest measured bottleneck, set safe limits and timeouts, test the change under realistic load, and document the result. Avoid guessing or increasing every pool size because that can move the bottleneck elsewhere.
10. How do you generate and analyze thread dumps? Advanced
Start with evidence from metrics, logs, traces, thread dumps, heap dumps, database plans, and connection-pool statistics. Fix the largest measured bottleneck, set safe limits and timeouts, test the change under realistic load, and document the result. Avoid guessing or increasing every pool size because that can move the bottleneck elsewhere.
11. How do you generate and analyze heap dumps? Advanced
Start with evidence from metrics, logs, traces, thread dumps, heap dumps, database plans, and connection-pool statistics. Fix the largest measured bottleneck, set safe limits and timeouts, test the change under realistic load, and document the result. Avoid guessing or increasing every pool size because that can move the bottleneck elsewhere.
12. How do you configure graceful shutdown? Intermediate
Start with evidence from metrics, logs, traces, thread dumps, heap dumps, database plans, and connection-pool statistics. Fix the largest measured bottleneck, set safe limits and timeouts, test the change under realistic load, and document the result. Avoid guessing or increasing every pool size because that can move the bottleneck elsewhere.
13. How do you configure request timeouts? Intermediate
Start with evidence from metrics, logs, traces, thread dumps, heap dumps, database plans, and connection-pool statistics. Fix the largest measured bottleneck, set safe limits and timeouts, test the change under realistic load, and document the result. Avoid guessing or increasing every pool size because that can move the bottleneck elsewhere.
14. How do you handle large request and response payloads? Advanced
Start with evidence from metrics, logs, traces, thread dumps, heap dumps, database plans, and connection-pool statistics. Fix the largest measured bottleneck, set safe limits and timeouts, test the change under realistic load, and document the result. Avoid guessing or increasing every pool size because that can move the bottleneck elsewhere.
15. How do you improve application startup time? Advanced
Start with evidence from metrics, logs, traces, thread dumps, heap dumps, database plans, and connection-pool statistics. Fix the largest measured bottleneck, set safe limits and timeouts, test the change under realistic load, and document the result. Avoid guessing or increasing every pool size because that can move the bottleneck elsewhere.
16. How do you troubleshoot database connection exhaustion? Advanced
Start with evidence from metrics, logs, traces, thread dumps, heap dumps, database plans, and connection-pool statistics. Fix the largest measured bottleneck, set safe limits and timeouts, test the change under realistic load, and document the result. Avoid guessing or increasing every pool size because that can move the bottleneck elsewhere.
17. How do you troubleshoot production issues without restarting the application? Advanced
Start with evidence from metrics, logs, traces, thread dumps, heap dumps, database plans, and connection-pool statistics. Fix the largest measured bottleneck, set safe limits and timeouts, test the change under realistic load, and document the result. Avoid guessing or increasing every pool size because that can move the bottleneck elsewhere.
How to Prepare for Java Technical Interviews
Use this Java technical interview question bank to revise core concepts and practise explaining your decisions clearly. The questions cover Java fundamentals, object-oriented programming, collections, exceptions, multithreading, Spring Boot, Hibernate, databases, and other topics used in real software development interviews.
Start with the fundamentals, then move to scenario-based questions and advanced topics. Filter questions by difficulty to build confidence gradually. A strong answer should define the concept, explain why it matters, and include a practical example when appropriate.
Continue your preparation with the Java tutorials, or explore all interview preparation tracks for managerial and company-focused questions.