Common Interview Questions from Over 10 Companies – What You’ll Face

A friend recently secured a 16K position in a first‑tier city and compiled the interview questions he faced at more than ten companies. The list reflects the typical topics and difficulty level of technical interviews for backend roles.

Describe the JVM memory model.

How are JVM parameters configured in production?

Share your JVM tuning experience.

How to troubleshoot a slowdown in a production API?

What is the QPS of your project?

What to do when a downstream service call fails?

How do you set thread‑pool parameters?

Which design patterns are used in your project?

How to prevent duplicate repayment operations?

How are contract fields populated?

How to solve large old‑generation heap usage at the code level?

When can DDL statements cause table locks?

How do you handle cache data consistency issues?

Have you written custom annotations in a real project?

What should be considered for multi‑table joins?

How to resolve payment timeouts?

What are the core concerns of a flash‑sale system?

What scenarios cause transaction failures?

What implementations exist for optimistic locking?

Does SQL CRUD involve locks?

Does a SELECT statement involve locks?

How would you notice a query optimized from 2 s to 100 ms?

What is the purpose of a UID field in a Java class?

Is synchronized a re‑entrant lock and how is it released?

What is Redisson?

How to guarantee ordered message consumption?

How to handle message loss and detect failed message sends?

How to choose a thread‑pool blocking queue?

Describe a distributed‑transaction scenario you encountered and its solution.

How to resolve deadlocks?

How to ensure idempotency for loan applications when network timeouts cause multiple requests?

The author asks readers whether any of these questions seem particularly difficult and invites them to share which one they find hardest.