Comprehensive Collection of Advanced Backend Interview Questions

The interview process often starts with simple questions and progressively probes deeper knowledge, as illustrated by a Redis interview example.

Database Section

MySQL Topics

What are the common MySQL storage engines?

What is the principle behind indexes?

What are the roles of the three MySQL logs (redoLog, undoLog, binLog)?

Why choose B+‑tree indexes?

When can indexes become ineffective?

How to view execution plans?

How to optimize SQL queries?

What is the principle of MySQL master‑slave replication?

What causes database deadlocks and how to quickly locate and resolve them?

Transaction Isolation Levels

What isolation levels exist for transactions?

What problems can each isolation level cause?

Which isolation level is the default for MySQL and Oracle?

How does MySQL handle phantom reads?

Middleware Section

Message Queue (MQ) Topics

Have you used a message queue? Which one?

How to ensure 100% message loss‑free delivery?

How to solve duplicate message consumption?

How to implement ordered messages?

How to address transaction issues introduced by messages?

Sharding (Database Partitioning) Topics

Have you used sharding?

How to query non‑sharding‑key dimensions (e.g., query by userName when userID is the sharding key)?

How to query multiple dimensions and fields that are not sharding keys?

How to synchronize data and ensure dual‑write consistency for multi‑dimensional queries?

How to migrate data when introducing sharding later?

Redis Topics

Have you used Redis? What data structures does it support?

What is Redis's threading model?

How does Redis guarantee data persistence?

What are the implementation principles of AOF and RDB?

How does Redis achieve high availability?

What are cache penetration, cache breakdown, and cache avalanche, and how to prevent them?

Distributed Lock Topics

Have you used distributed locks? Which implementations?

Experience with Redis‑based or Zookeeper‑based distributed locks?

How to set reasonable lock expiration times and handle lock timeouts? What is Redisson's watchdog mechanism?

How does Redis ensure lock reliability in a cluster?

What is the RedLock algorithm?

Concurrency Programming Section

Lock‑Related Topics

Explain the underlying implementation of synchronized.

Differences among synchronized, volatile, and CAS.

Differences between synchronized and Lock.

What is CAS and its principle?

Drawbacks of CAS and solutions to the ABA problem.

Principles and implementation of AQS.

Experience with ReentrantReadWriteLock and its principle.

Thread Pool Topics

What types of thread pools exist and how to create them?

Explain core parameters of a thread pool and its execution process.

What happens when the thread pool queue is full upon task submission?

How to optimize thread pool parameters in production?

Distributed Systems Section

Distributed Theory

Explain your understanding of the CAP theorem.

Which registration centers have you used and what consistency models (AP/CP) do they follow?

Explain your understanding of the BASE theory.

Distributed Transaction Topics

How to solve distributed transaction problems? Which solutions have you used?

Explain the 2PC and 3PC protocols.

Experience with SEATA and its implementation process.

How to achieve eventual consistency using MQ?

Practical Engineering Section

How to design APIs and ensure their security?

How to quickly locate CPU overload issues?

How to design and implement a rate‑limiting component?

How to make a system withstand high traffic during flash‑sale events?

The article concludes by inviting readers to comment on whether they can answer these questions and provides additional recommended reading links.