Java

Как устроены lifecycle bean и проксирование в Spring? Какие механизмы прокси используются?

What is MVCC and VACUUM, why do tables bloat?

What is a full scan?

How to reconcile database changes and event publication?

What difficult technical problems did you solve?

How to diagnose deadlock?

Why is SERIALIZABLE not always used?

What production problem did you personally solve?

How to avoid duplicates when processing Kafka messages?

What is Kafka topic, partition, broker and consumer group?

Have you supported production: give an example of an online incident and your actions.

When should you use ConcurrentHashMap instead of HashMap? What are race conditions and deadlocks?

What are BeanPostProcessor and BeanFactoryPostProcessor?

What is the difference between synchronized and ReentrantLock?

How is HashMap structured internally, what happens during collisions and resize?

The SQL query takes 20 seconds instead of 200 ms. Describe the step-by-step process of finding the cause: execution plan, indexes, statistics, locks.

What was your area of responsibility in the project?

Describe the lifecycle of a singleton bean in Spring.

The service processes 100,000 RPS and crashes due to memory. Describe the process of finding the cause and suggest an architectural solution.

How to optimize JOINs?