Java

Explain how the Circuit Breaker works and its states.

Tell me about task setting: Scrum, Agile, how was the development process conducted?

Have you implemented a full state machine or something else?

Did the duplicate requests come from some external service?

What is volatile in Java?

Uniqueness — is it something other than a key?

What is pessimistic and optimistic locking?

How to implement the request-reply pattern on Kafka?

What is backpressure?

Where was the idempotency-key stored?

What lock was used in practice for transaction processing?

Tell me about a project you worked on for a long time. What was your role and the team composition?

What backpressure strategies exist when the queue overflows?

What did you do when the payment gateway was down?

Why is an idempotency-key needed if you already perform a check at the business logic level?

How was the request's uniqueness ensured with two sources?.

In which thread is the event loop created?

What is cache stampede and cache penetration? How to deal with them?

How does a Circuit Breaker help reduce failures when accessing an external service?

How did you deal with deadlock during pessimistic locking?