ERP Consultant

How to effectively use ConcurrentHashMap to gain advantages?

Can interfaces have methods with implementation or not?

What is the difference between non-repeatable read and phantom read?

What does a memory leak look like on a graph? How did you detect it?

Architectural task: there is a Users service and a Notification service. When registering a user, it is necessary to guarantee sending a message to Kafka (for sending email). How to ensure delivery guarantee if Kafka is unavailable?

Code review: find problems and suggest improvements in the controller code with the updateBalance method.

Tell me about indexes in databases — what are they for, what types are there?

How does partitioning work to solve the problem of table growth? Is the issue of bloating still relevant with this approach?

Tell about Graceful Shutdown — what it is used for and how you implemented it.

Tell me about Clean Architecture, Hexagonal Architecture, DDD — are you familiar with them, have you worked with them?

Live coding: Go tasks — concurrent requests, closures in goroutines, duplicate filtering, thread-safe counter, buffered channels, function timeout

What is PgBouncer and what problem does it solve in PostgreSQL?

What is the most basic interface for all collections?

What is P (processor) in the Go scheduler — is it a physical processor?

Have you ever used synchronization primitives in multithreading? Tell me about CountDownLatch, CyclicBarrier, Phaser, and others.

Have you been involved in development, architecture, or testing?

SOLID principles — tell me about each one.

What types of locks are there in a database? Which were used more often?

What is SELECT FOR UPDATE? What is it used for, have you worked with this construct?

What do you know about Barbara Liskov's principle (LSP)?