Java

[Name] asked: Have you used Kotlin in projects?

[Name] asked: Tell about ELK, Prometheus, and monitoring stacks — what are they, what have you used, what are you better at?

[name] asked: What is partitioning (PARTITION) in PostgreSQL?

[name] asked: How to fix OutOfMemoryError? Describe the process step by step.

[name] asked: What happens to the metrics after Prometheus collects them?

[name] asked: Why is the item not in the heap?

[Name] asked: How to design the number of partitions for a new application with a load of 3000 messages per minute?

[name] asked: How does MDC work under the hood?

[name] asked: In what case can a LinkageError occur?

[name] asked: Counter — is just the number of events, how to work with it correctly in Grafana?

[name] asked: Why Redis specifically, and not an in-memory cache inside the application?

[имя] спросил: Как снять heap dump с Java-процесса в Kubernetes? Опиши по шагам в bash-консоли.

public static void a(long item) { b(item); System.out.println(item); } public static void b(long item) { c(item); } public static void c(long item) { d(item); } public static void d(long item) { System.out.println(item); item = 20L; // here }

class Task { private static int counter = 0; public static void main(String[] args) throws Exception { var thread1 = new Thread(() -> increase()); var thread2 = new Thread(() -> increase()); thread1.start(); thread2.start(); thread1.join(); thread2.join(); System.out.println(counter); } private static void increase() { for (int i = 0; i < 5000; i++) { counter++; } } }

[Name] asked: There is a large table with events/logs in production, it needs to be cleared. How exactly would you clear it?

[name] asked: What types of metrics are available in Micrometer for Java applications?

[name] asked: What are the main entities in Kafka, how do they interact, and what are their purposes?

[name] asked: Why store classes in Metaspace if they are already in the jar file on disk?

[name] asked: Tell about the exception hierarchy in Java.

class StackTask { public static void main(String[] args) { a(15); } public static void a(long item) { b(item); } public static void b(long item) { c(item); } public static void c(long item) { d(item); } public static void d(long item) { System.out.println(item); } }