Embedded / IoT

When does an index degrade performance?

In a topic with 6 partitions, 6 more were added. The key is — userID. Will a message with the same key go to the same partition?

What is the purpose of the volatile keyword?

How does idempotency differ from Exactly-once delivery?

What is a memory leak in Java, considering there is a garbage collector?

How does JAR differ from WAR?

Was the integration adapter with payment gateways an abstraction over different providers?

What key storage strategies for idempotency exist besides Redis?

Have you faced deadlocks during parallel batch processing?

Consumer lag has increased to 10 million messages. What is the plan of action?

What is the 'synchronized' keyword?

Tell more about the development of microservices for billing and tariffing at MegaFon — how it all happened, what exactly did you do?

One of the three consumers has become unresponsive. What will happen to the partitions? What will happen if it becomes responsive again?