Tell about the most complex/interesting task.

One of the most interesting tasks was related to optimizing a multithreaded Java application that processed large volumes of data in real-time.

The problem was that under high load, locks occurred and performance dropped. I conducted an analysis with a profiler, identified bottlenecks in synchronization, and redesigned part of the code using more efficient data structures from java.util.concurrent, minimizing critical sections.

An example of using ConcurrentHashMap for safe access from multiple threads:

import java.util.concurrent.ConcurrentHashMap;

public class Cache {
    private ConcurrentHashMap<String, String> map = new ConcurrentHashMap<>();

    public void put(String key, String value) {
        map.put(key, value);
    }

    public String get(String key) {
        return map.get(key);
    }
}

As a result, it was possible to significantly increase throughput and reduce system response time.