What problem arises in a production environment with multi-threaded access to a service (several REST requests in parallel)?

When accessing a service with multiple threads through parallel REST requests, a race condition may occur if the service uses shared mutable resources without proper synchronization.

For example, if several threads simultaneously modify a shared object or cache, data may become corrupted or lead to an inconsistent state.

To prevent this, you should:

• Use thread-safe data structures.
• Apply synchronization (synchronized, ReentrantLock, etc.).
• Avoid shared state or use immutable objects.
• Consider using local copies of data or atomic operations.

An example using synchronized in Java:

public class Counter {
    private int count = 0;

    public synchronized void increment() {
        count++;
    }

    public synchronized int getCount() {
        return count;
    }
}

Without such measures, errors and incorrect data may occur during parallel requests.