ThreadTimer.java

// https://mvnrepository.com/artifact/com.databasesandlife/java-common/8.8.0
import com.databasesandlife.util.Timer;

import java.util.ArrayList;
import java.util.Random;

public class ThreadTimer {
    
    public void main(String[] args) throws Exception {
        for (int maxCores = 1; maxCores < 50; maxCores++) {
            try (var ignored = new Timer(maxCores + " threads")) {
                var threads = new ArrayList<Thread>();
                for (int core = 0; core < maxCores; core++) {
                    threads.add(new Thread(() -> {
                        var random = new Random();
                        for (int work = 0; work < 100_000_000; work++)
                            random.nextInt();
                    }));
                }
                for (var t : threads) t.start();
                for (var t : threads) t.join();
            }
        }
    }
}