TestCalculate.java

package stackoverflow;
import java.util.Random;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ThreadLocalRandom;
import java.util.function.DoubleUnaryOperator;
import java.util.stream.DoubleStream;



public class TestCalculate {

    private Random rnd = ThreadLocalRandom.current();

    private DoubleStream randomPoints(long points, double a, double b) {
        return  rnd.doubles(points)
                .limit(points)
                        .map(d -> a + d * (b - a));
    }

    public static void main(String[] args) throws Exception {
        DoubleUnaryOperator du = x -> (x * Math.sqrt(23.35 * x * x) / Math.sqrt(34.54653324234324 * x) / Math.sqrt(213.3123)) * Math.sqrt(1992.34513213124 / x) / 88392.3 * x + 3.234324;


        for (int i=0 ; i < 2; i++){
            int j = i ;
            CountDownLatch latch = new CountDownLatch(3);
            
            new Thread(() -> {
                TestCalculate test = new TestCalculate();
                int x = 0;
                System.out.println("Thread "+j+" start");
                long start = System.currentTimeMillis();
                while (x++ < 6) {
                    double d = test.randomPoints(50_000_000l, 2, 10).map(du).sum();
                    double end = (System.currentTimeMillis() - start) / 1000.0;
                    System.out.println(String.format("Thread %d: time: %5.2f seconds, result: %f",
                    		j, end, d));
                    latch.countDown();
                    start = System.currentTimeMillis();
                }
                System.out.println("Thread "+j+" stop");
            }).start();

            latch.await();

        }
    }
}