public class Test {

    public static void main(String[] args) throws ExecutionException, InterruptedException {


        ExecutorService executor = Executors.newFixedThreadPool(3);
        int result1 = executor.submit(() -> {
            System.out.println("1: " + Thread.currentThread());
            int sum = 1;
            int r = (new Random()).nextInt(20);
            for (int j = 1; j < r; j++) {
                sum = sum * j;
            }
            Thread.sleep(10000);
            return sum;
        }).get();
        for (int i = 0; i < 10; i++) {
            int result5 = executor.submit(() -> {
                System.out.println("2: " + Thread.currentThread());
                int sum = 1;
                int r = (new Random()).nextInt(20);
                for (int j = 1; j < r; j++) {
                    sum = sum * j;
                }

                return sum;
            }).get();
        }

        executor.shutdown();
    }
}