Java 関数における再帰呼び出しとマルチスレッドの関係は何ですか?

public class Factorial {

    public static int factorial(int n) {
        if (n == 1) {
            return 1;
        } else {
            return n * factorial(n - 1);
        }
    }

}

Main Thread: factorial(5)
New Thread: factorial(4)
New Thread: factorial(3)
New Thread: factorial(2)
New Thread: factorial(1)

public class ParallelizeTask {

    public static void main(String[] args) {
        List<Object> data = ...;

        // 使用递归函数将任务分解
        parallelize(data, 0, data.size() - 1);
    }

    public static void parallelize(List<Object> data, int start, int end) {
        if (start >= end) {
            return;
        }

        int mid = (start + end) / 2;
        
        // 创建新线程并行执行任务
        Thread left = new Thread(() -> parallelize(data, start, mid));
        Thread right = new Thread(() -> parallelize(data, mid + 1, end));

        left.start();
        right.start();

        // 等待线程完成
        try {
            left.join();
            right.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

}