多线程快速排序比Java中的正常快速排序慢

Question

Im比较快速排序(正常，具有递归性(和线程快速排序(使用线程(。我发现普通快速排序比线程快速排序更快。这是对的吗？感觉我做错了什么。

这是代码：

public class QuickSort implements SortAlgorithm {
public void Sort(Integer[] array) {
Sort(array, 0, array.length-1);
}
private void Sort(Integer[] array, Integer low, Integer high) {
if (low < high) {
Integer pivot = partition(array, low, high);
Sort(array, low, pivot-1);
Sort(array, pivot+1, high);
}
}
private Integer partition(Integer[] array, Integer low, Integer high) {
Integer pivot = array[high];  
Integer i = (low-1);
for (Integer j=low; j<high; j++) 
if (array[j] < pivot) { 
i++; 
Integer temp = array[i]; 
array[i] = array[j]; 
array[j] = temp; 
} 
Integer temp = array[i+1]; 
array[i+1] = array[high]; 
array[high] = temp; 
return i+1; 
}
}

public class ThreadsQuickSort extends Thread implements SortAlgorithm {
private Integer low, high;
private Integer[] array;
public ThreadsQuickSort() {
;
}

public ThreadsQuickSort(Integer[] array, Integer low, Integer high) {
this.array = array;
this.low = low;
this.high = high;
}
public void run() {
Sort(array, low, high);
}
public void Sort(Integer[] array) {
Sort(array, 0, array.length - 1);
}
private void Sort(Integer[] array, Integer low, Integer high) {
if (low < high) {
Integer pivot = partition(array, low, high);
ThreadsQuickSort lowQSort = new ThreadsQuickSort(array, low, pivot - 1);
lowQSort.start();
ThreadsQuickSort highQSort = new ThreadsQuickSort(array, pivot + 1, high);
highQSort.start();
try {
lowQSort.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
try {
highQSort.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
private Integer partition(Integer[] array, Integer low, Integer high) {
Integer pivot = array[high];  
Integer i = (low-1);
for (Integer j=low; j<high; j++) 
if (array[j] < pivot) { 
i++; 
Integer temp = array[i]; 
array[i] = array[j]; 
array[j] = temp; 
} 
Integer temp = array[i+1]; 
array[i+1] = array[high]; 
array[high] = temp; 
return i+1; 
}
}

主函数使用这两种算法对10000个项目的数组进行排序，并获取它们的执行时间。得到这个输出：

Single array sorted in 11 ms
The array was successfully sorted
Threaded array sorted in 6378 ms
The array was successfully sorted

我的问题是，这是否编码良好，输出是否在预期范围内。这与线程快速排序的实现无关。

Answer 1

~70微创建和每个线程的切换。

线程的总和应该在20000-1左右给出20000*70us=1400000 us=1400ms=1.4s

因此，这几乎是意料之中的事。