什么在2次迭代时使用内存？

Question

我创建了一个函数来测试GC并查看内存使用情况。结果很奇怪。

内存分析类：

public class MemoryAnalizer {

private static NumberFormat nf = NumberFormat.getNumberInstance(Locale.GERMAN);
private static DecimalFormat df = (DecimalFormat) nf;
static long heapSize;
static long heapMaxSize;
static long heapFreeSize;
static long used;

public static void analize()
{
    heapSize = Runtime.getRuntime().totalMemory();
    heapMaxSize = Runtime.getRuntime().maxMemory();
    heapFreeSize = Runtime.getRuntime().freeMemory();
    used = heapSize - heapFreeSize;

    System.out.println("MemoryAnalitics: [ Used: " + df.format(used / 1000) + " Free: " + df.format(heapFreeSize / 1000) + " HeapSize: " + df.format(heapSize / 1000) + " | Max HeapSize: " + df.format(heapMaxSize / 1000) + " (KBs)]");
}
}

在GC调用之前和之后调用内存分析的Main函数：

private static MemoryAnalizer memory = new MemoryAnalizer();

public static void main(String argv[])
{
    while (true)
    {
        System.out.println();
        memory.analize();
        System.gc();
        memory.analize();
    }
}

生成的打印件显示以下结果：

MemoryAnalitics: [ Used: 977 Free: 124.852 HeapSize: 125.829 | Max HeapSize: 1.860.698 (KBs)]
MemoryAnalitics: [ Used: 305 Free: 125.523 HeapSize: 125.829 | Max HeapSize: 1.860.698 (KBs)]

MemoryAnalitics: [ Used: 977 Free: 124.852 HeapSize: 125.829 | Max HeapSize: 1.860.698 (KBs)]
MemoryAnalitics: [ Used: 305 Free: 125.523 HeapSize: 125.829 | Max HeapSize: 1.860.698 (KBs)]

MemoryAnalitics: [ Used: 977 Free: 124.852 HeapSize: 125.829 | Max HeapSize: 1.860.698 (KBs)]
MemoryAnalitics: [ Used: 305 Free: 125.523 HeapSize: 125.829 | Max HeapSize: 1.860.698 (KBs)]

什么可以解释每个while循环之间增加600 KB的内存？