为什么我的流复制过程性能稳步下降

Question

这段代码在复制大文件时运行得越来越慢。我做错什么了吗？

    InputStream ms2 = new BufferedInputStream(new FileInputStream("/home/fedd/Videos/homevid.mp4"));
    OutputStream fos2 = new BufferedOutputStream(new FileOutputStream("testfile2.mp4", true));

    try {
        int byt;
        int i = 0;
        long time = System.currentTimeMillis();
        while ((byt = ms2.read()) != -1) {
            fos2.write(byt);
            i++;
            if (i > 100000) {
                i = 0;
                long took = System.currentTimeMillis() - time;
                System.out.println("100000 bytes took " + took + " milliseconds which means " + (100000000 / took) + " bytes per second");
            }
        }
        fos2.close();
        ms2.close();
    } catch (Exception e) {
        throw new RuntimeException(e);
    }

我的Java是：

OpenJDK10.0.2 2018-07-17OpenJDK运行时环境（构建10.0.2 13-Ubuntu-1ubuntu0.18.04.4）

OpenJDK 64位服务器VM（构建10.0.2 13-Ubuntu-1ubuntu0.18.04.4，混合模式）

Answer 1

由于计算错误，您的性能会下降。对于第二个块，您是从第二个块的大小计算每秒字节数，但从两个块的时间计算。尝试添加time=System。currentTimeMillis（） 在long take=

Answer 2

每次比较后，你都需要重置基本“时间”。尝试使用以下方法：

if (i > 100000) {
    i = 0;
    long took = System.currentTimeMillis() - time;
    time = System.currentTimeMillis();
    System.out.println("100000 bytes took " + took + " milliseconds which means " + (100000000 / took) + " bytes per second");
}