写入标准输出与写入文件 [英] Writing to standard out vs writing to file

问题描述

这类似于：

打印到控制台与写入文件（速度）

我很困惑，因为有两个冲突答案。我写了一个简单的java程序

I was confused because there are two conflicting answers. I wrote a simple java program

 for(int i=0; i<1000000; i++){
       System.out.println(i);
 }

并以 / usr / bin / time运行-v java test 来测量输出到stdout的时间，然后我试过 / usr / bin / time -v java test> file 和 / usr / bin / time -v java>的/ dev / null的。写入控制台最慢（10秒）然后文件（6秒）和 / dev / null 最快（2秒）。为什么？

and ran it with /usr/bin/time -v java test to measure time to output to stdout, then I tried /usr/bin/time -v java test > file and /usr/bin/time -v java > /dev/null. Writing to console was slowest (10 seconds) then file (6 seconds) and /dev/null was fastest (2 seconds). Why?

推荐答案

因为写入控制台需要在每次写入内容时刷新屏幕，这需要时间。

Because writing to console needs to refresh the screen each time something is written, which takes time.

写入文件需要在磁盘上写入字节，这需要时间，但比刷新屏幕的时间要短。

Writing to a file needs to write bytes on disk, which takes time, but less time than refreshing the screen.

写入 / dev / null 不会在任何地方写任何内容，这会花费更少的时间。

And writing to /dev/null doesn't write anything anywhere, which takes much less time.

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