在Linux中四次fork()之后创建了多少个进程? [英] How many processes are created after four fork() in Linux?

问题描述

我在操作系统教科书上看到一个愚蠢的问题.问题如下:
假定所有fork系统调用均成功.执行下面所示的程序后.屏幕上有几行?
我假设每个fork调用都会使进程加倍，因此结果应该是创建了16个进程.但是，当我从课本中键入相同的代码时，我得到了30行.结果和代码如下:
http://imgur.com/zrdOP0X

I have a dumb question seeing on the Operating system textbook. The question is below:
Assume that all fork system calls are successful.After executing program shown below. How many lines are on the screen?
I assume that every fork call doubles the processes, so the result should be 16 process are created. But when I type the same code from the textbook, I got 30 lines. Here is the result and the code:
http://imgur.com/zrdOP0X

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int main(){
    fork();
    printf("After fork1\n");
    fork();
    printf("After fork2\n");
    fork();
    printf("After fork3\n");
    fork();
    printf("After fork4\n");
}

推荐答案

结果应如下所示:

fork1 fork2 fork3 fork4 fork4 fork3 fork4 fork4
fork2 fork3 fork4 fork4 fork3 fork4 fork4 fork1 fork2 fork3 fork4 fork4 fork3 fork4 fork4
fork2 fork3 fork4 fork4 fork3 fork4 fork4

fork1 fork2 fork3 fork4 fork4 fork3 fork4 fork4
fork2 fork3 fork4 fork4 fork3 fork4 fork4 fork1 fork2 fork3 fork4 fork4 fork3 fork4 fork4
fork2 fork3 fork4 fork4 fork3 fork4 fork4

(空格仅用于更好地阅读)

(the spaces are only for better reading)

这篇关于在Linux中四次fork()之后创建了多少个进程?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！