这个可以程序主要测试高级并发服务器程序怎样写会避免僵尸进程？

#include <unistd.h>  
#include <stdio.h>  
#include<stdlib.h>
#include<signal.h>
int main(void)  
{  //signal(SIGCHLD, SIG_IGN);
   int i=0;  
   printf("i son/pa ppid pid  fpid
");  
   //ppid指当前进程的父进程pid  
   //pid指当前进程的pid,  
   //fpid指fork返回给当前进程的值  
   while(1){  
   sleep(1);                           //之所以加入这个时间是因为，容易看出程序的变化，不然根本看不出变化，连鼠标都懂不了！
       pid_t fpid=fork();  
       if(fpid==0)  
           {printf("%d child  %4d %4d %4d
",i,getppid(),getpid(),fpid);
            //return 0; //这两个效果一样的！
            exit(0);
            } 
         }  
return 0;  
}  
[root@linux Desktop]# gcc b.c
[root@linux Desktop]# ./a.out
i son/pa ppid pid  fpid
0 child  16980 16981    0
0 child  16980 16982    0
0 child  16980 16983    0
0 child  16980 16985    0
0 child  16980 16988    0
0 child  16980 16990    0
0 child  16980 16991    0
0 child  16980 16993    0
0 child  16980 16995    0
0 child  16980 16996    0
^C
[root@linux Desktop]# 

[root@linux Desktop]# ps aux | grep -w 'Z'               //产生了好多僵尸进程了
root     16981  0.0  0.0      0     0 pts/2    Z+   20:38   0:00 [a.out] <defunct>defunct某些系统中用它来作为僵尸的标志
root     16982  0.0  0.0      0     0 pts/2    Z+   20:38   0:00 [a.out] <defunct>
root     16983  0.0  0.0      0     0 pts/2    Z+   20:38   0:00 [a.out] <defunct>
root     16985  0.0  0.0      0     0 pts/2    Z+   20:38   0:00 [a.out] <defunct>
root     16987  0.0  0.0   4340   804 pts/3    S+   20:38   0:00 grep -w Z
[root@linux Desktop]# 

当把signal(SIGCHLD, SIG_IGN);这行代码加上时输出结果如下：
[root@linux Desktop]# gcc b.c
[root@linux Desktop]# ./a.out
i son/pa ppid pid  fpid
0 child  17135 17136    0
0 child  17135 17137    0
0 child  17135 17139    0
0 child  17135 17140    0
0 child  17135 17141    0
0 child  17135 17142    0
0 child  17135 17145    0
0 child  17135 17147    0
0 child  17135 17150    0
0 child  17135 17151    0
0 child  17135 17152    0
^C
[root@linux Desktop]#                     //没有僵尸进程产生
[root@linux Desktop]# ps aux | grep -w 'Z'
root     17144  0.0  0.0   4336   796 pts/3    S+   20:42   0:00 grep -w Z
[root@linux Desktop]# ps aux | grep -w 'Z'
root     17149  0.0  0.0   4336   792 pts/3    S+   20:42   0:00 grep -w Z
[root@linux Desktop]# 

<defunct>