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fork_test.cpp
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69 lines (65 loc) · 1.85 KB
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#include <unistd.h>
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
int global = 10;
// 子进程只是把内存复制过去了 二者拥有的并不是同一份
// 但是并不是fork之后，子进程又要重新开辟一个和父进程同等大小的内存空间，二者遵循读时共享，写时复制的策略
void signal_handle(int signo)
{
switch (signo)
{
case SIGINT:
printf("signal SIGINT was occurred in process:%d!\n", getpid());
break;
case SIGALRM:
printf("signal SIGALRM was occurred in process %d!\n", getpid());
break;
default:
break;
}
}
int main(int argc, char **argv)
{
int local = 4; // 局部变量
int pid = fork();
signal(SIGALRM, signal_handle);
alarm(2);//在fork之前调用的那么fork出来的子进程也会拥有这个定时器状态
if (pid == 0)
{ // 子进程
printf("子进程中：global,local:%d,%d\n", global, local);
// 子进程修改全局变量和局部变量
global += 10;
local += 10;
printf("子进程开始休眠s\n");
sleep(2);
printf("子进程休眠结束\n");
printf("子进程中：global,local:%d,%d\n", global, local);
sleep(5);
}
else
{ // 父进程
printf("父进程开始休眠s\n");
sleep(1);
printf("父进程休眠结束\n");
printf("父进程中：global,local:%d,%d\n", global, local);
global = -1;
local = -10;
alarm(3);
sleep(5);
}
return 0;
}
/**
运行结果:
父进程开始休眠s
子进程中：global,local:10,4
子进程开始休眠s
父进程休眠结束
父进程中：global,local:10,4
signal SIGALRM was occurred in process 2121!
子进程休眠结束
子进程中：global,local:20,14
signal SIGALRM was occurred in process 2120!
*/