如何在 20 秒后终止 c 程序
[英]How to terminate a c program after 20 seconds
问题描述
I am trying to terminate my c program with multiple functions after 20 seconds (kill all child and parent processes, close files).
我试图在 20 秒后终止具有多种功能的 c 程序（杀死所有子进程和父进程，关闭文件）。 I tried alarm(), itimer(), clock().我试过闹钟（），定时器（），时钟（）。 It works when we only have a main and a handler function.当我们只有一个 main 和一个处理程序 function 时，它可以工作。 clock() restarts from 0 in every function even if I keep the variables global.即使我将变量保持在全局范围内，clock() 也会在每个 function 中从 0 重新开始。
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <time.h>
#include <stdlib.h>
#include <dirent.h>
#include <stdio.h>
#include <string.h>
#include <getopt.h>
#include<stdbool.h>
#include <ctype.h>
#include<sys/wait.h>
#include<signal.h>
#include <sys/mman.h>
#include<sys/time.h>
#define INTERVAL 2
int t=0;
void display_message()
{
printf("In the handler");
//kill(0,SIGKILL);
t=1;
}
void calling2()
{
signal(SIGALRM, display_message);
sleep(3);
}
void calling()
{
signal(SIGALRM, display_message);
alarm(2);
int i;
for(i=0;i<3;i++)
{
//printf("\nStarting fork for loop i=%d \n",i);
pid_t pID = fork();
if (pID == 0) // child
{
calling2();
if(t==1)
{
printf("we have exceeded 2 seconds killing the process");
kill(0,SIGKILL);
exit(0);
}
exit(0);
kill(pID,SIGKILL);
}
else if(pID>0)
{
// printf("\nhello from the father");
if(t==1)
{
printf("killing the process");
kill(0,SIGKILL);
exit(0);
}
printf("\nhello from the father");
}
}
}
As you can see I tried calling signal from different functions so it can catch the signal and the handler can execute but the handler is never executed.如您所见，我尝试从不同的函数调用信号，以便它可以捕获信号并且处理程序可以执行，但处理程序永远不会执行。
EDIT: Tried this again编辑：再试一次
# include <unistd.h>
# include <sys/types.h>
# include <sys/stat.h>
# include <time.h>
# include <stdlib.h>
# include <dirent.h>
# include <stdio.h>
# include <string.h>
# include <getopt.h>
# include<stdbool.h>
# include <ctype.h>
# include<sys/wait.h>
# include<signal.h>
# include <sys/mman.h>
# include<sys/time.h>
# define INTERVAL 2
int t=0;
void display_message()
{
kill(0,SIGKILL);
t=1;
}
void calling2()
{
sleep(3);
}
void calling()
{
signal(SIGALRM, display_message);
int i;
for(i=0;i<3;i++)
{
pid_t pID = fork();
if (pID == 0) // child
{
calling2();
if(t==1)
{
printf("killing the process");
kill(0,SIGKILL);
exit(0);
}
exit(0);
}
else if(pID>0)
{
if(t==1)
{
printf("killing the process");
kill(0,SIGKILL);
exit(0);
}
printf("\nhello from the father");
}
}
}
int main()
{
signal(SIGALRM, display_message);
alarm(2);
calling();
}
O/P:
hello from the father
hello from the father
hello from the father
hello from the father
hello from the father
hello from the father
error: Failed with return code 22
1 个解决方案
解决方案1
0 2019-09-19 07:11:03
Main problem is your main thread is finished before alarm signal is handled.主要问题是您的主线程在处理警报信号之前完成。 You must let it live at least until alarm signal is delivered.您必须至少让它存活，直到发出警报信号。 Also as Jonathan Leffler adviced good indentation/spacing is really helpful.此外，正如 Jonathan Leffler 所建议的那样，良好的缩进/间距确实很有帮助。
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <time.h>
#include <stdlib.h>
#include <dirent.h>
#include <stdio.h>
#include <string.h>
#include <getopt.h>
#include <stdbool.h>
#include <ctype.h>
#include <sys/wait.h>
#include <signal.h>
#include <sys/mman.h>
#include <sys/time.h>
#define INTERVAL 2
int t=0;
void display_message()
{
kill(0,SIGKILL);
t=1;
}
void calling2()
{
sleep(3);
}
void calling()
{
signal(SIGALRM, display_message);
int i;
for(i=0;i<3;i++)
{
pid_t pID = fork();
if (pID == 0) // child
{
calling2();
if(t==1)
{
printf("killing the process");
kill(0,SIGKILL);
exit(0);
}
exit(0);
}
else if(pID>0)
{
if(t==1)
{
printf("killing the process");
kill(0,SIGKILL);
exit(0);
}
printf("\nhello from the father");
}
}
}
int main()
{
signal(SIGALRM, display_message);
alarm(2);
calling();
// wait until alarm callback before terminating main thread
sleep(100);
}
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