Question

我是fork（）和创建4个同时运行的子进程（忙于工作），但父进程需要等到所有子进程退出。我觉得我可以用更好的方式编码...任何建议或看起来好吗？（我需要保留2种形式和主要格式）

using namespace std;

void simulateBusyWork(char, pid_t);
pid_t performFork();

int main()
{
    srand(time(NULL));
    performFork();
    return 0;
}

pid_t performFork() {

    pid_t pid;

    //create four child processes
    for (int i = 0; i < 4; ++i) {
        pid = fork();
        if (pid<0) {
            continue;
        } else if (pid == 0) {
            break;
        } 
    }

    //fork failed
    if (pid < 0) {
        fprintf(stderr, "Fork failed./n"); 
        return 1;
    }

    //child process do busy work
    else if (pid == 0) {
        cout << "A child process with PID " << getpid() << " was created." << endl;
        pid = getpid();
        simulateBusyWork('C', pid);
        _exit(0);
    }

    //parent process do busy work
    else if(pid > 0){
        simulateBusyWork('P', getpid());

        //parent process waits for children to exit
        int status, exited;
        //print which child has exited
        for (int i = 0; i < 4; i++) {
            exited = waitpid(-1, &status, 0);
            cout << "P" << getpid() << ": Process " << exited << " has exited." << endl;
        }
    }



    return pid;
}

void simulateBusyWork(char ch, pid_t pid) {

    for (int i=0 ; i < 4; i++) {        
        cout << ch << pid << ": " << i << endl;
        //if (i < 4)
            sleep(1);
    }
    cout << "Process " << ch << pid << " has finished its work." << endl;
}

Answer 1

from django.db.models import * from django.contrib.auth.models import User, Group from django.db.models.signals import post_save class MyUser(Model): user = OneToOneField(User, primary_key=True) Volume = IntegerField(default=5*1024*1024) def create_profile(sender, instance, created, **kwargs): if created: profile, created = MyUser.objects.get_or_create(user=instance) post_save.connect(create_profile, sender=User, dispatch_uid="create_profile")：

电话man waitpid是等效的到：
wait(&status)

所以你可以简化一下。

fork（）使用c ++并创建父级的4个子级

1 个答案: