#include <iostream>
#include <unistd.h>
#include <sys/wait.h>
#include <cstdlib>
#include <ctime>
void random_task(int id) {         //race!
srand(time(0));
int delay=1+rand()%3;
std::cout<<"PID: " <<getpid()
<<"task " << id
<<" delay :"<< delay<< "s\n";
sleep(delay);
}

int main() {
int total_tasks=10;
int k=4;
int pipefd[2];
pipe(pipefd);

pid_t rootpid=getpid();

for (int w=0; w<k; w++)
fork();
if (getpid()!=rootpid)
{
    close(pipefd[1]);
    int task;
    while (read(pipefd[0], &task, sizeof(task))>0)
    {
    random_task(task);
    }
    close(pipefd[0]);
    _exit(0);
    }

close(pipefd[0]);
for (int t=0; t<total_tasks;t++) {
        write(pipefd[1], &t , sizeof(t));
        }
        close(pipefd[1]);
        while(wait(0) >0);
        std::cout<<" all tasks completed \n";
        return 0;
        }