CODEWITHSUNDEEP
processforkparent-childwait
user3026752
user3026752

Reputation: 1

Run child processes in parallel with fork

I need to create "n" child processes and they have to sleep a random number of seconds, and the parent process have to advise when any child process has finished. The problem is that each child process runs one after other and I need them to work in parallel. (In the code I'm just creating 3 children.)

#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/wait.h>

int main(void)
{
 pid_t pid;
 int x,zeit,status,w,n=0;

 for(x=1;x<=3;x++)
 {
 pid=fork();  
    n++;
    srand(time(NULL));
  if(pid)
  {

    w=wait(&status);

   printf("Process %d finished in %d seconds (Dad:%d cuenta %d)\n",w,WEXITSTATUS(status),getppid(),n);

  }
  else
  {
   int n;
   zeit=rand()%3+1;
   sleep(zeit);
   exit(zeit);

  }

 }
exit(0);
 return 0;
}

Upvotes: 0

Views: 2357

Answers (1)

Sam I am says Reinstate Monica
Sam I am says Reinstate Monica

Reputation: 31204

You're explicitly waiting for each process to finish before you start the next one

for(x=1;x<=3;x++)
{
  pid=fork();  
  n++;
  srand(time(NULL));
  if(pid)
  {  
    w=wait(&status);    
    printf("Process %d finished in %d seconds (Dad:%d cuenta %d)\n",
           w, WEXITSTATUS(status), getppid(), n);
    ...
  }

If you want them to run in parallel, you're going to have to make 3 different processes, and start them off before you wait for any one of them to finish.

Upvotes: 2

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