Using select() with sockpair()

Hello everybody
I have run into a bit of trouble with my use of the select() function on some file descriptors generated with the sockpair() function.
Basically, I would like for the main process to have a number of sons, each of which will communicate with the former through a pair of sockets. Since I believe that some sons will take more time to generate their output, I would like for the father to gather that output asynchronously, meaning that he will first recieve data from the first son that finishes. I have simulated this artificially by making some sons have a time-consuming loop, but the problem is that the other sons all send their output correctly, whereas the sons that take a while to process end up not "becoming set" in the fd_set which corresponds to the select(), and the father never recieves their output (despite the fact that their write() function seems to have no problem writing to.. something).
I hope I've been able to describe the problem accurately:

Code:

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#include<stdio.h>
#include<fcntl.h>
#include<stdlib.h>
#include<sys/wait.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<errno.h>
#include <netinet/in.h>

#define MAX_FII 16
extern int errno;


int main(int argc, char * argv[])
{
    int socketi[MAX_FII][2], status;
    fd_set readfds,actfds;
    struct timeval tv;
    int ndfs;
    for(int i=0;i<10;++i)
    {
        if(socketpair(AF_UNIX,SOCK_STREAM,0,socketi[i])<0)
        {
            printf("eroare %d la socketpair!\n",errno);
        }
        status = fork();
        if(status)
        {

            //wait(NULL);
        }
        else
        {
            close(socketi[i][1]);
            char msg[20];
            bzero(msg,sizeof(msg));
            sprintf(msg,"%d",i);
            if(i%2){                                                  //this is the artificial loop, basically all the "odd" sons wil stall a bit
            for(int j=0;j<37500;++j)
              for(int k=0;k<15000;++k);
            qDebug("We shall write %d !!",i);
        }
            int car;
            if((car=write(socketi[i][0],msg,sizeof(msg)))<0)
            {
                printf("eroare %d la write!\n",errno);
            }
            else
            {
//                if(i==1)
//                    printf("%d ",car);
            }
            close(socketi[i][0]);
            qDebug(" %d",car);    // for all 10 sons the value of the number of characters written is 20
            exit(1);
        }
    }

    FD_ZERO(&readfds);
    ndfs=0;
    tv.tv_sec=2;
    tv.tv_usec=0;

    for(int i=0;i<10;++i)
    {
     
        close(socketi[i][0]);
        ndfs = (ndfs<socketi[i][1])?socketi[i][1]:ndfs;
        FD_SET(socketi[i][1],&readfds);
    }

    int counter = 0;
    while(counter<10)
    {

        int nrselect;
        if((nrselect=select(ndfs+1,&readfds,NULL,NULL,&tv)) < 0)
        {
            printf("eroare %d la select\n",errno);
        }
   

        for(int i=0;i<10;++i)
        {
            if(FD_ISSET(socketi[i][1],&readfds))
            {

              char msg[512];
              bzero(msg,sizeof(msg));
              if(read(socketi[i][1],msg,512)<0)
              {
                  printf("eroare %d la read! \n",errno);
              }
              qDebug("%s !",msg);
              ++counter;
              close(socketi[i][1]);
              FD_CLR(socketi[i][1],&readfds);
              qDebug("%d ",readfds);
            }

        }

       
}

    return 0;//app.exec();
}

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I'm working under Linux, using the QT framework. the output produced is:

Code:

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0 !
2 !
4 !
6 !
8 !
We shall write 5 !!
We shall write 9 !!
We shall write 1 !!
We shall write 3 !!
We shall write 7 !!
<<here the program stalls indefinitely>>

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which means that 0,2,4,6,8 got received correctly, and 5,9,1,3,7 never got read()

I would appreciate any help. Thank you.