Hi all,

I would like to clarify whether using pipe with more than one child process is safe or not. For instance, I would like to fork numerous child process, each having to pass continuous data to its parent process. A simple working version of what I am trying to do is below: 

 
use IO::Socket;
use IO::Handle;
pipe(READER, WRITER);   
WRITER->autoflush(1);
$| = 1;

for ($i=0;$i<10;$i++)
{
    if (!defined($kidpid = fork())) 
    {
        # fork returned undef, so failed
        die "cannot fork: $!";

    } elsif ($kidpid == 0) {

        close READER;
        
        for (my $p=0;$p<10;$p++)
        {
            sleep(1);
            print WRITER "$$: I am sending mum this message \n";
        }
        close WRITER;

        exit;
    } 
}

[download]

Since the child is writing to the parent using  print "data\n" and the parent is reading upto the newline character each time, will the "data" always be correct or is there a possiblity that two child's print data will collide and thus the parent will receive the result of a jumbled effect of the children's message with one read?

For example, I always want the parent to receive

my PID: I am sending mum this message

Many thanks in advance for your help.

Gmong

In reply to Using pipe with more than one child process by Anonymous Monk

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