So I've been away from perl for a long time, now I have the chance to get back and I'm jumping all in. But to the problem, I've been playing with a program to test some equipment and essentially it'll fork a bunch of children and have them do a task eg. check a webpage. The parent process writes the webpage url for the child to check. This I all have working fine based on some examples from Proc::Fork. What I'm having alot of trouble with is getting the children to reply back to the parent so that I can aggregate stats and such. I have a feeling I'm not reading from the pipes properly.
I've boiled down the code to the basics. I've commented out the parts that I believe are wrong. 
#!/usr/bin/perl
 use strict;
 use Proc::Fork;
 use IO::Pipe;

 my $num_children = shift;    # How many children we'll create
 my %children;            # Store connections to them
 my %childrenin;            # Store connections from children
 $SIG{CHLD} = 'IGNORE';   # Don't worry about reaping zombies

 # Spawn off some children
 for my $num ( 1 .. $num_children ) {
     # Create a pipe for parent-child communication
     my $pipe = IO::Pipe->new;
     my $pipein = IO::Pipe->new;

     # Child simply echoes data it receives, until EOF
     run_fork {
                child {
                print "[$num] Child Start\n";
                $pipe->reader;
                $pipein->writer;
                my $data;
                my $dataout = $pipein;
                while ($data = <$pipe>)
                {
                chomp($data);
                print STDERR  "Child [$num]: $data \n";
                print $dataout  "[$num]: $data \n";
                }
                exit;
                }
        };

     # Parent here
     $pipe->writer;
     $children{$num} =  $pipe;

     $pipein->reader;
     $childrenin{$num} = $pipein;
 }

 # Send some data to the kids
 for my $i ( 1 .. $num_children ) {
     my $child = $children{$i};
     print $child "Line 1\n";
 }

# Read data from children
# this is where I believe I'm going wrong.

=comment
 for my $i ( 1 .. $num_children ) {
        my $childin = $childrenin{$i};
        my $datain;
        while ( $datain = <$childin> )
        {
                print "[Parent] $datain \n";;
        }
}
=cut

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In reply to When forking how can the child talk back to the parent? by Felix2000

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