child started IO::Socket::INET=GLOB(0x204aeb8)
child read failed: Invalid argument at E:\Perls\sock_hop.pl line 63.
parent started IO::Socket::INET=GLOB(0x176541c)
parent sending
parent sending
parent sending
parent write failed: Invalid argument

##</code><code>##

use strict;
use warnings;

use IO::Socket;

sub process;
sub parent;
sub child;

use vars qw[$PARENT $CHILD];

process;
exit;

sub process {

   $PARENT = IO::Socket::INET->new(
                 Type => SOCK_STREAM,
                 Proto => 'tcp',
                 LocalHost => 'localhost',
                 LocalPort => 9969,
                 Listen => 5,
                 );
   die "parent socket failed: $!\n" unless defined $PARENT;
    
   $CHILD = IO::Socket::INET->new(
                 Type => SOCK_STREAM,
                 Proto => 'tcp',
                 PeerAddr => 'localhost',
                 PeerPort => 9969,
                 );
   die "child socket failed: $!\n" unless defined $CHILD;
    
   if (my $pid = fork()) {
      close $PARENT;
      parent;
   } else {
      die "fork failed: $!\n" unless defined $pid;
      close $CHILD;
      child;
   }

}

sub parent {

   print STDERR "parent started $CHILD\n";

   while (1) {
      print STDERR "parent sending\n";
      print $CHILD "Hello from parent\n" or die "parent write failed: $!\n";
      sleep 2;
   }
    
}

sub child {

   print STDERR "child started $PARENT\n";

   while (1) {
      my $line = readline ($PARENT);
      die "child read failed: $!" unless defined $line;
      print STDERR $line;
   }

}