use strict;
use warnings;
use IO::Socket::INET;

$|++;

my $socket = IO::Socket::INET->new(
   LocalHost  => '127.0.0.1',
   LocalPort  => 50010,
   Type       => SOCK_STREAM,
   Listen     => 1000,
   Reuse      => 1,
) or die "server: can't open socket over port 50010";

warn "server $$ initialized\n";

for (0..4) {
   my $pid = fork;
   last unless $pid;
   warn "server $pid forked\n";
}

while (my $client = $socket->accept()) {
   my $pid = <$client>;
   chomp($pid);
   warn "Server $$ received request from: $pid\n";
   close($client);
}

close($socket);

use strict;
use warnings;
use IO::Socket::INET;

$|++;

warn "Client $$ initialized\n";

for (0..4) {
   my $pid = fork;
   last unless $pid;
   warn "Client $pid forked\n";
}

sleep 3;

while ( 1 ) { 
   my $socket = IO::Socket::INET->new(
      PeerAddr => '127.0.0.1',
      PeerPort => 50010,
      Proto    => 'tcp',
      Type     => SOCK_STREAM,
   ) or die "client: can't connect to 127.0.0.1:50010";

   warn "Client $$ connected to server\n";
   print $socket "$$\n";
   close($socket);
   sleep 1;
}