use IO::Handle;

use Socket;

use threads;

use IO::Socket::INET;

open(pctxt,'./pc.txt')||die "error open $!";


while($read_data = <pctxt>)
{
        chomp;
        $read_data=~s/\s//g;
        $read_data=~s/" "//g;
        thread($read_data);
}

close(pctxt);


sub thread
{
    my $net = shift;
    my @ip = (1..255);
    my $port = 12345;
    my $thr0 = threads->new(\\&scan, "$net@ip[0..63]", $port);
    my $thr1 = threads->new(\\&scan, "$net@ip[64..127]", $port);
    my $thr2 = threads->new(\\&scan, "$net@ip[128..191]", $port);
    my $thr3 = threads->new(\\&scan, "$net@ip[192..254]", $port);
    $thr0->join();
    $thr1->join();
    $thr2->join();
    $thr3->join();
}



sub scan
{
        my (@hosts, $port) = @_;
       foreach my $host (@hosts)
        {
                  my $socket = new IO::Socket::INET
                  (
                            PeerHost => $host,
                            PeerPort => $port,
                            Proto    => "tcp",
                    );
                if($socket)
                {
                       print $port,"is  open!\\n";
                       $socket->close();
                }

         }
}
[download]

####################################################
After running,prompt Errors as following;
thread failed to start: Not a CODE reference at pcmnt.pl line 28.
thread failed to start: Not a CODE reference at pcmnt.pl line 29.
thread failed to start: Not a CODE reference at pcmnt.pl line 30.
thread failed to start: Not a CODE reference at pcmnt.pl line 31