use POSIX;
use IO::Socket;
use IO::Select;

my $udp    = new IO::Socket::INET(LocalAddr => $interface,'LocalPort' => $port, 'Proto' => 'udp') or die $!;

my $sockin = new IO::Select;
my $sockout = new IO::Select;
my $sockerr = new IO::Select;

$sockin->add($udp);

my ($read, $write, $err) = ([],[],[]);

while(1) {
    ($read, $write, $err) = IO::Select->select($sockin, $sockout, $sockerr, 1);
    for my $sock (@$read) {
         my $data;
         $sock->recv($data, 1024 * 64, 0);

         next if $! == EAGAIN() || $! == EWOULDBLOCK(); #---- $! is populated by IO::Socket

         # client request in $data ---- process as you want

    }
    for my $sock (@$write) {
# not important
    }
    for my $sock (@$err) {
# clean up any errors
    }
}