open my $h_data, "<", "file-1" or die $!;
open my $h_id,   "<", "file-2" or die $!;
my $data = <$h_data>;
my $id = <$id>;
while (defined $data && defined $id) {
    no warnings 'numeric';
    given ($data <=> $id) {
        when (-1) {$data = <$h_data>}
        when ( 0) {print $data; $data = <$h_data>; $id = <$h_id>;}
        when ( 1) {$id = <$h_id>;}
    }
}