In addition to the missing comma, the following line is nonsense:

my %hash = $$hashref;
[download]

You can either make a complete copy of the hash by doing

my %hash = %$hashref;
[download]

or more efficiently, just delete that line and always directly use the hashref, eg

foreach my $key (keys %$hashref) {
    my $weight = $hashref->{$key};
    ...
[download]

Dave.