You could try something like this.

#! perl -slw
use strict;
use threads;
use threads::shared;;
use LWP::Simple;
use constant MAX_THREADS => 3;

chomp( my @urls = <DATA> );

my %store :shared;
my $threads :shared;
for my $page ( @urls ) {
    async {
        $store{ $page } = get( 'http://' . $page ) or die "Failed to g
+et $page";
        print "Loaded $page";
    } and $threads++;
    if( $threads > MAX_THREADS ) {
        if( my @joinable = threads->list(threads::joinable) ) {
            $_->join for @joinable;
            $threads -= @joinable;
        }
        else {
           sleep 1;
       }
    }
}
$_->join for threads->list;

printf "Press enter to see the data gathered"; <STDIN>;

print "*** $_ ***\n$store{ $_ }\n\n" for keys %store;

__END__
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