use Coro                          qw( async );
use Coro::Channel                 qw( );
use LWP::Protocol::AnyEvent::http qw( );
use LWP::UserAgent                qw( );

my $num_workers = 10;

my $q = Coro::Channel->new();

my @threads;
for (1..$num_workers) {
   push @threads, async {
      my $ua = LWP::UserAgent->new();
      $ua->protocols_allowed([qw( http https )]);
      while (my $url = $q->get()) {
         my $response = $ua->get($url);
         ...
      }
   }
}

while (my $url = get_next_url()) {
   $q->put($url);
}

$q->shutdown();
$_->join() for @threads;