use threads;
use Thread::Queue;

my $work_queue = Thread::Queue->new;
$work_queue->enqueue($_)  for ($start .. $end); #Fill our work queue

my $work_queue = Thread::Queue->new;

my $fetch_thread  = threads->new( \&fetch, $work_queue, $fetched_queue);

sub fetch {
   my $input_queue = shift;
   my $output_queue = shift;

   while ( my $fetch_this = $input_queue->dequeue ) {
      #Get content, put in scalar
      $output_queue->enqueue($content);

      last if ($input_queue->pending == 0)
   }
}

my $processed_queue = Thread::Queue->new;
my $process_thread  = threads->new( \&process, $fetched_queue, $processed_queue );

sub process {
   my $input_queue = shift;
   my $output_queue = shift;

   while ( my $process_this = $input_queue->dequeue ) {
      #process data, put in scalar
      $output_queue->enqueue($content);

      last if ($input_queue->pending == 0)
   }
}

while (my $processed_data = $processed_queue->dequeue) {
   #Assemble into final output

   last if ($input_queue->pending == 0)
}

#Make final output