### This is a non-runnable code fragment
### only to show a general idea of threads pulling work
### from a common input queue and putting results on a
### common output queue.

use Threads::Queue;

my @all_inputs;  global data for all threads as read only

### Worker threads #####

my $thread_limit = 4;

my @threads;
push @threads, threads->create(sub{DoWork($workQueue, $doneQueue)}) for 1 .. $thread_limit;


foreach my $input ( @all_inputs )  #init the work queue with all inputs
{
    $workQueue->enqueue($input);
}

$workQueue->enqueue(undef) for 1 .. $thread_limit;  #"work finished" markers
                                                    #each thread will give up
                                                    #when it sees an undef

$workQueue->end();

$_->join() for @threads;  #waits for all threads to finish!

print "END of threading...\n";

####  Get results off of  Queue

my @results;
while ($doneQueue->pending() && ($_ = $doneQueue->dequeue()) )
{
   push (@results, $_); #results are pointers to array (AoA)
}

sub DoWork
{
   my ($workQueue, $doneQueue) = @_;
   
   while (my $input = $workQueue->dequeue()) 
   {   
      return unless defined ($input); #this ends this thread's job!!
      
      if ($input =~ m|/|)
      {
         $doneQueue -> enqueue([$input,'SKIPPING THIS ENTRY!']);
         next;
      }
      
      my $regex = get_regex_patterns ($input); 
      $regex =~ s/\(|\)//g;  #captured values not needed, only yes/no
        
      my @matches = grep{ m/$regex/ and $_ ne $input}@all_inputs;
 
      push (@matches,'') if @matches==0;
      
      $doneQueue -> enqueue([$call,@matches]);
   }
}