use strict;
use warnings;

use threads;
use Thread::Semaphore;
use Time::HiRes qw(time);

my $iterations = 100;
my $chunksize  = 50;
my $threads    = 5;
my $results    = "s.txt";

my $s = Thread::Semaphore->new($threads);

my %data = ();

foreach ('a'..'z') {
   $data{$_} = $_ x 200;
}

test();

sub test {
   my $t = time;
   manager();
   printf "duration: %0.02f secs.\n", time - $t;
}

sub work {
   my ($data) = @_;
   my @ret = ();

   foreach my $chunk (@$data) {
      my %output = ();

      foreach my $key (keys %$chunk) {
         if ($key eq '.') {
            $output{$key} = $$chunk{$key};
            next;
         }
         my $val = $$chunk{$key};
         my $uc = uc($key);
         $val =~ s/$key/$uc/g;
         $output{$key} = $val;
      }

      push @ret, \%output;
   }

   my $buf = '';

   foreach my $data (@ret) {
      foreach my $key (sort keys %$data) {
         $buf .= $$data{$key};
      }
      $buf .= "\n";
   }

   $s->up();

   return $buf;
}

sub manager {
   my @q; open my $fh, '>', $results or die "open error: $!\n";

   foreach my $a (1..$iterations) {
      my @chunk = ();

      foreach my $b (1..$chunksize) {
         my %_data = %data;
         $_data{'.'} = $a * $b;
         push @chunk, \%_data;
      }

      $s->down();

      push @q, threads->create('work', \@chunk);

      while (@q && $q[0]->is_joinable) {
         my $output = shift(@q)->join();
         print {$fh} $output;
      }
   }

   while (@q) {
      my $output = shift(@q)->join();
      print {$fh} $output;
   }

   close $fh;
}