# from MCE docs: https://metacpan.org/pod/MCE
use MCE::Loop;
 
MCE::Loop::init { max_workers => 8, use_slurpio => 1 };
 
my $pattern  = 'something';
my $hugefile = 'very_huge.file';
 
my @result = mce_loop_f {
   my ($mce, $slurp_ref, $chunk_id) = @_;
 
   # Quickly determine if a match is found.
   # Process the slurped chunk only if true.
 
   if ($$slurp_ref =~ /$pattern/m) {
      my @matches;
 
      # The following is fast on Unix, but performance degrades
      # drastically on Windows beyond 4 workers.
 
      open my $MEM_FH, '<', $slurp_ref;
      binmode $MEM_FH, ':raw';
      while (<$MEM_FH>) { push @matches, $_ if (/$pattern/); }
      close   $MEM_FH;
 
      # Therefore, use the following construction on Windows.
 
      while ( $$slurp_ref =~ /([^\n]+\n)/mg ) {
         my $line = $1; # save $1 to not lose the value
         push @matches, $line if ($line =~ /$pattern/);
      }
 
      # Gather matched lines.
 
      MCE->gather(@matches);
   }
 
} $hugefile;
 
print join('', @result);