this might not be exactly what you want, but if the goal is to evaluate the progress of the operation, you could maybe look at Term::ProgressBar. I've not personally used it but have kind of kept in mind for the future. Basically, you set up the object with the total number of items to process and then update it throughout the processing and it will show you how much has been completed as well as an estimate of when it will be completed.

Here's an example straight out of the perldocs for those who don't want to click through to the above:

#!/usr/bin/perl

  use Term::ProgressBar 2.00;

  use constant MAX => 100_000;

  my $progress = Term::ProgressBar->new(MAX);

  for (0..MAX) {
    my $is_power = 0;
    for(my $i = 0; 2**$i <= $_; $i++) {
      $is_power = 1
        if 2**$i == $_;
    }

    if ( $is_power ) {
      $progress->update($_);
    }
  }
[download]

Anyway, maybe not exactly the solution you were looking for but it's something I've been meaning to use and thought it might come in handy for your case.