my $total_children = 1000;
my @job_list = 1..$total_children;
my $max_children   = 100;
my $job_size       = 10;

my $main_pfm = P::FM->new( int($max_children/$job_size) );

my $sleep_time;

while ( my @batch = splice(@job_list, 0, $job_size) ) {

  $sleep_time++;
  $main_pfm->start and next;

  run_job( @batch );

  $main_pfm->finish;
}

sub run_job {
  my @jobs = @_;

  my $job_pfm = P::FM->new( scalar(@jobs) );

  foreach ( @jobs ) {
    $job_pfm->start and next;

    print "Starting job $_\n";
    sleep $sleep_time;

    $job_pfm->finish;
  }
}