my $total_children = 1000;
my $max_children   = 100;
my $job_size       = 10;
my $main_pfm = P::FM->new( $max_children/$job_size );

foreach ( 1..$total_children/$job_size ) {
  $main_pfm->start and next;
  run_job( $job_size );
  $main_pfm->finish;
}

sub run_job {
  my $job_size = shift;
  my $job_pfm = P::FM->new( $job_size );

  foreach ( 1..$job_size ) {
    $job_pfm->start and next;
    sleep $_;
    $job_pfm->finish;
  }
}