use Parallel::ForkManager;

  $pm = new Parallel::ForkManager(100);
  my @all_data = qw/1/;
  foreach $data (@all_data) {
    # Forks and returns the pid for the child:
    my $pid = $pm->start; 
    print "PID $pid\n";
    $pid and next;
    print "$data", "\n";

    my $pid2 = fork();
    unless ($pid2) {
      exec $^X, '-e', 'while(){}';
    }
    print "Real PID $pid2\n";
    waitpid $pid2, 0;


    $pm->finish; # Terminates the child process
  }
 $pm->wait_all_children;

##</code><code>##

exec $^X, '-e', 'while(){}';

##</code><code>##

exec "perl -e 'while(){}'";