use 5.010;
use strict;
use warnings;

use Symbol qw/gensym/;

sub spawn_worker(&) {
  my ($thunk) = @_;
  
  my $pipe = gensym;
  my $pid = open $pipe, '-|';
  die "Unable to create worker: $!" unless (defined($pid));
  
  if ($pid == 0) {
    $thunk->($pipe);
    exit 0;
  }
  else {
    return ($pid, $pipe);
  }
}

sub collect_work($*) {
  my ($pid, $pipe) = @_;
  my $_;
  
  print "$pid >> $_" while (<$pipe>);
  die "Unable to read from worker $pid: $!" if ($!);
  
  close $pipe or die "Unable to close worker $pid: $!";
}

my %workers = ();
for my $idx (0..10) {
  my ($pid, $pipe) = spawn_worker {
    print "Hello, I'm worker $idx\n";
  };
  
  $workers{$pid} = $pipe;
}

while (my ($pid, $pipe) = each %workers) {
  collect_work $pid, $pipe;
}