#!/usr/bin/env perl

use strict;
use warnings;

use Data::Dumper;
use Getopt::Long;
use Parallel::ForkManager;

$Data::Dumper::Deepcopy = 1;
$Data::Dumper::Sortkeys = 1;

$| = 1;

my $max_child = 5;

my %parent_hash = ();

my $pm = Parallel::ForkManager->new($max_child);
$pm->run_on_finish(
    sub {
        my ( $pid, $exit_code, $process_ident, $exit_signal,
            $core_dump, $ds_ref, )
          = @_;
        if ( defined $ds_ref ) {
            foreach my $k1 ( sort { $a cmp $b } keys %{$ds_ref} )
            {
                foreach my $k2 ( keys %{ $ds_ref->{$k1} } ) {
                    $parent_hash{$k1}{$k2} +=
                      $ds_ref->{$k1}{$k2};
                    $parent_hash{total}{$k2} +=
                      $ds_ref->{$k1}{$k2};
                }
            }
        }
    },
);

foreach ( my $i = 0 ; $i < 128 ; $i += 8 ) {
    $pm->start and next;

    sleep $i;

    srand();    # So children have different random seeds

    my $child_hash;
    foreach my $j ( 0 .. int( rand() * 5 + 1 ) ) {
        my $fn = sprintf qq{file%05d.dat}, $i + $j;
        my @letters = ( 'a' .. 'h', );
        foreach my $k ( 0 .. 3 ) {
            my $l;
            while ( $l = int( rand() * scalar @letters ) ) {
                last
                  unless (
                    exists $child_hash->{$fn}{ $letters[$l] } );
            }
            my $m = int( rand() * 20 );
            $child_hash->{$fn}{ $letters[$l] } = $m;
        }
    }
    print Data::Dumper->Dump(
        [ \$i, \$child_hash, ],
        [qw( *i *child_hash )]
      ),
      qq{\n};
    $pm->finish( 0, $child_hash, );
}
$pm->wait_all_children;

print Data::Dumper->Dump( [ \%parent_hash, ],
    [qw( *parent_hash )] ),
  qq{\n};