1.pm

#!/usr/bin/env perl

use strict;
use warnings;
use 5.8.8;

use IO::Handle;

use FindBin;
use Config;

my $Bin;
BEGIN {
    $ENV{DBIC_OVERWRITE_HELPER_METHODS_OK} = 1;

    unshift @INC, "$FindBin::Bin";
    unshift @INC, "$FindBin::Bin/lib";
    unshift @INC, "$FindBin::Bin/local/lib/perl5";
    unshift @INC, "$FindBin::Bin/local/lib/perl5/$Config{archname}";

    $ENV{LOAD_ROUTES} = 1;
}

use Parallel::ForkManager;
use Socket;
use DDP;

my $processes = 4;
my $pm = Parallel::ForkManager->new($processes);
my @files = ('a'..'z');

sub getFile {
    return shift @files;
}

my @children;
my @parents;

# Open each process
FILES:
foreach (0..$processes-1) {
    my $i = $_;
    socketpair($children[$i], $parents[$i], AF_UNIX, SOCK_STREAM, PF_UNSPEC);

    my $child = $children[$i];
    my $parent = $parents[$i];

    $child->autoflush(1);
    $parent->autoflush(1);

    $child->blocking(0);
    $parent->blocking(0);

    my $pid = $pm->start;

    if ($pid) { # parent
        # each child starts with a file;
        my $file = shift @files;
        chomp $file;
        if ($file) {
            print $child "$file\n";
        }
        while (<$child>) {
            my $file = shift @files;
            if (!$file) {
                last;
            }
            chomp $file;
            print $child "$file\n";
            sleep(1);
        }
        $parent->close();
        next FILES;
    }

    # children will start here
    while (<$parent>) {
        my $file = $_;
        chomp $file;
        
        print "child $i received $file\n";
        sleep(int(rand(2)));
        print $parent "2\n";
    }

    $child->close();

    $pm->finish;
}

$pm->wait_all_children;

print "done\n";