Parallel::ForkManager使って普通のforkっぽいことをやる

gistfile1.pl

use strict;
use warnings;

use IO::Handle;
use Parallel::ForkManager;

my $pm = Parallel::ForkManager->new(2);

my ($pread, $pwrite);
pipe $pread, $pwrite;
$pwrite->autoflush(1);

print time." parent $$\n";
if (!$pm->start) {
    close $pread;

    for (1..3) {
        print $pwrite time." write_child $$\n";
        sleep 1;
    }

    close $pwrite;
    print time." child finish $$\n";
    $pm->finish;
}
elsif (!$pm->start) {
    close $pwrite;
    while (<$pread>) {
        chomp;
        print time." read_child $$ '$_'\n";
    }
    sleep 3;
    print time." child finish $$\n";
    $pm->finish;
}
else {
    close $pread;
    close $pwrite;
    $pm->wait_all_children;
    print time." parent finish $$\n";
}