use strict;
use warnings;

use IO::Socket;

my $handle;
my $pid;
if (!defined($pid = open($handle, "|-"))) {
    die "Fork failed: ".$!;
}
elsif ($pid == 0) {
    # Child
    stdin->blocking(0);
    sleep(5);
    exit 0;
}
else {
    # Parent
    $handle->autoflush(1);
    $handle->blocking(0);
    my $i = 0;
    my $result;
    do {
        $result = print $handle "ABC\n";
        print "PIPE write  ".++$i."\n";
    } while ($i < 10000);
}