ev memory leak

#!/usr/bin/perl

use v5.14;
use EV;
use AnyEvent;
use AnyEvent::Handle;

my $cv = AnyEvent->condvar;

my $i = 0;
my $io;

sub get_next {
    say localtime.": allocatating new 1 000 000 chars";
    my $big_data = 'A' x 1_000_000;
    sleep 1;

    return $big_data;
};

open my $dev_null, '>', '/dev/null';

my $io = AnyEvent::Handle->new(fh => $dev_null, on_drain => sub {
    my ($io) = @_;
    say localtime.": @{[ $i++ * 1_000_000 ]} bytes already written";

    my $big_data = get_next();

    say localtime.": async write to /dev/null allocated content";
    $io->push_write($big_data);
    undef $big_data;

    say localtime.": exiting context";
});

$cv->recv();