my $i = 30000;
my %h = (new => {});
my $r = \%h;
for (0..$i) {
   print $_, "\r";
   $r = $r->{new};
   $r->{new} = {};
}
$r = $h{new};
undef %h;
while ($r) {
    $r = $r->{new};
}
print "end\n";