use Devel::Size qw[ total_size ];;
@a = 1 .. 1e6;;
print total_size( \@a );;
32000176

@a = ();;
print total_size( \@a );;
8000176

##</code><code>##

@a = 1 .. 1e6;;
print total_size( \@a );;
32000176

splice @a;;
print total_size( \@a );;
8000176

##</code><code>##

@a = 1 .. 1e6;;
print total_size( \@a );;
32000176

undef @a;;
print total_size( \@a );;
176