$ perl -le '$x=2**30; print $x; $a[$x]=0'
1073741824
Out of memory during array extend at -e line 1.

##</code><code>##

@lines = <FILE>;        # copy 1
$all = join("",@lines); # copy 2
for (@lines) {
    ($key,$val) = split " ", $_, 2;
    $hash{$key} = $val;   # copy 3
}