#!perl -w
use strict;
$|=1;
my (%a,%b,%c);
for (0 .. 500_000) { # set higher if you dare
    $a{$_} = "x" x 60; # 60 character string
    $b{$_} = "x" x 60;
    $c{$_} = "x" x 60;
    print "\rrow $_" unless $_ % 10000;
}
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note: this goes up to 190 mb for about 500_000 iterations on my machine YMMV.