perl -e 'my %hash = map {$_=>$_} 1 .. 1_000; print "done"; sleep'
  perl -e 'my %hash = map {$_=>$_} 1 .. 10_000; print "done"; sleep'
  perl -e 'my %hash = map {$_=>$_} 1 .. 100_000; print "done"; sleep'