sub test_loop_4 {
  ####### Uses a lot less RAM, but still a lot, because there are 2mil elems in @all2...
  ####### A wild guess would be about 20-25*filesize in ramusage
  open(FILE, $file) or die $!;
  my $buf = '';
  my @all2 = ();
  while(read FILE,$buf,1) {
    push @all2,$buf;
  }
}