use strict;
use warnings;
use Benchmark 'cmpthese';

my %subs = (
            list_io =>
            sub {
        		# Second time round this will take
        		# a loooooong time.
				my $file=$0;
				my @line;
				open my($fh), $file;
				@line= <$fh>;
				close($fh);
				return \@line;
			},

			split_slurp =>
			sub {
				my $file=$0;
				my @line;
				local $/;
			  	open my($fh), $file;
				@line=split /\n/,<$fh>;
				close($fh);
				return \@line;
			},

            while_io =>
            sub {
				my $file=$0;
				my @line;
			 	open my($fh), $file;
			 	push @line,$_ while <$fh>;
				close($fh);
				return \@line;
			},
          );

cmpthese -5,\%subs;

__END__

##</code><code>##

Benchmark: running list_io, split_slurp, while_io, each for at least 5 CPU seconds...
   list_io:  5 wallclock secs ( 3.89 usr +  1.34 sys =  5.24 CPU) @ 1721.98/s (n=9018)
split_slurp:  4 wallclock secs ( 3.02 usr +  2.21 sys =  5.23 CPU) @ 2725.38/s (n=14251)
  while_io:  7 wallclock secs ( 3.64 usr +  1.38 sys =  5.02 CPU) @ 1629.26/s (n=8174)
              Rate    while_io     list_io split_slurp
while_io    1629/s          --         -5%        -40%
list_io     1722/s          6%          --        -37%
split_slurp 2725/s         67%         58%          --