I don't think this is the complete answer as
read $IN1, my $buffer, -s $IN1;
++$counts{$_} for split( /^/m, $buffer );
is faster than the
for.
/dev/null
Rate for read while
for 362612/s -- -7% -19%
read 389496/s 7% -- -13%
while 449755/s 24% 15% --
/usr/share/dict/words
Rate for read while
for 4.73/s -- -17% -37%
read 5.73/s 21% -- -24%
while 7.55/s 60% 32% --
/etc/passwd
Rate for while read
for 14434/s -- -17% -21%
while 17297/s 20% -- -6%
read 18355/s 27% 6% --
#!/usr/bin/perl
use strict;
use Benchmark qw( cmpthese );
foreach my $file qw ( /dev/null /usr/share/dict/words /etc/passwd ) {
open my $IN1, '<', $file or die "could not open $file";
my @list = <$IN1>;
seek( $IN1, 0, 0 );
print "$file\n";
cmpthese(
-5,
{
for => sub {
seek( $IN1, 0, 0 );
my %counts = ();
++$counts{$_} for <$IN1>;
die unless keys %counts == @list;
},
while => sub {
seek( $IN1, 0, 0 );
my %counts = ();
++$counts{$_} while <$IN1>;
die unless keys %counts == @list;
},
read => sub {
seek( $IN1, 0, 0 );
my %counts = ();
read $IN1, my $buffer, -s $IN1;
++$counts{$_} for split( /^/m, $buffer );
die unless keys %counts == @list;
},
}
);
}
-- gam3
A picture is worth a thousand words, but takes 200K.