C:\test>215578 -BUFN=16 pipes.dat
1 trial of sysread (160.090s total)
1 trial of sysread2 (182.623s total)
1 trial of stdio (324.950s total)

sysread:20000 sysread2:20000 stdio:20000

##</code><code>##

#! perl -slw
use strict;
use Benchmark::Timer;
use vars qw[$BUFN];

$BUFN ||= 1; # Buffer size in steps of 4096 bytes.

my $t=Benchmark::Timer->new();
my $re_fields = qr[
	([^|]+)\| 			# Capture field 0
	(?:[^|]+\|){2}		# Skip 1 .. 2
	([^|]+)\|			# Capture 3 .. 4
	([^|]+)\|
	(?:[^|]+\|){4}		# Skip 5..8
	([^|]+)\|			# Capture 9
	(?:[^|]+\|){7}		# Skip 10..16
	([^|]+)\|			# Capture 17..18
	([^|]+)\|
	(?:[^|]+\|){11}     # Skip 19..30
	([^|\n]+)			# Capture 31
	\n					# Discard the newline
]ox;

my $buffer = "";

$t->start('sysread');
open my $in, $ARGV[0] or die "Couldn't open $ARGV[0]:$!";
my %h1;

while (sysread($in, $buffer, 4096*$BUFN, length $buffer)) {
	while($buffer =~ m[$re_fields]mog ) { # << Regex.
		$h1{$_}++ for ($1,$2,$3,$4,$5,$6,$7);
	}
	$buffer = substr($buffer, 1+rindex($buffer, "\n"));
}
close $in;

$t->stop('sysread');

$t->start('sysread2');
open $in, $ARGV[0] or die "Couldn't open $ARGV[0]:$!";
my %h2;

while (sysread($in, $buffer, 4096*$BUFN, length $buffer)) {
	my ($p1, $p2) = (0) x 2;
	while ($p2 = 1 + index($buffer, "\n", $p1)) {
		$h2{$_}++ for substr($buffer, $p1, $p2 - $p1) =~ $re_fields; # << Regex.
		$p1 = $p2;
	}
	$buffer = substr($buffer, 1+rindex($buffer, "\n"));
}
close $in;
$t->stop('sysread2');

my %h3;

$t->start('perlio');
open $in, $ARGV[0] or die "Couldn't open $ARGV[0]:$!";

while(<$in>){
	my @fields = split'[\|\n]';
	$h3{$_}++ for @fields[0,3,4,9,17,18,30];
}
close $in;
$t->stop('stdio');

$t->report;

print 'sysread:', scalar keys %h1, ' sysread2:', scalar keys %h2, ' stdio:', scalar keys %h3;

$h1{$_} ne $h3{$_} and print "$h1{$_} ne $h3{$_}" for keys %h3;
$h2{$_} ne $h3{$_} and print "$h2{$_} ne $h3{$_}" for keys %h3;
__END__
C:\test>215578 -BUFN=16 pipes.dat
1 trial of sysread (160.090s total)
1 trial of sysread2 (182.623s total)
1 trial of stdio (324.950s total)

sysread:20000 sysread2:20000 perlio:20000