Preparation and Execution

I read the doco for XML::Simple again, paying special note of the sections 'SAX Support' and 'Environment'. I then downloaded a number of libraries and modules. Some come with perl, some with paricular OS vendors dists of perl. I recommend you scan your own system(s) to see what you may need.

• expat - C library for parsing XML - 1.95.7
• libxml2 - C library for parsing XML - 2.5.4
• XML::Parser - perl wrapper around expat - 2.34
• XML::LibXML - perl wrapper around libxml2 - 1.58
• XML::SAX - perl module that supplies or consumes SAX events - 0.12
• XML::SAX::Expat - backend for XML::SAX that uses the Expat library to supply SAX events - 0.37
• XML::LibXML::SAX - backend for XML::SAX that uses the libxml2 library to supply SAX events - 1.00
• XML::Simple - converts an XML document to a perl hash (roughly) - can have different backends drive this hash creation - 2.09

<plug mode="on">I wont go into using perl to do XML parsing, via the SAX and DOM paradigms - if you want to know more, come to my talk on this at OSDC conference.</plug>

Also, I used the following code - note it isn't like most benchmark code you see in the monastery - for a start it doesnt 'use Benchmark;'. This wasnt necessary as we are messuring an operation that takes 10's of seconds, not micro- and milli- seconds. The differences in speed standout without the help of the Benchmark module.
This code is pretty ugly too, but I believe it doesnt need a lot of trimming/reshaping. I was careful to make sure the measurements are tightly wrapped around the method/function calls, so as not to artificially inflate durations.

#!/usr/bin/perl -w

use strict;

use XML::Simple qw(:strict);
use Time::HiRes qw(time);
use File::stat;
use Test::More qw(no_plan);

my $xs;
my $XMLFile = $ARGV[0];
my $size = stat($XMLFile)->size();
print "File $XMLFile is " . $size . " bytes\n";

my ($start, $end);

$xs = XML::Simple->new(ForceArray => 0,
               KeyAttr    => {});

my $backend = '';
my $xml_default;
{
    local $ENV{XML_SIMPLE_PREFERRED_PARSER} = $backend;

    $start = time();
    $xml_default = $xs->XMLin($XMLFile);
    $end = time();
}

print_result($backend, $end, $start, $size);

$backend = 'XML::Parser';
my $xml_x_p;
{
    local $ENV{XML_SIMPLE_PREFERRED_PARSER} = $backend;

    $start = time();
    $xml_x_p = $xs->XMLin($XMLFile);
    $end = time();
}

print_result($backend, $end, $start, $size);

$backend = 'XML::SAX::Expat';
my $xml_x_s_e;
{
    local $ENV{XML_SIMPLE_PREFERRED_PARSER} = $backend;

    $start = time();
    $xml_x_s_e = $xs->XMLin($XMLFile);
    $end = time();
}

print_result($backend, $end, $start, $size);

$backend = 'XML::LibXML::SAX';
my $xml_x_l_s;
{
    local $ENV{XML_SIMPLE_PREFERRED_PARSER} = 'XML::LibXML::SAX';

    $start = time();
    $xml_x_l_s = $xs->XMLin($XMLFile);
    $end = time();
}

print_result($backend, $end, $start, $size);

is_deeply($xml_default, $xml_x_p);
is_deeply($xml_default, $xml_x_s_e);
is_deeply($xml_default, $xml_x_l_s);

sub print_result {
    my ($backend, $end, $start, $size) = @_;

    my $duration = $end - $start;

    print "XML::Simple with $backend backend took ", sprintf("%02.4f",
+ $duration), " seconds. ";

    print "This equates to ", sprintf("%02.4f", $size / ($duration)), 
+" kilobytes per second (1024 bytes per k)\n";
}
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