My first reaction was that you must be using XML::Parser incorrectly. To test my assumption I created a 3.3MB XML file with 9000 elements containing random <message> elements. Then I created a regex script (regex.pl) and an XML::Parser script (parser.pl) which both pull out all the <message> contents. I ran them head to head and made sure they both produced the same output:

[sam@localhost xml_test]$ time ./parser.pl > parser.out
 
real    0m1.827s
user    0m1.730s
sys     0m0.040s

[sam@localhost xml_test]$ time ./regex.pl > regex.out
 
real    0m0.200s
user    0m0.160s
sys     0m0.040s

[sam@localhost xml_test]$ diff parser.out regex.out
[download]

So I'm seeing a simple regex beating a simple XML::Parser implementation by around 9x. Given that your regex takes three minutes, an XML::Parser script taking 35 minutes is within a similar multiple. When you consider that XML::Parser is making multiple Perl sub calls on each element it encounters, I guess it makes sense. But, still, ouch!.

Of course, if it were my job on the line I'd still use an XML parser. I've been bitten by changing specifications and funky data too many times to take the easy way out in the parser. In fact, these days I parse my XML twice - first with Xerces/C++ for schema validation and second with XML::Simple for actual usage. Better safe than sorry!

-sam

---

For the record, here's my test setup. First, the data generator:

#!/usr/bin/perl -w

print '<?xml version="1" encoding="UTF-8" ?>', "\n";
print "<test>\n";
for (0 .. 9000) {
    my $word = get_word();
    print "<$word>\n";
    if (rand(10) > 3) {
        for (0 .. rand(5)) {
            my $msg = get_words(30);
            print "\t<message>$msg</message>\n";
        }
    }
    print "</$word>\n";
}
print "</test>";

BEGIN {
    my @words;
    open(WORDS, "/usr/dict/words")
      or open(WORDS, "/usr/share/dict/words")
        or die "Can't open /usr/dict/words or /usr/share/dict/words: $
+!";
    while (<WORDS>) {
        chomp;
        push @words, $_ if /^\w+$/;
    }
    srand (time ^ $$);

    # get a random word
    sub get_word {
        return lc $words[int(rand(scalar(@words)))];
    }

    # get $num random words, joined by $sep, defaulting to " "
    sub get_words {
        my ($num, $sep) = @_;
        $sep = " " unless defined $sep and length $sep;
        return join($sep, map { get_word() } (0 .. ((int(rand($num)))+
+1)));
    }
}
[download]

The regex parser:

#!/usr/bin/perl -w

open(FILE, 'test.xml') or die $!;
my $xml = join('', <FILE>);

while($xml =~ m!<message>([\w\s]+)</message>!g) {
    print $1, "\n";
}
[download]

And the XML::Parser script:

#!/usr/bin/perl -w
use strict;
use XML::Parser;

my $p = new XML::Parser(Style => 'Stream', Pkg => 'main');
$p->parsefile('test.xml');

my $in_msg = 1;

sub StartTag { 
    $in_msg++ if $_ eq '<message>';
}

sub Text {
    print $_ if $in_msg;
}

sub EndTag {
    if ($_ eq '</message>') {
        $in_msg--;
        print "\n";
    }
}
[download]

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