'Out of memory!' Error with XML::Simple

silent11 has asked for the wisdom of the Perl Monks concerning the following question:

Surely I'm doing something wrong here! There is now way a 27 line XML file can bring XML::Simple to it's knees.

When I run this code:

use strict;
use warnings;
use XML::Simple;

my $associate = XMLin('./amazon.xml', forcearray=>0);

my $books = $associate->{books}->{item};
my $cds = $associate->{cds}->{item};
my $dvds = $associate->{dvds}->{item};
my $wish = $associate->{ wish}->{item};

foreach my $books (values %$books) {
    print "$books->{'asin'} \n";
    }
[download]

I get this error: Out of memory!

Here is my XML file:

<associate>
    <books>
        <item item_name="Mysql and Perl for the Web" asin="0735710546"
+ />
        <item item_name="Macromedia Flash MX: Training from the Source
+" asin="0201794829" />
        <item item_name="XSLT" asin="0596000537" />
        <item item_name="Learning XML" asin="0596000464" />
        <item item_name="Programming Perl (3rd Edition)" asin="0596000
+278" />
        <item item_name="Network Programming with Perl" asin="02016157
+11" />
        <item item_name="Cisco Networking Academy Program: Fundamental
+s of UNIX Companion Guide" asin="1587130440" />
    </books>
    <dvds>
        <item item_name="Gladiator (2000)" asin="B00003CXE7" />
        <item item_name="The Princess Bride (Special Edition) (1987)" 
+asin="B00005LOKQ" />
        <item item_name="Pi" asin="078401213X" />                
    </dvds>
    <cds>
        <item item_name="OK Computer (Radiohead)" asin="B000002UJQ" />
        <item item_name="Pablo Honey (Radiohead)" asin="B000002UR7" />
        <item item_name="Parachutes (Coldplay)" asin="B0000508U6" />
        <item item_name="Hatful of Hollow (The Smiths)" asin="B000002M
+IF" />        
    </cds>
    <wish>
        <item item_name="The Usual Suspects (Special Edition) (1995)" 
+asin="B00005V9HH" />
        <item item_name="How to Win Friends and Influence People" asin
+="0671723650" />
        <item item_name="ActionScript for Flash MX: The Definitive Gui
+de, Second Edition " asin="059600396X" />
    </wish>
</associate>
[download]

Windows 2000
perl 5.6.1
XML::Simple 1.06

-Silent11

Comment on 'Out of memory!' Error with XML::Simple Select or Download Code

Replies are listed 'Best First'.
Re: 'Out of memory!' Error with XML::Simple by gjb (Vicar) on Jan 14, 2003 at 22:18 UTC
I don't know why such an amount of memory is used (I can only assume XML::Simple gets very confused), but I do know how to deal with it. Using Data::Dumper I noticed that `$books` is not a hashref, but a listref. Replacing the `foreach` with: `foreach my $book (@$books) { print "$book->{'asin'} \n"; }` [download] solves the problem. Hope this helps, -gjb-	[reply] [d/l] [select]
Re: 'Out of memory!' Error with XML::Simple by grantm (Parson) on Jan 14, 2003 at 23:32 UTC
This is covered in the XML::Simple FAQ. The cause of the problem is that you're treating an arrayref as if it was a hashref (as gjb pointed out). There are a few more things worthy of consideration and I'd recommend you take a look at Does your XML::Simple code pass the strict test? for more complete coverage. But in brief: you are not setting a value for the keyattr option (if you don't know what it does, set `keyattr => []`) you are turning off forcearray which is a bad idea for two reasons: your code will break if you only have one <item> enabling array folding (which you're doing by letting keyattr default) is inherently incompatible with disabling forcearray your <item> elements have an 'item_name' attribute where 'name' might be a more natural choice - I'm guessing you tried using name but "weird stuff happened" (because you didn't set keyattr to disable array folding) The 'strict mode' link above has more detail.	[reply] [d/l]
Re: 'Out of memory!' Error with XML::Simple by traveler (Parson) on Jan 14, 2003 at 22:26 UTC
gjb hit the nail on the head. Put a call to exit before the loop and it does not run out of memory. The issue is the loop. The fixes gjb suggested do the job. --traveler	[reply]