Magento foreach() orders getAllItems() - magento

Question

I am not sure why this loop is not working.
$orders = Mage::getSingleton('sales/order')->getCollection()
->addAttributeToSelect('*')
->addFieldToFilter('created_at', array('from'=>$from, 'to'=>$to))
->addAttributeToSort('increment_id', 'ASC')
;
foreach ($orders as $item) {
$order_id = $item->increment_id;
if (is_numeric($order_id)) $order = Mage::getModel('sales/order')->loadByIncrementId($order_id);
if (is_object($order)) {
echo "> O: ". $order_id ."<BR>";
$items = $order->getAllItems();
echo ">> O: ". $order_id ."<BR>";
} else
die("DIE ". var_dump($order));
}
die("<BR> DONE");
The output:
...
...
>> O: 100021819
> O: 100021820
>> O: 100021820
> O: 100021821
The loop never finishes nor does it stop at the same order_id.?
It always fails at $order->getAllItems()
These orders are either pending, processing or complete.
Is there something I should be checking for with $order->getAllItems(), since that's were it's failing.
Thanks.

Answer 1

Jon, I assume the problem you're talking about is your script ending un expectedly. i.e., you see the output with a single >
> O: 100021821
but not the output with the double >>.
Because Magento is so customizable, it's impossible to accurately diagnose your problem with the information given. Something is happening in your system, (a PHP error, an uncaught exception, etc.), that results in your script stopping. Turn on developer mode and set the PHP ini display_errors to 1 (ini_set('display_errors', 1);) and check your error log. One you (or we) have the PHP error, it'll be a lot easier to help you.
My guess is you're running into a memory problem. The way PHP has implemented objects can lead to small memory leaks — objects don't clean up after themselves correctly. This means each time you go through the loop you're slowly consuming the total amount of memory that's allowed for a PHP request. For a system with a significant number of orders, I'd be surprised if the above code could get through everything before running out of memory.
If your problem is a memory problem, there's information on manually cleaning up after PHP's objects in this PDF. You should also consider splitting your actions into multiple requests. i.e. The first request handles orders 1 - 100, the next 101 - 200, etc.

Answer 2

What do you mean it fails?
By the look of the output it doesn't fail there as it outputs text either side of the call to getAllItems()
change:
$items = $order->getAllItems();
to:
foreach($order->getAllItems() as $orderItem) {
echo $orderItem->getId() . "<br />";
}
and see what happens.
The script could be ending on a different order ID each time if you have a low memory limit set on the server and it quits when it runs out of resources.