Magento - memory error trying to get thumbnail

Edit: I'm using Magento 1.6.2 (community)

I want to iterate over products. I run the following code (althought this is not a full file, it is part of a SOAP service's class definition - methods not described here are not important to my issue):

//ok private function _listProductData($product, $full = false) { $result = array( //_getProductAttribute($product, $attribute) 'product_id' => $product->getId(), 'type' => $product->getTypeId(), 'position' => $product->getCatIndexPosition(), 'sku' => $product->getSku(), 'price' => $this->_getProductAttribute($product, 'price'), 'kilometraje' => $this->_getProductAttribute($product, 'kilometraje'), 'thumbnail' => Mage::helper('catalog/image')->init($product, 'thumbnail'), 'model' => $this->_getProductModel($product) ); if ($full) { //meter mas datos $result = $result + array( 'image' => $this->_getProductAttribute($product, 'small_image'), 'tipo_vehiculo' => $this->_getProductAttribute($product, 'vehiculo_tipo', true), 'cilindrada' => $this->_getProductAttribute($product, 'cilindrada', true), 'combustible' => $this->_getProductAttribute($product, 'combustible', true), 'transmision' => $this->_getProductAttribute($product, 'transmision', true), 'direccion' => $this->_getProductAttribute($product, 'direccion', true), 'traccion' => $this->_getProductAttribute($product, 'traccion', true), 'anio' => $this->_getProductAttribute($product, 'rango_anio', true), 'tapiz' => $this->_getProductAttribute($product, 'tapiz', true), 'aire_acondicionado' => $this->_getProductAttribute($product, 'aire_acondicionado', true), 'vidrios' => $this->_getProductAttribute($product, 'vidrios', true), 'origen' => $this->_getProductAttribute($product, 'origen', true), 'numero_placa' => $this->_getProductAttribute($product, 'numero_placa', true), 'placa' => $this->_getProductAttribute($product, 'placa') ); } //$result = array(); //foreach ($product->getTypeInstance(true)->getEditableAttributes($product) as $attribute) { // if ($this->_isAllowedAttribute($attribute, $attributes)) { // $result[$attribute->getAttributeCode()] = $product->getData($attribute->getAttributeCode()); // } //} return $result; } //ok private function _listProductCollection($collection, $offset, $order) { //ordenamos y nos quedamos con un cachito de la coleccion nomas $order = in_array($order, array('ASC', 'DESC', false)) ? $order : false; $order ? $collection->setOrder('name', $order) : false; $collection->setPage($offset, 10); //iteramos y recolectamos los datos (TO-DO listar los atributos y la imagen principal) $result = array(); foreach ($collection as $product) { $result[] = $this->_listProductData($product, false); } return $result; } //ok public function listVehicles($categoryId=null, $offset=1, $order='ASC') { $categoryId = (int) $categoryId; $offset = (int) $offset; if (($categoryId < 1) || ($offset < 1) || !in_array($order, array('DESC', 'ASC'))) { $this->_fault('bad_params'); } //cargamos categoria actual, y store actual (1). //la categoria no puede ser de una rama que no sea Marcas o Tipos. //si eso pasa, o la categoria no existe, tiramos un 404. $category = $this->_initCategory($categoryId, 1); $parentId = $category->getParentId(); if (!in_array($parentId, array(4, 94))) { $this->_fault('category_not_exists'); } //tratamos su lista de resultado. return $this->_listProductCollection($category->setStoreId($storeId = 1)->getProductCollection()->addAttributeToSelect('*'), $offset, $order); } 

To get the images of each individual item, I used to let the line $this->_getProductAttribute($product, 'thumbnail'), but it returned a relative url like: /p/c/pcd0748-1.jpg (url only illustrative).

When I tried to get the full url, by knowing its base url so I only have to append the chunk, I found such base url is not so "stable" (i.e. is not a well-known folder structure, but something related to cache):

http://www.blablabla.com/media/catalog/product/cache/1/small_image/201x201/17f82f742ffe127f42dca9de82fb58b1/p/c/pcd0748-1.jpg

So I cannot simply take that long url as base url because of the hash - the common sense tells us that this base url will change.

So I changed the image retrieval line to the currently given (Mage::helper('catalog/image')->init($product, 'thumbnail')) and I'm getting a memory error (I get a subset of 10 products, so such line is run 10 times in total).

Fatal error: Allowed memory size of 314572800 bytes exhausted (tried to allocate 295698398 bytes) ... (¡¡¡295MB for 10 images!!!)

Is there a more performant way that doesn't kill my memory for 10 images? I know such images exist, and just want to get the image urls.