Time complexity of _loadAttributes in Eav\Model\Entity\Collection\AbstractCollection increases with number of products in cart and attributes

[senthilengg]

Preconditions and environment

Magento 2.4.x

Steps to reproduce

1. Review https://github.com/magento/magento2/blob/2.4-develop/app/code/Magento/Catalog/Model/AbstractModel.php#L180 and there is a nested for in https://github.com/magento/magento2/blob/2.4-develop/app/code/Magento/Eav/Model/Entity/Collection/AbstractCollection.php#L1236 and it calls _setItemAttributeValue once per attribute and _setItemAttributeValue iterates all products and set the value which is O(n*m) [50 products in cart & 50 attributes leads to 2500 iterations]

n = number of attributes
m= numbers of products

Profiler Output

2. In addition setData function in https://github.com/magento/magento2/blob/2.4-develop/app/code/Magento/Catalog/Model/AbstractModel.php#L180 does the same validation for all products instead it should be done once per attribute per collection given it doesn't change per product or per entityValue

Expected result

Iterates the number of rows from select query and then set once per product

Actual result

Iterates per attribute per product which increases the time complexity to multifold

Additional information

Proposal is to avoid the nested loop with the below

In Magento\Eav\Model\Entity\Collection\AbstractCollection::_loadAttributes

Replace

foreach ($values as $value) {
    $this->_setItemAttributeValue($value);
}

With

$attributeCode = $data = [];
$entityIdField = $this->getEntity()->getEntityIdField();

foreach ($values as $value) {
   $entityId = $value[$entityIdField];
    $attributeId = $value['attribute_id'];
    if(!isset($attributeCode[$attributeId])) {
        $attributeCode[$attributeId] = array_search($attributeId, $this->_selectAttributes);
        if (!$attributeCode[$attributeId]) {
            $attribute = $this->_eavConfig->getAttribute(
                $this->getEntity()->getType(),
                $attributeId
            );
            $attributeCode[$attributeId] = $attribute->getAttributeCode();
        }
        $data[$entityId][$attributeCode[$attributeId]] = $value['value'];
    }
}
if($data)
    $this->_setItemAttributeValue($data);

Replace Magento\Eav\Model\Entity\Collection\AbstractCollection::_setItemAttributeValue with the below

protected function _setItemAttributeValue($valueInfo)
    {
       foreach ($valueInfo as $entityId => $value) {
            if (!isset($this->_itemsById[$entityId])) {
                throw new LocalizedException(
                    __('A header row is missing for an attribute. Verify the header row and try again.')
                );
            }
           $object =$this->_itemsById[$entityId][0];
           $value = array_replace($object->getData(), $value);
           $object->setData($value);
        }
        return $this;
    }

Thus avoid calling _setItemAttributeValue equivalent to the number of attributes and internally it calls all products per attribute

Additional Questions

Since array_replace is memory intensive for large array would it benefit over all or not ?

Triage and priority

• Severity: S0 - Affects critical data or functionality and leaves users without workaround.
• Severity: S1 - Affects critical data or functionality and forces users to employ a workaround.
• Severity: S2 - Affects non-critical data or functionality and forces users to employ a workaround.
• Severity: S3 - Affects non-critical data or functionality and does not force users to employ a workaround.
• Severity: S4 - Affects aesthetics, professional look and feel, “quality” or “usability”.

[m2-assistant]

Hi @senthilengg. Thank you for your report.
To speed up processing of this issue, make sure that the issue is reproducible on the vanilla Magento instance following Steps to reproduce.

• For more details, review the Magento Contributor Assistant documentation.
• Add a comment to assign the issue: @magento I am working on this
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