Debug Mage_Index_Model_Event stock related memory problem during checkout

Question

This project has around 150k skus with stock management enabled, most of them are configurable products... We've been live with 256Mb php memory_limit, but during last weeks we're having allowed memory errors during checkout

Errors come when last available unit of a configurable child is sold (stock status change)

We've fixed this raising memory_limit to 512Mb, but I'd like to see which data is consuming so much memory, the concrete piece of code firing the error is the setNewData() line in mergePreviousData() method, in Mage_Index_Model_Event class

public function mergePreviousData($data)
{
    if (!empty($data['event_id'])) {
        $this->setId($data['event_id']);
        $this->setCreatedAt($data['created_at']);
    }

    if (!empty($data['new_data'])) {
        $previousNewData = unserialize($data['new_data']);
        $currentNewData  = $this->getNewData(false);
        $currentNewData = $this->_mergeNewDataRecursive($previousNewData, $currentNewData);
        $this->setNewData(serialize($currentNewData));
    }
    return $this;
}

I've checked $currentNewData in DB, and it is a very simple and light object, with just some properties... so I suspect problem must be with that _mergeNewDataRecursive() previous line, but I am not sure which part of the checkout request is consuming so much memory

Any ideas?

Answer 1

Honestly, it's hard to guess which line consumes the most memory.

I suggest you use the profile to find out exactly which line is the culprit.

First enable the profiler.

Then update the code with the following:

public function mergePreviousData($data)
{
    if (!empty($data['event_id'])) {
        $this->setId($data['event_id']);
        $this->setCreatedAt($data['created_at']);
    }

    if (!empty($data['new_data'])) {
        Varien_Profiler::start('unserialize');
        $previousNewData = unserialize($data['new_data']);
        Varien_Profiler::stop('unserialize');
        Varien_Profiler::start('getNewData');
        $currentNewData  = $this->getNewData(false);
        Varien_Profiler::stop('getNewData');
        Varien_Profiler::start('_mergeNewDataRecursive');
        $currentNewData = $this->_mergeNewDataRecursive($previousNewData, $currentNewData);
        Varien_Profiler::stop('_mergeNewDataRecursive');
        Varien_Profiler::start('setNewData');
        $this->setNewData(serialize($currentNewData));
        Varien_Profiler::stop('setNewData');
    }
    return $this;
}

Trigger this code (according to your question by selling the last available unit of a configurable child) and check the results.

I know this is not a fix but when you deal with a lot of skus and when you're not on EE, those memory issues are hard to track down.