SMS not Sending to Customers from Observer.php - php

Question

I need to send SMS (By using any SMS API) to customers when products are back in stock.
I have rewrite Mage_ProductAlert_Model_Observer class and added SMS API in my Custom Module's Observer.php file but its not sending SMS to customers. Why?
Also, its only showing two customers details instead of all customers subscribed to product stock alert. Here is my code
Observer.php
<?php
class My_Alert_Model_ProductAlert_Observer
{
public function process()
{
$customer_stock_alerts = Mage::getModel('productalert/stock')
->getCollection()
->addStatusFilter(0)
->setCustomerOrder();
foreach ($customer_stock_alerts as $alert){
$stock_back_product = $alert->getProductId();
$current_product=Mage::getModel('catalog/product')->load($stock_back_product);
$current_product_name = $current_product->getName();
$customer_info = Mage::getModel('customer/customer')->load($alert->getCustomerId());
$customer_name = $customer_info->getPrimaryBillingAddress()->getFirstname();
$customer_mobile = $customer_info->getPrimaryBillingAddress()->getTelephone();
$message = 0;
$message = "Dear $customer_name, Product $current_product_name is back in Stock";
$message=urlencode($message);
$sendsms = "http://api.msg91.com/api/sendhttp.php?sender=MSGIND&route=4&mobiles=$customer_mobile&authkey=xxxxxxxxxxxxxxxxxxx&country=91&message=$message";
file_get_contents($sendsms);
}
}
}
?>
config.xml
<?xml version="1.0"?>
<config>
<modules>
<My_Alert>
<version>0.0.1</version>
</My_Alert>
</modules>
<global>
<models>
<my_alert>
<class>My_Alert_Model</class>
</my_alert>
</models>
</global>
<crontab>
<jobs>
<my_alert>
<schedule>
<cron_expr>*/5 * * * *</cron_expr>
</schedule>
<run>
<model>my_alert_productalert/observer::process</model>
</run>
</my_alert>
</jobs>
</crontab>
<frontend>
<routers>
<My_Alert_First>
<use>standard</use>
<args>
<module>My_Alert</module>
<frontName>my-alert</frontName>
</args>
</My_Alert_First>
</routers>
</frontend>
</config>
Can anyone share what's the issue this & why SMS is not sending?
I'm using Magento 1.9.

Answer 1

In Magento approach to handling Product Stock Alert collection. Our client has more than 40.000 subscribers and more than 30.000 are waiting for status to be changed from “Out of Stock” to “In Stock”. So when Magento tries to load 40.000 records from table product_alert_stock to collection to foreach them because of memory limitation php fails.
I Think you have not change core files you can over ride using your extension this link help you.