Memory leak in php

Fatal error: Out of memory (allocated 1846542336) (tried to allocate 65488 bytes) in C:\xampp\htdocs\zephineshop\inc\products.php on line 39

<?php

function get_connection() {
    try {
        $db = new PDO("mysql:host=" . DB_HOST . ";dbname=" . DB_NAME .";port=" . DB_PORT,DB_USER,DB_PASS);
        $db->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
        $db->exec("SET NAMES 'utf8'");
        return $db;
    } catch (Exception $e) {
        echo "Could not connect to the database.";
        exit;
    }
}

function return_all() {
    try {
        $db = get_connection();
        $results = $db->query("SELECT * FROM products ORDER BY sku;");
        $products = $results->fetchAll(PDO::FETCH_ASSOC);
    } catch (Exception $e) {
        echo "Data could not be retrieved from the database.";
        exit;
    }
    return $products;
}

function return_by_sku($sku) {
    try {
        $db = get_connection();
        $result = $db->prepare("SELECT * FROM products WHERE sku = ?;");
        $result->bindParam(1, $sku);
        $result->execute();
        $product = $result->fetch(PDO::FETCH_ASSOC);
    } catch (Exception $e) {
        echo "Data could not be retrieved from the database.";
        exit;
    }
    return $product;
}

function return_subset($start, $end) {
    try {
        $db = get_connection();
        $results = $db->prepare("SELECT * FROM products
            ORDER BY sku LIMIT ?, ?;");
        $results->bindParam(1, $start);
        $results->bindParam(2, $end);
        $results->execute();
        $products =  $results->fetchAll(PDO::FETCH_ASSOC);
    } catch (Exception $e) {
        echo "Data could not be retrieved from the database.";
        exit;
    }
    return $products;
}

function total_count() {
    try {
        $db = get_connection();
        $count = $db->query("select count(*) from products;");
        $total = $count->fetch(PDO::FETCH_ASSOC);
    } catch (Exception $e) {
        echo "Data could not be retrieved from the database.";
        exit;
    }
    return intval($total);
}

function return_sizes_by_sku($sku) {
    $sizes = array();
    try {
        $db = get_connection();
        $result = $db->prepare("SELECT s.size FROM products as p
            inner join products_sizes as ps on p.sku = ps.product_sku
            inner join sizes as s on ps.size_id = s.id WHERE p.sku = ?
            order by s.order;");
        $result->bindParam(1, $sku);
        $result->execute();

        while($i = $result->fetch(PDO::FETCH_ASSOC)){
            $sizes[] = $i['size'];
        }
    } catch (Exception $e) {
        echo "Data could not be retrieved from the database.";
        exit;
    }
    return $sizes;
}

<?php

require_once(ROOT_PATH . "inc/database.php");

/*
 * Loops through all the products, looking for a search term in the product names
 * @param    string    $s    the search term
 * @return   array           a list of the products that contain the search term in their name
 */
function get_products_search($s) {
    $results = array();
    $all = get_products_all();

    foreach($all as $product) {
        if (stripos($product["name"],$s) !== false) {
            $results[] = $product;
        }
    }
    return $results;
}

/*
 * Counts the total number of products
 * @return   int             the total number of products
 */
function get_products_count() {
    return total_count();
}

/*
 * Returns a specified subset of products, based on the values received,
 * using the order of the elements in the array .
 * @param    int             the position of the first product in the requested subset 
 * @param    int             the position of the last product in the requested subset 
 * @return   array           the list of products that correspond to the start and end positions
 */

function get_products_subset($positionStart, $positionEnd) {
    $subset = get_products_subset($positionStart, $positionEnd);
    return $subset;
}

/*
 * Returns an array of product information matching the sku
 * @param    int      $sku       the sku of the product
 * @return      mixed   array   list of products information for matching product
 */

function get_single_product($sku) {
    $product = return_by_sku($sku);
    $sizes = return_sizes_by_sku($sku);
    $product['sizes'] = array();
    foreach ($sizes as $size) $product['sizes'][] = $size;
    return $product;
}

/*
 * Returns the full list of products. This function contains the full list of products,
 * and the other model functions first call this function.
 * @return   array           the full list of products
 */
function get_products_all() {
    $products = return_all();
    return $products;
}