Run PHP script in background using GET request to avoid timeout - php

Question

I have a php script which downloads a CSV file and updates stock for products on PrestaShop.
The problem is that this script can be executed only through GET request but there is some timeout on the server-side which causes an error.
I can't increase the timeout so I have to figure out a workaround.
My idea is to make this script run the import snippet in the background (in another process) so the script will end almost immediately (eg. no timeout), but the import will run in the background.
Is it possible?
My script:
<?php
#ini_set('max_execution_time', 0);
include(dirname(__FILE__) . '/config/config.inc.php');
include(dirname(__FILE__) . '/init.php');
$url = 'URL';
$file_name = basename($url);
if(file_put_contents( $file_name,file_get_contents($url))) {
echo "File downloaded successfully";
}
else {
echo "File downloading failed.";
// die('error');
}
echo "\n";
echo "<br>";
$row = 1;
if (($handle = fopen($file_name, "r")) !== FALSE) {
while (($data = fgetcsv($handle, 1000, ";")) !== FALSE) {
$num = count($data);
$row++;
for ($c=0; $c < $num; $c++) {
// skip first ligne (header csv )
if ($row == 1 || $row == 2) {
continue;
}
if(!($data[5] == 'Suk' || $data[5] == 'plus size')){
continue;
}
// get attribut from prestashop database
if(empty($data[9]))
continue;
$productAttribut=findProductAttributByReference($data[9]);
// if product attribut exist
if(!empty($productAttribut)){
echo $productAttribut['id_product_attribute'];
// update quantity
StockAvailable::setQuantity((int)$productAttribut['id_product'],(int)$productAttribut['id_product_attribute'], (int)$data[10], Context::getContext()->shop->id);
echo "product ".$productAttribut['id_product_attribute']." quantity \n updated";
echo "\n";
echo "<br>";
}
}
}
fclose($handle);
echo "\n";
echo "<br>";
echo "end script ";
}
function findProductAttributByReference($reference){
$sql='
SELECT *
FROM `' . _DB_PREFIX_ . 'product_attribute`
WHERE `reference` = "' . $reference.'"'
;
$result = Db::getInstance()->getRow($sql);
return $result;
}
?>

Answer 1

No you can't,
As #martin Paucot said in comment, PHP is blocking. It will run all the instructions one by one. meanwhile, Each instruction will be waiting previous one to be finished.
So, Your main script will be waiting for your imported script to finish its execution.
Possible Way
Use CRON Job to export CSV in background and push a notification once it's job completed. So user will be notified once the job completed and download the file using a link. (You will need to store some records in database)