need to run long taking task in php - php

Question

In a commercial project I need to periodically monitor SMTP and Accounting servers to see if its running and working properly.
if its dead update a table in mysql.
I cant install any 3rd party app on server hosting php script or use exec or modify php settings through php_ini_set
each task takes about 10 to 30 seconds
I tried to run tasks through Jquery ajax calls
and it worked , but the problem is when the jquery request is running you cant navigate to any other page and xhr.abort(); is not working , and stucks on loading until jquery task finishes.
This is what i tried in my js file
var monitor_running = false;
var xhr;
function monitor() {
if (document.readyState === "complete") {
if (monitor_running === false) {
monitor_call();
}
else {
console.log("jobs Already running ===>");
}
}
}
window.onbeforeunload = function () {
console.log(xhr);
xhr.abort();
alert(xhr.status);
};
setInterval(monitor, monitor_interval * 1000);
function monitor_call() {
monitor_running = true;
console.log("jobs running");
xhr = $.ajax({url: './ajax.php',
data: {
cmd: 'monitor'
},
type: 'post',
async: true,
success: function (output) {
monitor_running = false;
console.log(output + " job is finished");
}
});
}
and in php page :
<?php
include_once '../includes/config.php';
$tpl_obj = new template('admin');
$navigation_obj = new navigation();
$auth = $navigation_obj->admin_is_auth();
if (!$auth) {
die('Auth Failed !');
}
function monitor() {
sleep(10);
echo 'done';
// $monReport['acc'] = monitor::domon('acc');
// $monReport['smtp'] = monitor::domon('smtp');
// $monReport['payment'] = monitor::domon('payment');
// $monReport['dns'] = monitor::domon('dns');
// return json_encode($monReport);
}
$cmd_post = filter_input(INPUT_POST, 'cmd');
$cmd_get = filter_input(INPUT_GET, 'cmd');
if ($cmd_post == 'monitor') {
echo monitor();
}