PHP Asynchronous Cron Job – Scheduling Tasks

In this tutorial I will provide a method to run cron jobs in PHP that too asynchronous without affecting page load time. This doesn’t require to install any PHP extension or any other kinds of coding horrors.

Logic

We need two PHP files. The first file checks if scheduled time has passed or just occurred for a cron job. If its time to run the task then it starts a new asynchronous process to run the second PHP which is actually the cron callback.

Complete Code

Files are named: cron.php and schedule.php. cron.php contains the callback code and schedule.php should be runned every time user makes a request to the web server.

Here is the code for schedule.php

<?php

if(get_option("cron_job_1") != null)
{
//run task every 1 hour.
if(time() - get_option("cron_job_1") >= 3600)
{
$ch = curl_init();

//send a request to the cron.php file so that its started in a new process asynchronous to the current process.
curl_setopt($ch, CURLOPT_URL, 'http://yourdomain/cron.php');
curl_setopt($ch, CURLOPT_FRESH_CONNECT, true);
//close connection after 1 millisecond. So that we can continue current script exection without effect page load time.
curl_setopt($ch, CURLOPT_TIMEOUT_MS, 1);
//some versions of curl don't support CURLOPT_TIMEOUT_MS so we have CURLOPT_TIMEOUT for them. Here we close connection after 1 second.
curl_setopt($ch, CURLOPT_TIMEOUT, 1);
curl_exec($ch);
curl_close($ch);

update_option("cron_job_1", time());
}
}
else
{
update_option("cron_job_1", time());
}

We have used PHP Options to store the last time in seconds when task was executed.

Here is the code for cron.php

<?php
// Ignore user aborts
ignore_user_abort(true);

//allow the script to run forever. this is optional depending on how heavy is the task
set_time_limit(0);

//put the task code here.

Dec 29, 2014Narayan Prusty

Comments: 8

olivedev

3 years ago

I tried to manually schedule a cron job for PHP script that was running on my site, but it was really difficult to do for a beginner like me. I have since used my hosting providers platform, Cloudways, to do it automatically, which was extremely easy (an example: https://www.cloudways.com/blog/schedule-cron-jobs-in-php/).

I wanted to ask if there is an easier way if I want to manually schedule tasks or using such platforms is the best alternative? Anyway thanks for this tutorial.

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Ketav

4 years ago

I’m geting this error :
Fatal error: Call to undefined function get_option() in /var/www/html/cron-job/schedule.php on line 4

I’m trying this demo with core php code.

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Mytaxe

4 years ago

its working fine

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Ramon Figueroa

4 years ago

What I have to do if I want to run this as my cron job.(see below) How I place this in your cron.php file. Thanks for your help.

0 * * * * /usr/bin/php /path/to/moodle/auth/db/cli/sync_users.php >dev/null

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Pradeep

4 years ago

Sorry i just included it.it’s fetching data but

i changed code as
set_time_limit(60);

//put the task code here. echo "hi pradeep";

$file = fopen(“bulk_upload.csv”,”r”);

while(! feof($file))
{
print_r(fgetcsv($file));
}

fclose($file);
?>

and my csv records as

1)pradeep varma Pradeep
pradeep.penumatcha@cognizant.com password

its displaying first record but i set time to 60 sec in between 60 sec i updated csv file added new record
2) rakesh raju rakesh rakesh@cognizant.com password

but after 60 sec its showing 1 record value only

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Pradeep

4 years ago

i written code as you mentioned above but it’s throughing

Fatal error: Call to undefined function get_option() in D:\xampp\htdocs\check\schedule.php on line 2

please help me..

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Narayan Prusty
4 years ago
Please read the tutorial carefully. I have mentioned to first use the code from
http://qnimate.com/storing-key-value-pairs-in-php-using-csv/
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