This document discusses using cron queues in Drupal. Cron queues allow running long or recurring tasks asynchronously by adding items to a queue and processing them via cron. Key aspects covered include: - Adding items to a queue programmatically or via hooks and processing them via cron hooks or a queue worker callback - Modules that can be used to run cron queues like Ultimate Cron and Elysia Cron - Methods provided by the DrupalQueueInterface like createItem, claimItem, and releaseItem - Benefits of cron queues like decoupling tasks from cron runs and allowing only one job to run at a time

1. Introduction to Cron Queue
Olga Smolyankina

2. 300 FOR ALL

6. Run methods
cron.php
Ultimate Cron
Elysia Cron
.crontab
.crontab
drush queue-cron
modules/drupal_queue_cron.php

7. Usage cases
● Entity items creation.
● Sending emails.
● Other mass operations.

8. Usage cases

9. How To. Add Queue Items
$queue = DrupalQueue::get('queue_name');
$queue->createQueue();
$queue->createItem(array(
'key1' => $value1,
'key2' => $value2,
...
hook_cron()
)); API hook_node_insert($node)
hook_user_insert(&$edit, $account, $category)
hook_commerce_cart_order_empty($order)
...

10. How To. Add Queue Items
/**
* Implements hook_cronapi().
*/
function mymodule_queue_cronapi($op, $job = NULL) {
$items = array();
$items['add_queue_items'] = array(
'rule' => '0 5 * * *',
'arguments' => array(),
API
'callback' => 'add_queue_items_callback',
);
● Elysia Cron
return $items;
}

11. How To. Implementation
/**
* Implements hook_cron_queue_info().
*/
function mymodule_cron_queue_info() {
$queues = array();
$queues['queue_name'] = array(
'worker callback' => '_mymodule_queue_worker_callback',
'time' => 90,
'skip on cron' => FALSE,
);
return $queues;
}

12. How To. Process Queue Items
system.queue.inc
DrupalQueueInterface::createQueue();
DrupalQueueInterface::deleteQueue();
DrupalQueueInterface::createItem($data);
DrupalQueueInterface::claimItem($lease_time = 3600);
DrupalQueueInterface::releaseItem($item);
DrupalQueueInterface::deleteItem($item);
DrupalQueueInterface::numberOfItems();

13. Queue Run Tracking
● Queue UI
● Ultimate Cron

14. Negatives

15. Negatives vs Features
● Cron run frequency.
● Cron run duration.
● Cron run propriety.
● Item locking => single cron job at once.
● Queue decoupled from the code => external queue run!

16. Thank you!