How to delete scheduled task?

How can I ensure that each WP Cron scheduled task is completed?

• I'm planning to create a plugin that modifies posts in the background using WP Cron and a large number of tasks will be scheduled. As I look into the wp-cron.php file, cron tasks are performed in a loop. foreach ( $crons as $timestamp => $cronhooks ) { if ( $timestamp > $gmt_time ) break; foreach ( $cronhooks as $hook => $keys ) { foreach ( $keys as $k => $v ) { $schedule = $v['schedule']; if ( $schedule != false ) { $new_args = array($timestamp, $schedule, $hook, $v['args']); call_user_func_array('wp_reschedule_event', $new_args); } wp_unschedule_event( $timestamp, $hook, $v['args'] ); /** * Fires scheduled events. * * @since 2.1.0 * * @param string $hook Name of the hook that was scheduled to be fired. * @param array $v['args'] The arguments to be passed to the hook. */ do_action_ref_array( $hook, $v['args'] ); // If the hook ran too long and another cron process stole the lock, quit. if ( _get_cron_lock() != $doing_wp_cron ) return; } } } Say I have 1000 separate tasks (each task modifies a post) scheduled in a short period of time, how can I ensure that each task is completed? I suspect that it is possible for the script to hit the maximum execution time during the loop. If that happens, there will be some posts that are not modified.

• Answer:

  You did not say how often you would need to modify posts in the background, or if you needed those posts to be all modified immediately, but let's assume that "soon" instead of is good enough. If yes then do your process into multiple steps. Schedule your cron task to run once per minute and each time do a small number of task, maybe 25 and just process them 25 at a time. That means that as long as your are getting at least one visitor a minute your 1000 tasks will be completed in less than 1 hour. However, if your plugin only knows what it needs to generate tasks at the time it generates all 1000 tasks then divide them into batches of task with maybe 25 tasks per batch. Then for each batch store the information you need to be able to modify those posts into an array, and use update_option() to serialize your data to the wp_options tables with option names (something) like "myplugin_batch1", "myplugin_batch2", "myplugin_batch3" and so on. Then when your cron fires each minute do a MySQL query of the wp_options table looking for the first record that has option_name LIKE 'myplugin_batch%' assuming the query sorts by option_name in ascending order. Use get_option() to retrieve and unserialize the value, run your updates, and then delete that option with delete_option(). Instead of using the wp_options table you could also use a "Task Batch" custom post type to store your "batches" and store your task information in post meta instead of a serialize array in the options table, your preference. However, if you must make all 1000 updates as quickly as possible you could do the first 25, then store all the information you need to update all the remaining 975 posts as a serialized array in a single option in the wp_options tables, schedule a new task to execute immediately, and then redirect to /wp-cron.php using wp_safe_redirect(). Your new scheduled task will then execute and it should load the serialized array from the wp_options table, pull out 25 tasks, do them, save the remaining tasks back to the single option in the wp_options tables, schedule another new task to execute immediately, and finally redirect to /wp-cron.php. If your new task loads and there is not anything left in your single option in the wp_options table then you are done and no need to redirect to /wp-cron.php. Hope this helps. Please let me know if it does.