WordPress: Cron locking and Queue

Simple Cronjob Walker

1. Create a CPT cronjob for your cronjobs.
2. Add the relevant post meta data (action, last_executed,… and whatever you need)

3. Create a walker function

   function my_cronjob_walker() {
       $args= array(
           'post_type' => 'cronjob',
           'posts_per_page' => 1,
           'meta_key' => 'last_executed'
           'orderby' => 'meta_value',
       );
       $cronjob = new WP_Query($args);
       if ($cronjob->have_posts()) while ($cronjob->have_posts()) {
           $cronjob->the_post();
           // do your cronjob stuff here
           do_action(get_post_meta(get_the_ID(), 'action', true);
           update_post_meta(get_the_ID(), 'last_executed', date('c'));
       }
   }
   if ( ! wp_next_scheduled( 'do_cronjob_walker' ) ) {
       wp_schedule_event( time(), 'hourly', 'do_cronjob_walker' );
   }
   
   add_action( 'do_cronjob_walker', 'my_cronjob_walker' );