Update to Drupal 8.0.2. For more information, see https://www.drupal.org/drupal-8.0.2-release-notes

core/lib/Drupal/Core/Annotation/QueueWorker.php

@@ -10,18 +10,21 @@ namespace Drupal\Core\Annotation;
 use Drupal\Component\Annotation\Plugin;
 
 /**
- * Declare queue workers that need to be run periodically.
+ * Declare a worker class for processing a queue item.
  *
- * While there can be only one hook_cron() process running at the same time,
- * there can be any number of processes defined here running. Because of
- * this, long running tasks are much better suited for this API. Items queued
- * in hook_cron() might be processed in the same cron run if there are not many
- * items in the queue, otherwise it might take several requests, which can be
- * run in parallel.
+ * Worker plugins are used by some queues for processing the individual items
+ * in the queue. In that case, the ID of the worker plugin needs to match the
+ * machine name of a queue, so that you can retrieve the queue back end by
+ * calling \Drupal\Core\Queue\QueueFactory::get($plugin_id).
  *
- * You can create queues, add items to them, claim them, etc. without using a
- * QueueWorker plugin if you want, however, you need to take care of processing
- * the items in the queue in that case. See \Drupal\Core\Cron for an example.
+ * \Drupal\Core\Cron::processQueues() processes queues that use workers; they
+ * can also be processed outside of the cron process.
+ *
+ * Some queues do not use worker plugins: you can create queues, add items to
+ * them, claim them, etc. without using a QueueWorker plugin. However, you will
+ * need to take care of processing the items in the queue in that case. You can
+ * look at \Drupal\Core\Cron::processQueues() for an example of how to process
+ * a queue that uses workers, and adapt it to your queue.
  *
  * Plugin Namespace: Plugin\QueueWorker
  *