All classes that implement DelayableQueueInterface in Drupal 9
- class \Drupal\Core\Queue\Batch
- class \Drupal\Core\Queue\DatabaseQueue implements DelayableQueueInterface, QueueGarbageCollectionInterface, ReliableQueueInterface uses DependencySerializationTrait
- class \Drupal\salesforce_push\PushQueue implements PushQueueInterface
- class \Drupal\simple_sitemap\Queue\SimpleSitemapQueue