diff --git a/core/lib/Drupal/Core/Lock/LockBackendInterface.php b/core/lib/Drupal/Core/Lock/LockBackendInterface.php
index c84e42d..25a8133 100644
--- a/core/lib/Drupal/Core/Lock/LockBackendInterface.php
+++ b/core/lib/Drupal/Core/Lock/LockBackendInterface.php
@@ -14,11 +14,12 @@
  *
  * In most environments, multiple Drupal page requests (a.k.a. threads or
  * processes) will execute in parallel. This leads to potential conflicts or
- * race conditions when two requests execute the same code at the same time. A
- * common example of this is a rebuild like menu_router_rebuild() where we
- * invoke many hook implementations to get and process data from all active
- * modules, and then delete the current data in the database to insert the new
- * afterwards.
+ * race conditions when two requests execute the same code at the same time. For
+ * instance, aggregator_cron() queues items from its feeds to import before
+ * updating their status, so this code must not run in parallel in order to
+ * prevent double-queued/imported items. This is one example of why
+ * \Drupal\Core\Cron::run() must disallow parallel execution using a locking
+ * mechanism.
  *
  * This is a cooperative, advisory lock system. Any long-running operation
  * that could potentially be attempted in parallel by multiple requests should