diff -u b/core/lib/Drupal/Core/EventSubscriber/MenuRouterRebuildSubscriber.php b/core/lib/Drupal/Core/EventSubscriber/MenuRouterRebuildSubscriber.php
--- b/core/lib/Drupal/Core/EventSubscriber/MenuRouterRebuildSubscriber.php
+++ b/core/lib/Drupal/Core/EventSubscriber/MenuRouterRebuildSubscriber.php
@@ -59,7 +59,18 @@
    * Perform menu-specific rebuilding.
    */
   protected function menuLinksRebuild() {
-    $this->menuLinkManager->rebuild();
+    if ($this->lock->acquire(__FUNCTION__)) {
+      // Ensure the menu links are up to date.
+      $this->menuLinkManager->rebuild();
+
+      $this->lock->release(__FUNCTION__);
+    }
+    else {
+      // Wait for another request that is already doing this work.
+      // We choose to block here since otherwise the router item may not
+      // be available during routing resulting in a 404.
+      $this->lock->wait(__FUNCTION__);
+    }
   }
 
   /**
diff -u b/core/lib/Drupal/Core/Menu/MenuTreeStorage.php b/core/lib/Drupal/Core/Menu/MenuTreeStorage.php
--- b/core/lib/Drupal/Core/Menu/MenuTreeStorage.php
+++ b/core/lib/Drupal/Core/Menu/MenuTreeStorage.php
@@ -147,25 +147,14 @@
    * {@inheritdoc}
    */
   public function rebuild(array $definitions) {
-    if ($this->lock->acquire(__FUNCTION__)) {
-      $transaction = $this->connection->startTransaction();
-      try {
-        // Ensure the menu links are up to date.
-        $this->menuLinkManager->rebuild();
-        // Ignore any database replicas temporarily.
-        db_ignore_replica();
-      }
-      catch (\Exception $e) {
-        $transaction->rollback();
-        watchdog_exception('menu', $e);
-      }
-      $this->lock->release(__FUNCTION__);
+    $transaction = $this->connection->startTransaction();
+    try {
+      // Ignore any database replicas temporarily.
+      db_ignore_replica();
     }
-    else {
-      // Wait for another request that is already doing this work.
-      // We choose to block here since otherwise the router item may not
-      // be available during routing resulting in a 404.
-      $this->lock->wait(__FUNCTION__);
+    catch (\Exception $e) {
+      $transaction->rollback();
+      watchdog_exception('menu', $e);
     }
 
     $links = array();