1 files changed, 3 insertions, 0 deletions
diff --git a/synapse/app/generic_worker.py b/synapse/app/generic_worker.py
index d596852419..cdc078cf11 100644
--- a/synapse/app/generic_worker.py
+++ b/synapse/app/generic_worker.py
@@ -775,6 +775,9 @@ class FederationSenderHandler(object):
 
         # ... as well as device updates and messages
         elif stream_name == DeviceListsStream.NAME:
+            # The entities are either user IDs (starting with '@') whose devices
+            # have changed, or remote servers that we need to tell about
+            # changes.
             hosts = {row.entity for row in rows if not row.entity.startswith("@")}
             for host in hosts:
                 self.federation_sender.send_device_messages(host)