1 files changed, 23 insertions, 3 deletions
diff --git a/synapse/push/pusherpool.py b/synapse/push/pusherpool.py
index 76150e117b..f325964983 100644
--- a/synapse/push/pusherpool.py
+++ b/synapse/push/pusherpool.py
@@ -19,11 +19,15 @@ from typing import TYPE_CHECKING, Dict, Union
 
 from prometheus_client import Gauge
 
-from synapse.metrics.background_process_metrics import run_as_background_process
+from synapse.metrics.background_process_metrics import (
+    run_as_background_process,
+    wrap_as_background_process,
+)
 from synapse.push import PusherConfigException
 from synapse.push.emailpusher import EmailPusher
 from synapse.push.httppusher import HttpPusher
 from synapse.push.pusher import PusherFactory
+from synapse.types import RoomStreamToken
 from synapse.util.async_helpers import concurrently_execute
 
 if TYPE_CHECKING:
@@ -186,15 +190,31 @@ class PusherPool:
                 )
                 await self.remove_pusher(p["app_id"], p["pushkey"], p["user_name"])
 
-    async def on_new_notifications(self, max_stream_id: int):
+    def on_new_notifications(self, max_token: RoomStreamToken):
         if not self.pushers:
             # nothing to do here.
             return
 
+        # We just use the minimum stream ordering and ignore the vector clock
+        # component. This is safe to do as long as we *always* ignore the vector
+        # clock components.
+        max_stream_id = max_token.stream
+
         if max_stream_id < self._last_room_stream_id_seen:
             # Nothing to do
             return
 
+        # We only start a new background process if necessary rather than
+        # optimistically (to cut down on overhead).
+        self._on_new_notifications(max_token)
+
+    @wrap_as_background_process("on_new_notifications")
+    async def _on_new_notifications(self, max_token: RoomStreamToken):
+        # We just use the minimum stream ordering and ignore the vector clock
+        # component. This is safe to do as long as we *always* ignore the vector
+        # clock components.
+        max_stream_id = max_token.stream
+
         prev_stream_id = self._last_room_stream_id_seen
         self._last_room_stream_id_seen = max_stream_id
 
@@ -214,7 +234,7 @@ class PusherPool:
 
                 if u in self.pushers:
                     for p in self.pushers[u].values():
-                        p.on_new_notifications(max_stream_id)
+                        p.on_new_notifications(max_token)
 
         except Exception:
             logger.exception("Exception in pusher on_new_notifications")