From a0cd8ae8cbe14d2821cbe8fd6b011c4ddc729344 Mon Sep 17 00:00:00 2001 From: Erik Johnston Date: Fri, 4 Jun 2021 10:47:58 +0100 Subject: [PATCH] Don't try and backfill the same room in parallel. (#10116) If backfilling is slow then the client may time out and retry, causing Synapse to start a new `/backfill` before the existing backfill has finished, duplicating work. --- changelog.d/10116.bugfix | 1 + synapse/handlers/federation.py | 8 ++++++++ 2 files changed, 9 insertions(+) create mode 100644 changelog.d/10116.bugfix diff --git a/changelog.d/10116.bugfix b/changelog.d/10116.bugfix new file mode 100644 index 000000000000..90ef707559f8 --- /dev/null +++ b/changelog.d/10116.bugfix @@ -0,0 +1 @@ +Fix bug where the server would attempt to fetch the same history in the room from a remote server multiple times in parallel. diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py index f3f97db2fab9..b802822baaa2 100644 --- a/synapse/handlers/federation.py +++ b/synapse/handlers/federation.py @@ -178,6 +178,8 @@ def __init__(self, hs: "HomeServer"): self.room_queues = {} # type: Dict[str, List[Tuple[EventBase, str]]] self._room_pdu_linearizer = Linearizer("fed_room_pdu") + self._room_backfill = Linearizer("room_backfill") + self.third_party_event_rules = hs.get_third_party_event_rules() self._ephemeral_messages_enabled = hs.config.enable_ephemeral_messages @@ -1041,6 +1043,12 @@ async def maybe_backfill( return. This is used as part of the heuristic to decide if we should back paginate. """ + with (await self._room_backfill.queue(room_id)): + return await self._maybe_backfill_inner(room_id, current_depth, limit) + + async def _maybe_backfill_inner( + self, room_id: str, current_depth: int, limit: int + ) -> bool: extremities = await self.store.get_oldest_events_with_depth_in_room(room_id) if not extremities: