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.
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Erik Johnston 2021-06-04 10:47:58 +01:00 committed by GitHub
parent c96ab31dff
commit a0cd8ae8cb
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2 changed files with 9 additions and 0 deletions

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changelog.d/10116.bugfix Normal file
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@ -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.

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@ -178,6 +178,8 @@ class FederationHandler(BaseHandler):
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 @@ class FederationHandler(BaseHandler):
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: