diff options
| -rw-r--r-- | changelog.d/16557.bugfix | 1 | ||||
| -rw-r--r-- | synapse/replication/tcp/resource.py | 19 |
2 files changed, 19 insertions, 1 deletions
diff --git a/changelog.d/16557.bugfix b/changelog.d/16557.bugfix new file mode 100644 index 0000000000..4f4a0380cd --- /dev/null +++ b/changelog.d/16557.bugfix @@ -0,0 +1 @@ +Fix a long-standing, exceedingly rare edge case where the first event persisted by a new event persister worker might not be sent down `/sync`. diff --git a/synapse/replication/tcp/resource.py b/synapse/replication/tcp/resource.py index 1d9a29d22e..38abb5df54 100644 --- a/synapse/replication/tcp/resource.py +++ b/synapse/replication/tcp/resource.py @@ -27,7 +27,7 @@ from synapse.metrics.background_process_metrics import run_as_background_process from synapse.replication.tcp.commands import PositionCommand from synapse.replication.tcp.protocol import ServerReplicationStreamProtocol from synapse.replication.tcp.streams import EventsStream -from synapse.replication.tcp.streams._base import StreamRow, Token +from synapse.replication.tcp.streams._base import CachesStream, StreamRow, Token from synapse.util.metrics import Measure if TYPE_CHECKING: @@ -204,6 +204,23 @@ class ReplicationStreamer: # The token has advanced but there is no data to # send, so we send a `POSITION` to inform other # workers of the updated position. + # + # There are two reasons for this: 1) this instance + # requested a stream ID but didn't use it, or 2) + # this instance advanced its own stream position due + # to receiving notifications about other instances + # advancing their stream position. + + # We skip sending `POSITION` for the `caches` stream + # for the second case as a) it generates a lot of + # traffic as every worker would echo each write, and + # b) nothing cares if a given worker's caches stream + # position lags. + if stream.NAME == CachesStream.NAME: + # If there haven't been any writes since the + # `last_token` then we're in the second case. + if stream.minimal_local_current_token() <= last_token: + continue # Note: `last_token` may not *actually* be the # last token we sent out in a RDATA or POSITION. |