diff --git a/changelog.d/4748.misc b/changelog.d/4748.misc
new file mode 100644
index 0000000000..4dc18378e7
--- /dev/null
+++ b/changelog.d/4748.misc
@@ -0,0 +1 @@
+Improve replication performance by reducing cache invalidation traffic.
diff --git a/synapse/replication/tcp/protocol.py b/synapse/replication/tcp/protocol.py
index 0b3fe6cbf5..429471c345 100644
--- a/synapse/replication/tcp/protocol.py
+++ b/synapse/replication/tcp/protocol.py
@@ -268,7 +268,17 @@ class BaseReplicationStreamProtocol(LineOnlyReceiver):
if "\n" in string:
raise Exception("Unexpected newline in command: %r", string)
- self.sendLine(string.encode("utf-8"))
+ encoded_string = string.encode("utf-8")
+
+ if len(encoded_string) > self.MAX_LENGTH:
+ raise Exception(
+ "Failed to send command %s as too long (%d > %d)" % (
+ cmd.NAME,
+ len(encoded_string), self.MAX_LENGTH,
+ )
+ )
+
+ self.sendLine(encoded_string)
self.last_sent_command = self.clock.time_msec()
@@ -361,6 +371,11 @@ class BaseReplicationStreamProtocol(LineOnlyReceiver):
def id(self):
return "%s-%s" % (self.name, self.conn_id)
+ def lineLengthExceeded(self, line):
+ """Called when we receive a line that is above the maximum line length
+ """
+ self.send_error("Line length exceeded")
+
class ServerReplicationStreamProtocol(BaseReplicationStreamProtocol):
VALID_INBOUND_COMMANDS = VALID_CLIENT_COMMANDS
diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index 190be34fb1..a0333d5309 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -30,6 +30,7 @@ from synapse.api.errors import StoreError
from synapse.metrics.background_process_metrics import run_as_background_process
from synapse.storage.engines import PostgresEngine, Sqlite3Engine
from synapse.types import get_domain_from_id
+from synapse.util import batch_iter
from synapse.util.caches.descriptors import Cache
from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
from synapse.util.stringutils import exception_to_unicode
@@ -1327,10 +1328,16 @@ class SQLBaseStore(object):
"""
txn.call_after(self._invalidate_state_caches, room_id, members_changed)
- keys = itertools.chain([room_id], members_changed)
- self._send_invalidation_to_replication(
- txn, _CURRENT_STATE_CACHE_NAME, keys,
- )
+ # We need to be careful that the size of the `members_changed` list
+ # isn't so large that it causes problems sending over replication, so we
+ # send them in chunks.
+ # Max line length is 16K, and max user ID length is 255, so 50 should
+ # be safe.
+ for chunk in batch_iter(members_changed, 50):
+ keys = itertools.chain([room_id], chunk)
+ self._send_invalidation_to_replication(
+ txn, _CURRENT_STATE_CACHE_NAME, keys,
+ )
def _invalidate_state_caches(self, room_id, members_changed):
"""Invalidates caches that are based on the current state, but does
|
