Limit cache invalidation replication line length (#4748)

This commit is contained in:
Erik Johnston 2019-02-27 10:28:37 +00:00 committed by Richard van der Hoff
parent f191be822b
commit 6bb1c028f1
3 changed files with 28 additions and 5 deletions

1
changelog.d/4748.misc Normal file
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@ -0,0 +1 @@
Improve replication performance by reducing cache invalidation traffic.

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@ -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

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@ -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
@ -1327,7 +1328,13 @@ class SQLBaseStore(object):
"""
txn.call_after(self._invalidate_state_caches, room_id, members_changed)
keys = itertools.chain([room_id], members_changed)
# 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,
)