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Handle replication commands synchronously where possible (#7876) 

Most of the stuff we do for replication commands can be done synchronously. There's no point spinning up background processes if we're not going to need them.
This commit is contained in:
Richard van der Hoff 2020-07-27 18:54:43 +01:00 committed by GitHub
parent 7c2e2c2077
commit f57b99af22
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5 changed files with 113 additions and 86 deletions
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1
changelog.d/7876.bugfix Normal file
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@ -0,0 +1 @@
Fix an `AssertionError` exception introduced in v1.18.0rc1.

1
changelog.d/7876.misc Normal file
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@ -0,0 +1 @@
Further optimise queueing of inbound replication commands.

89
synapse/replication/tcp/handler.py
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@ -16,6 +16,7 @@
import logging
from typing import (
Any,
Awaitable,
Dict,
Iterable,
Iterator,
@ -33,6 +34,7 @@ from typing_extensions import Deque
from twisted.internet.protocol import ReconnectingClientFactory
from synapse.metrics import LaterGauge
from synapse.metrics.background_process_metrics import run_as_background_process
from synapse.replication.tcp.client import DirectTcpReplicationClientFactory
from synapse.replication.tcp.commands import (
ClearUserSyncsCommand,
@ -152,7 +154,7 @@ class ReplicationCommandHandler:
# When POSITION or RDATA commands arrive, we stick them in a queue and process
# them in order in a separate background process.
# the streams which are currently being processed by _unsafe_process_stream
# the streams which are currently being processed by _unsafe_process_queue
self._processing_streams = set() # type: Set[str]
# for each stream, a queue of commands that are awaiting processing, and the
@ -185,7 +187,7 @@ class ReplicationCommandHandler:
if self._is_master:
self._server_notices_sender = hs.get_server_notices_sender()
async def _add_command_to_stream_queue(
def _add_command_to_stream_queue(
self, conn: AbstractConnection, cmd: Union[RdataCommand, PositionCommand]
) -> None:
"""Queue the given received command for processing
@ -199,33 +201,34 @@ class ReplicationCommandHandler:
logger.error("Got %s for unknown stream: %s", cmd.NAME, stream_name)
return
# if we're already processing this stream, stick the new command in the
# queue, and we're done.
if stream_name in self._processing_streams:
queue.append((cmd, conn))
# if we're already processing this stream, there's nothing more to do:
# the new entry on the queue will get picked up in due course
if stream_name in self._processing_streams:
return
# otherwise, process the new command.
# fire off a background process to start processing the queue.
run_as_background_process(
"process-replication-data", self._unsafe_process_queue, stream_name
)
# arguably we should start off a new background process here, but nothing
# will be too upset if we don't return for ages, so let's save the overhead
# and use the existing logcontext.
async def _unsafe_process_queue(self, stream_name: str):
"""Processes the command queue for the given stream, until it is empty
Does not check if there is already a thread processing the queue, hence "unsafe"
"""
assert stream_name not in self._processing_streams
self._processing_streams.add(stream_name)
try:
# might as well skip the queue for this one, since it must be empty
assert not queue
await self._process_command(cmd, conn, stream_name)
# now process any other commands that have built up while we were
# dealing with that one.
queue = self._command_queues_by_stream.get(stream_name)
while queue:
cmd, conn = queue.popleft()
try:
await self._process_command(cmd, conn, stream_name)
except Exception:
logger.exception("Failed to handle command %s", cmd)
finally:
self._processing_streams.discard(stream_name)
@ -299,7 +302,7 @@ class ReplicationCommandHandler:
"""
return self._streams_to_replicate
async def on_REPLICATE(self, conn: AbstractConnection, cmd: ReplicateCommand):
def on_REPLICATE(self, conn: AbstractConnection, cmd: ReplicateCommand):
self.send_positions_to_connection(conn)
def send_positions_to_connection(self, conn: AbstractConnection):
@ -318,44 +321,60 @@ class ReplicationCommandHandler:
)
)
async def on_USER_SYNC(self, conn: AbstractConnection, cmd: UserSyncCommand):
def on_USER_SYNC(
self, conn: AbstractConnection, cmd: UserSyncCommand
) -> Optional[Awaitable[None]]:
user_sync_counter.inc()
if self._is_master:
await self._presence_handler.update_external_syncs_row(
return self._presence_handler.update_external_syncs_row(
cmd.instance_id, cmd.user_id, cmd.is_syncing, cmd.last_sync_ms
)
else:
return None
async def on_CLEAR_USER_SYNC(
def on_CLEAR_USER_SYNC(
self, conn: AbstractConnection, cmd: ClearUserSyncsCommand
):
) -> Optional[Awaitable[None]]:
if self._is_master:
await self._presence_handler.update_external_syncs_clear(cmd.instance_id)
return self._presence_handler.update_external_syncs_clear(cmd.instance_id)
else:
return None
async def on_FEDERATION_ACK(
self, conn: AbstractConnection, cmd: FederationAckCommand
):
def on_FEDERATION_ACK(self, conn: AbstractConnection, cmd: FederationAckCommand):
federation_ack_counter.inc()
if self._federation_sender:
self._federation_sender.federation_ack(cmd.instance_name, cmd.token)
async def on_REMOVE_PUSHER(
def on_REMOVE_PUSHER(
self, conn: AbstractConnection, cmd: RemovePusherCommand
):
) -> Optional[Awaitable[None]]:
remove_pusher_counter.inc()
if self._is_master:
return self._handle_remove_pusher(cmd)
else:
return None
async def _handle_remove_pusher(self, cmd: RemovePusherCommand):
await self._store.delete_pusher_by_app_id_pushkey_user_id(
app_id=cmd.app_id, pushkey=cmd.push_key, user_id=cmd.user_id
)
self._notifier.on_new_replication_data()
async def on_USER_IP(self, conn: AbstractConnection, cmd: UserIpCommand):
def on_USER_IP(
self, conn: AbstractConnection, cmd: UserIpCommand
) -> Optional[Awaitable[None]]:
user_ip_cache_counter.inc()
if self._is_master:
return self._handle_user_ip(cmd)
else:
return None
async def _handle_user_ip(self, cmd: UserIpCommand):
await self._store.insert_client_ip(
cmd.user_id,
cmd.access_token,
@ -365,10 +384,10 @@ class ReplicationCommandHandler:
cmd.last_seen,
)
if self._server_notices_sender:
assert self._server_notices_sender is not None
await self._server_notices_sender.on_user_ip(cmd.user_id)
async def on_RDATA(self, conn: AbstractConnection, cmd: RdataCommand):
def on_RDATA(self, conn: AbstractConnection, cmd: RdataCommand):
if cmd.instance_name == self._instance_name:
# Ignore RDATA that are just our own echoes
return
@ -382,7 +401,7 @@ class ReplicationCommandHandler:
# 2. so we don't race with getting a POSITION command and fetching
# missing RDATA.
await self._add_command_to_stream_queue(conn, cmd)
self._add_command_to_stream_queue(conn, cmd)
async def _process_rdata(
self, stream_name: str, conn: AbstractConnection, cmd: RdataCommand
@ -459,14 +478,14 @@ class ReplicationCommandHandler:
stream_name, instance_name, token, rows
)
async def on_POSITION(self, conn: AbstractConnection, cmd: PositionCommand):
def on_POSITION(self, conn: AbstractConnection, cmd: PositionCommand):
if cmd.instance_name == self._instance_name:
# Ignore POSITION that are just our own echoes
return
logger.info("Handling '%s %s'", cmd.NAME, cmd.to_line())
await self._add_command_to_stream_queue(conn, cmd)
self._add_command_to_stream_queue(conn, cmd)
async def _process_position(
self, stream_name: str, conn: AbstractConnection, cmd: PositionCommand
@ -526,9 +545,7 @@ class ReplicationCommandHandler:
self._streams_by_connection.setdefault(conn, set()).add(stream_name)
async def on_REMOTE_SERVER_UP(
self, conn: AbstractConnection, cmd: RemoteServerUpCommand
):
def on_REMOTE_SERVER_UP(self, conn: AbstractConnection, cmd: RemoteServerUpCommand):
""""Called when get a new REMOTE_SERVER_UP command."""
self._replication_data_handler.on_remote_server_up(cmd.data)

45
synapse/replication/tcp/protocol.py
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@ -50,6 +50,7 @@ import abc
import fcntl
import logging
import struct
from inspect import isawaitable
from typing import TYPE_CHECKING, List
from prometheus_client import Counter
@ -128,6 +129,8 @@ class BaseReplicationStreamProtocol(LineOnlyReceiver):
On receiving a new command it calls `on_<COMMAND_NAME>` with the parsed
command before delegating to `ReplicationCommandHandler.on_<COMMAND_NAME>`.
`ReplicationCommandHandler.on_<COMMAND_NAME>` can optionally return a coroutine;
if so, that will get run as a background process.
It also sends `PING` periodically, and correctly times out remote connections
(if they send a `PING` command)
@ -166,9 +169,9 @@ class BaseReplicationStreamProtocol(LineOnlyReceiver):
# a logcontext which we use for processing incoming commands. We declare it as a
# background process so that the CPU stats get reported to prometheus.
self._logging_context = BackgroundProcessLoggingContext(
"replication_command_handler-%s" % self.conn_id
)
ctx_name = "replication-conn-%s" % self.conn_id
self._logging_context = BackgroundProcessLoggingContext(ctx_name)
self._logging_context.request = ctx_name
def connectionMade(self):
logger.info("[%s] Connection established", self.id())
@ -246,18 +249,17 @@ class BaseReplicationStreamProtocol(LineOnlyReceiver):
tcp_inbound_commands_counter.labels(cmd.NAME, self.name).inc()
# Now lets try and call on_<CMD_NAME> function
run_as_background_process(
"replication-" + cmd.get_logcontext_id(), self.handle_command, cmd
)
self.handle_command(cmd)
async def handle_command(self, cmd: Command):
def handle_command(self, cmd: Command) -> None:
"""Handle a command we have received over the replication stream.
First calls `self.on_<COMMAND>` if it exists, then calls
`self.command_handler.on_<COMMAND>` if it exists. This allows for
protocol level handling of commands (e.g. PINGs), before delegating to
the handler.
`self.command_handler.on_<COMMAND>` if it exists (which can optionally
return an Awaitable).
This allows for protocol level handling of commands (e.g. PINGs), before
delegating to the handler.
Args:
cmd: received command
@ -268,13 +270,22 @@ class BaseReplicationStreamProtocol(LineOnlyReceiver):
# specific handling.
cmd_func = getattr(self, "on_%s" % (cmd.NAME,), None)
if cmd_func:
await cmd_func(cmd)
cmd_func(cmd)
handled = True
# Then call out to the handler.
cmd_func = getattr(self.command_handler, "on_%s" % (cmd.NAME,), None)
if cmd_func:
await cmd_func(self, cmd)
res = cmd_func(self, cmd)
# the handler might be a coroutine: fire it off as a background process
# if so.
if isawaitable(res):
run_as_background_process(
"replication-" + cmd.get_logcontext_id(), lambda: res
)
handled = True
if not handled:
@ -350,10 +361,10 @@ class BaseReplicationStreamProtocol(LineOnlyReceiver):
for cmd in pending:
self.send_command(cmd)
async def on_PING(self, line):
def on_PING(self, line):
self.received_ping = True
async def on_ERROR(self, cmd):
def on_ERROR(self, cmd):
logger.error("[%s] Remote reported error: %r", self.id(), cmd.data)
def pauseProducing(self):
@ -448,7 +459,7 @@ class ServerReplicationStreamProtocol(BaseReplicationStreamProtocol):
self.send_command(ServerCommand(self.server_name))
super().connectionMade()
async def on_NAME(self, cmd):
def on_NAME(self, cmd):
logger.info("[%s] Renamed to %r", self.id(), cmd.data)
self.name = cmd.data
@ -477,7 +488,7 @@ class ClientReplicationStreamProtocol(BaseReplicationStreamProtocol):
# Once we've connected subscribe to the necessary streams
self.replicate()
async def on_SERVER(self, cmd):
def on_SERVER(self, cmd):
if cmd.data != self.server_name:
logger.error("[%s] Connected to wrong remote: %r", self.id(), cmd.data)
self.send_error("Wrong remote")

37
synapse/replication/tcp/redis.py
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@ -14,6 +14,7 @@
# limitations under the License.
import logging
from inspect import isawaitable
from typing import TYPE_CHECKING
import txredisapi
@ -124,36 +125,32 @@ class RedisSubscriber(txredisapi.SubscriberProtocol, AbstractConnection):
# remote instances.
tcp_inbound_commands_counter.labels(cmd.NAME, "redis").inc()
# Now lets try and call on_<CMD_NAME> function
run_as_background_process(
"replication-" + cmd.get_logcontext_id(), self.handle_command, cmd
)
self.handle_command(cmd)
async def handle_command(self, cmd: Command):
def handle_command(self, cmd: Command) -> None:
"""Handle a command we have received over the replication stream.
By default delegates to on_<COMMAND>, which should return an awaitable.
Delegates to `self.handler.on_<COMMAND>` (which can optionally return an
Awaitable).
Args:
cmd: received command
"""
handled = False
# First call any command handlers on this instance. These are for redis
# specific handling.
cmd_func = getattr(self, "on_%s" % (cmd.NAME,), None)
if cmd_func:
await cmd_func(cmd)
handled = True
# Then call out to the handler.
cmd_func = getattr(self.handler, "on_%s" % (cmd.NAME,), None)
if cmd_func:
await cmd_func(self, cmd)
handled = True
if not handled:
if not cmd_func:
logger.warning("Unhandled command: %r", cmd)
return
res = cmd_func(self, cmd)
# the handler might be a coroutine: fire it off as a background process
# if so.
if isawaitable(res):
run_as_background_process(
"replication-" + cmd.get_logcontext_id(), lambda: res
)
def connectionLost(self, reason):
logger.info("Lost connection to redis")