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Don't go into federation catch up mode so easily (#9561) 

Federation catch up mode is very inefficient if the number of events
that the remote server has missed is small, since handling gaps can be
very expensive, c.f. #9492.

Instead of going into catch up mode whenever we see an error, we instead
do so only if we've backed off from trying the remote for more than an
hour (the assumption being that in such a case it is more than a
transient failure).
pull/9618/head
Erik Johnston 2021-03-15 14:42:40 +00:00 committed by GitHub
parent af2248f8bf
commit 026503fa3b
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GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 189 additions and 158 deletions
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1
changelog.d/9561.misc Normal file
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@ -0,0 +1 @@
Increase the threshold before which outbound federation to a server goes into "catch up" mode, which is expensive for the remote server to handle.

289
synapse/federation/sender/per_destination_queue.py
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@ -17,6 +17,7 @@ import datetime
import logging
from typing import TYPE_CHECKING, Dict, Hashable, Iterable, List, Optional, Tuple, cast
import attr
from prometheus_client import Counter
from synapse.api.errors import (
@ -93,6 +94,10 @@ class PerDestinationQueue:
self._destination = destination
self.transmission_loop_running = False
# Flag to signal to any running transmission loop that there is new data
# queued up to be sent.
self._new_data_to_send = False
# True whilst we are sending events that the remote homeserver missed
# because it was unreachable. We start in this state so we can perform
# catch-up at startup.
@ -108,7 +113,7 @@ class PerDestinationQueue:
# destination (we are the only updater so this is safe)
self._last_successful_stream_ordering = None # type: Optional[int]
# a list of pending PDUs
# a queue of pending PDUs
self._pending_pdus = [] # type: List[EventBase]
# XXX this is never actually used: see
@ -208,6 +213,10 @@ class PerDestinationQueue:
transaction in the background.
"""
# Mark that we (may) have new things to send, so that any running
# transmission loop will recheck whether there is stuff to send.
self._new_data_to_send = True
if self.transmission_loop_running:
# XXX: this can get stuck on by a never-ending
# request at which point pending_pdus just keeps growing.
@ -250,125 +259,41 @@ class PerDestinationQueue:
pending_pdus = []
while True:
# We have to keep 2 free slots for presence and rr_edus
limit = MAX_EDUS_PER_TRANSACTION - 2
self._new_data_to_send = False
device_update_edus, dev_list_id = await self._get_device_update_edus(
limit
)
limit -= len(device_update_edus)
(
to_device_edus,
device_stream_id,
) = await self._get_to_device_message_edus(limit)
pending_edus = device_update_edus + to_device_edus
# BEGIN CRITICAL SECTION
#
# In order to avoid a race condition, we need to make sure that
# the following code (from popping the queues up to the point
# where we decide if we actually have any pending messages) is
# atomic - otherwise new PDUs or EDUs might arrive in the
# meantime, but not get sent because we hold the
# transmission_loop_running flag.
pending_pdus = self._pending_pdus
# We can only include at most 50 PDUs per transactions
pending_pdus, self._pending_pdus = pending_pdus[:50], pending_pdus[50:]
pending_edus.extend(self._get_rr_edus(force_flush=False))
pending_presence = self._pending_presence
self._pending_presence = {}
if pending_presence:
pending_edus.append(
Edu(
origin=self._server_name,
destination=self._destination,
edu_type="m.presence",
content={
"push": [
format_user_presence_state(
presence, self._clock.time_msec()
)
for presence in pending_presence.values()
]
},
)
)
pending_edus.extend(
self._pop_pending_edus(MAX_EDUS_PER_TRANSACTION - len(pending_edus))
)
while (
len(pending_edus) < MAX_EDUS_PER_TRANSACTION
and self._pending_edus_keyed
async with _TransactionQueueManager(self) as (
pending_pdus,
pending_edus,
):
_, val = self._pending_edus_keyed.popitem()
pending_edus.append(val)
if not pending_pdus and not pending_edus:
logger.debug("TX [%s] Nothing to send", self._destination)
if pending_pdus:
logger.debug(
"TX [%s] len(pending_pdus_by_dest[dest]) = %d",
self._destination,
len(pending_pdus),
# If we've gotten told about new things to send during
# checking for things to send, we try looking again.
# Otherwise new PDUs or EDUs might arrive in the meantime,
# but not get sent because we hold the
# `transmission_loop_running` flag.
if self._new_data_to_send:
continue
else:
return
if pending_pdus:
logger.debug(
"TX [%s] len(pending_pdus_by_dest[dest]) = %d",
self._destination,
len(pending_pdus),
)
await self._transaction_manager.send_new_transaction(
self._destination, pending_pdus, pending_edus
)
if not pending_pdus and not pending_edus:
logger.debug("TX [%s] Nothing to send", self._destination)
self._last_device_stream_id = device_stream_id
return
# if we've decided to send a transaction anyway, and we have room, we
# may as well send any pending RRs
if len(pending_edus) < MAX_EDUS_PER_TRANSACTION:
pending_edus.extend(self._get_rr_edus(force_flush=True))
# END CRITICAL SECTION
success = await self._transaction_manager.send_new_transaction(
self._destination, pending_pdus, pending_edus
)
if success:
sent_transactions_counter.inc()
sent_edus_counter.inc(len(pending_edus))
for edu in pending_edus:
sent_edus_by_type.labels(edu.edu_type).inc()
# Remove the acknowledged device messages from the database
# Only bother if we actually sent some device messages
if to_device_edus:
await self._store.delete_device_msgs_for_remote(
self._destination, device_stream_id
)
# also mark the device updates as sent
if device_update_edus:
logger.info(
"Marking as sent %r %r", self._destination, dev_list_id
)
await self._store.mark_as_sent_devices_by_remote(
self._destination, dev_list_id
)
self._last_device_stream_id = device_stream_id
self._last_device_list_stream_id = dev_list_id
if pending_pdus:
# we sent some PDUs and it was successful, so update our
# last_successful_stream_ordering in the destinations table.
final_pdu = pending_pdus[-1]
last_successful_stream_ordering = (
final_pdu.internal_metadata.stream_ordering
)
assert last_successful_stream_ordering
await self._store.set_destination_last_successful_stream_ordering(
self._destination, last_successful_stream_ordering
)
else:
break
except NotRetryingDestination as e:
logger.debug(
"TX [%s] not ready for retry yet (next retry at %s) - "
@ -401,7 +326,7 @@ class PerDestinationQueue:
self._pending_presence = {}
self._pending_rrs = {}
self._start_catching_up()
self._start_catching_up()
except FederationDeniedError as e:
logger.info(e)
except HttpResponseException as e:
@ -412,7 +337,6 @@ class PerDestinationQueue:
e,
)
self._start_catching_up()
except RequestSendFailed as e:
logger.warning(
"TX [%s] Failed to send transaction: %s", self._destination, e
@ -422,16 +346,12 @@ class PerDestinationQueue:
logger.info(
"Failed to send event %s to %s", p.event_id, self._destination
)
self._start_catching_up()
except Exception:
logger.exception("TX [%s] Failed to send transaction", self._destination)
for p in pending_pdus:
logger.info(
"Failed to send event %s to %s", p.event_id, self._destination
)
self._start_catching_up()
finally:
# We want to be *very* sure we clear this after we stop processing
self.transmission_loop_running = False
@ -499,13 +419,10 @@ class PerDestinationQueue:
rooms = [p.room_id for p in catchup_pdus]
logger.info("Catching up rooms to %s: %r", self._destination, rooms)
success = await self._transaction_manager.send_new_transaction(
await self._transaction_manager.send_new_transaction(
self._destination, catchup_pdus, []
)
if not success:
return
sent_transactions_counter.inc()
final_pdu = catchup_pdus[-1]
self._last_successful_stream_ordering = cast(
@ -584,3 +501,135 @@ class PerDestinationQueue:
"""
self._catching_up = True
self._pending_pdus = []
@attr.s(slots=True)
class _TransactionQueueManager:
"""A helper async context manager for pulling stuff off the queues and
tracking what was last successfully sent, etc.
"""
queue = attr.ib(type=PerDestinationQueue)
_device_stream_id = attr.ib(type=Optional[int], default=None)
_device_list_id = attr.ib(type=Optional[int], default=None)
_last_stream_ordering = attr.ib(type=Optional[int], default=None)
_pdus = attr.ib(type=List[EventBase], factory=list)
async def __aenter__(self) -> Tuple[List[EventBase], List[Edu]]:
# First we calculate the EDUs we want to send, if any.
# We start by fetching device related EDUs, i.e device updates and to
# device messages. We have to keep 2 free slots for presence and rr_edus.
limit = MAX_EDUS_PER_TRANSACTION - 2
device_update_edus, dev_list_id = await self.queue._get_device_update_edus(
limit
)
if device_update_edus:
self._device_list_id = dev_list_id
else:
self.queue._last_device_list_stream_id = dev_list_id
limit -= len(device_update_edus)
(
to_device_edus,
device_stream_id,
) = await self.queue._get_to_device_message_edus(limit)
if to_device_edus:
self._device_stream_id = device_stream_id
else:
self.queue._last_device_stream_id = device_stream_id
pending_edus = device_update_edus + to_device_edus
# Now add the read receipt EDU.
pending_edus.extend(self.queue._get_rr_edus(force_flush=False))
# And presence EDU.
if self.queue._pending_presence:
pending_edus.append(
Edu(
origin=self.queue._server_name,
destination=self.queue._destination,
edu_type="m.presence",
content={
"push": [
format_user_presence_state(
presence, self.queue._clock.time_msec()
)
for presence in self.queue._pending_presence.values()
]
},
)
)
self.queue._pending_presence = {}
# Finally add any other types of EDUs if there is room.
pending_edus.extend(
self.queue._pop_pending_edus(MAX_EDUS_PER_TRANSACTION - len(pending_edus))
)
while (
len(pending_edus) < MAX_EDUS_PER_TRANSACTION
and self.queue._pending_edus_keyed
):
_, val = self.queue._pending_edus_keyed.popitem()
pending_edus.append(val)
# Now we look for any PDUs to send, by getting up to 50 PDUs from the
# queue
self._pdus = self.queue._pending_pdus[:50]
if not self._pdus and not pending_edus:
return [], []
# if we've decided to send a transaction anyway, and we have room, we
# may as well send any pending RRs
if len(pending_edus) < MAX_EDUS_PER_TRANSACTION:
pending_edus.extend(self.queue._get_rr_edus(force_flush=True))
if self._pdus:
self._last_stream_ordering = self._pdus[
-1
].internal_metadata.stream_ordering
assert self._last_stream_ordering
return self._pdus, pending_edus
async def __aexit__(self, exc_type, exc, tb):
if exc_type is not None:
# Failed to send transaction, so we bail out.
return
# Successfully sent transactions, so we remove pending PDUs from the queue
if self._pdus:
self.queue._pending_pdus = self.queue._pending_pdus[len(self._pdus) :]
# Succeeded to send the transaction so we record where we have sent up
# to in the various streams
if self._device_stream_id:
await self.queue._store.delete_device_msgs_for_remote(
self.queue._destination, self._device_stream_id
)
self.queue._last_device_stream_id = self._device_stream_id
# also mark the device updates as sent
if self._device_list_id:
logger.info(
"Marking as sent %r %r", self.queue._destination, self._device_list_id
)
await self.queue._store.mark_as_sent_devices_by_remote(
self.queue._destination, self._device_list_id
)
self.queue._last_device_list_stream_id = self._device_list_id
if self._last_stream_ordering:
# we sent some PDUs and it was successful, so update our
# last_successful_stream_ordering in the destinations table.
await self.queue._store.set_destination_last_successful_stream_ordering(
self.queue._destination, self._last_stream_ordering
)

44
synapse/federation/sender/transaction_manager.py
View File

@ -69,15 +69,12 @@ class TransactionManager:
destination: str,
pdus: List[EventBase],
edus: List[Edu],
) -> bool:
) -> None:
"""
Args:
destination: The destination to send to (e.g. 'example.org')
pdus: In-order list of PDUs to send
edus: List of EDUs to send
Returns:
True iff the transaction was successful
"""
# Make a transaction-sending opentracing span. This span follows on from
@ -96,8 +93,6 @@ class TransactionManager:
edu.strip_context()
with start_active_span_follows_from("send_transaction", span_contexts):
success = True
logger.debug("TX [%s] _attempt_new_transaction", destination)
txn_id = str(self._next_txn_id)
@ -152,44 +147,29 @@ class TransactionManager:
response = await self._transport_layer.send_transaction(
transaction, json_data_cb
)
code = 200
except HttpResponseException as e:
code = e.code
response = e.response
if e.code in (401, 404, 429) or 500 <= e.code:
logger.info(
"TX [%s] {%s} got %d response", destination, txn_id, code
)
raise e
set_tag(tags.ERROR, True)
logger.info("TX [%s] {%s} got %d response", destination, txn_id, code)
logger.info("TX [%s] {%s} got %d response", destination, txn_id, code)
raise
if code == 200:
for e_id, r in response.get("pdus", {}).items():
if "error" in r:
logger.warning(
"TX [%s] {%s} Remote returned error for %s: %s",
destination,
txn_id,
e_id,
r,
)
else:
for p in pdus:
logger.info("TX [%s] {%s} got 200 response", destination, txn_id)
for e_id, r in response.get("pdus", {}).items():
if "error" in r:
logger.warning(
"TX [%s] {%s} Failed to send event %s",
"TX [%s] {%s} Remote returned error for %s: %s",
destination,
txn_id,
p.event_id,
e_id,
r,
)
success = False
if success and pdus and destination in self._federation_metrics_domains:
if pdus and destination in self._federation_metrics_domains:
last_pdu = pdus[-1]
last_pdu_ts_metric.labels(server_name=destination).set(
last_pdu.origin_server_ts / 1000
)
set_tag(tags.ERROR, not success)
return success

10
synapse/storage/databases/main/transactions.py
View File

@ -350,11 +350,11 @@ class TransactionStore(TransactionWorkerStore):
self.db_pool.simple_upsert_many_txn(
txn,
"destination_rooms",
["destination", "room_id"],
rows,
["stream_ordering"],
[(stream_ordering,)] * len(rows),
table="destination_rooms",
key_names=("destination", "room_id"),
key_values=rows,
value_names=["stream_ordering"],
value_values=[(stream_ordering,)] * len(rows),
)
async def get_destination_last_successful_stream_ordering(

3
tests/federation/test_federation_catch_up.py
View File

@ -7,6 +7,7 @@ from synapse.federation.sender import PerDestinationQueue, TransactionManager
from synapse.federation.units import Edu
from synapse.rest import admin
from synapse.rest.client.v1 import login, room
from synapse.util.retryutils import NotRetryingDestination
from tests.test_utils import event_injection, make_awaitable
from tests.unittest import FederatingHomeserverTestCase, override_config
@ -49,7 +50,7 @@ class FederationCatchUpTestCases(FederatingHomeserverTestCase):
else:
data = json_cb()
self.failed_pdus.extend(data["pdus"])
raise IOError("Failed to connect because this is a test!")
raise NotRetryingDestination(0, 24 * 60 * 60 * 1000, txn.destination)
def get_destination_room(self, room: str, destination: str = "host2") -> dict:
"""