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Merge pull request #8420 from matrix-org/rav/state_res_stats

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Report metrics on expensive rooms for state res
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Richard van der Hoff 2020-09-30 10:37:52 +01:00 committed by GitHub
commit c429dfc300
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4 changed files with 200 additions and 80 deletions
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1
changelog.d/8420.feature Normal file
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@ -0,0 +1 @@
Add experimental reporting of metrics on expensive rooms for state-resolution.

13
synapse/handlers/federation.py
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@ -21,7 +21,7 @@ import itertools
import logging
from collections.abc import Container
from http import HTTPStatus
from typing import Dict, Iterable, List, Optional, Sequence, Tuple, Union
from typing import TYPE_CHECKING, Dict, Iterable, List, Optional, Sequence, Tuple, Union
import attr
from signedjson.key import decode_verify_key_bytes
@ -69,7 +69,7 @@ from synapse.replication.http.federation import (
ReplicationFederationSendEventsRestServlet,
ReplicationStoreRoomOnInviteRestServlet,
)
from synapse.state import StateResolutionStore, resolve_events_with_store
from synapse.state import StateResolutionStore
from synapse.storage.databases.main.events_worker import EventRedactBehaviour
from synapse.types import (
JsonDict,
@ -85,6 +85,9 @@ from synapse.util.retryutils import NotRetryingDestination
from synapse.util.stringutils import shortstr
from synapse.visibility import filter_events_for_server
if TYPE_CHECKING:
from synapse.server import HomeServer
logger = logging.getLogger(__name__)
@ -116,7 +119,7 @@ class FederationHandler(BaseHandler):
rooms.
"""
def __init__(self, hs):
def __init__(self, hs: "HomeServer"):
super().__init__(hs)
self.hs = hs
@ -126,6 +129,7 @@ class FederationHandler(BaseHandler):
self.state_store = self.storage.state
self.federation_client = hs.get_federation_client()
self.state_handler = hs.get_state_handler()
self._state_resolution_handler = hs.get_state_resolution_handler()
self.server_name = hs.hostname
self.keyring = hs.get_keyring()
self.action_generator = hs.get_action_generator()
@ -381,8 +385,7 @@ class FederationHandler(BaseHandler):
event_map[x.event_id] = x
room_version = await self.store.get_room_version_id(room_id)
state_map = await resolve_events_with_store(
self.clock,
state_map = await self._state_resolution_handler.resolve_events_with_store(
room_id,
room_version,
state_maps,

233
synapse/state/__init__.py
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@ -13,42 +13,46 @@
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import heapq
import logging
from collections import namedtuple
from collections import defaultdict, namedtuple
from typing import (
Any,
Awaitable,
Callable,
DefaultDict,
Dict,
Iterable,
List,
Optional,
Sequence,
Set,
Tuple,
Union,
overload,
)
import attr
from frozendict import frozendict
from prometheus_client import Histogram
from prometheus_client import Counter, Histogram
from typing_extensions import Literal
from synapse.api.constants import EventTypes
from synapse.api.room_versions import KNOWN_ROOM_VERSIONS, StateResolutionVersions
from synapse.events import EventBase
from synapse.events.snapshot import EventContext
from synapse.logging.context import ContextResourceUsage
from synapse.logging.utils import log_function
from synapse.state import v1, v2
from synapse.storage.databases.main.events_worker import EventRedactBehaviour
from synapse.storage.roommember import ProfileInfo
from synapse.types import Collection, StateMap
from synapse.util import Clock
from synapse.util.async_helpers import Linearizer
from synapse.util.caches.expiringcache import ExpiringCache
from synapse.util.metrics import Measure, measure_func
logger = logging.getLogger(__name__)
metrics_logger = logging.getLogger("synapse.state.metrics")
# Metrics for number of state groups involved in a resolution.
state_groups_histogram = Histogram(
@ -448,19 +452,44 @@ class StateHandler:
state_map = {ev.event_id: ev for st in state_sets for ev in st}
with Measure(self.clock, "state._resolve_events"):
new_state = await resolve_events_with_store(
self.clock,
event.room_id,
room_version,
state_set_ids,
event_map=state_map,
state_res_store=StateResolutionStore(self.store),
)
new_state = await self._state_resolution_handler.resolve_events_with_store(
event.room_id,
room_version,
state_set_ids,
event_map=state_map,
state_res_store=StateResolutionStore(self.store),
)
return {key: state_map[ev_id] for key, ev_id in new_state.items()}
@attr.s(slots=True)
class _StateResMetrics:
"""Keeps track of some usage metrics about state res."""
# System and User CPU time, in seconds
cpu_time = attr.ib(type=float, default=0.0)
# time spent on database transactions (excluding scheduling time). This roughly
# corresponds to the amount of work done on the db server, excluding event fetches.
db_time = attr.ib(type=float, default=0.0)
# number of events fetched from the db.
db_events = attr.ib(type=int, default=0)
_biggest_room_by_cpu_counter = Counter(
"synapse_state_res_cpu_for_biggest_room_seconds",
"CPU time spent performing state resolution for the single most expensive "
"room for state resolution",
)
_biggest_room_by_db_counter = Counter(
"synapse_state_res_db_for_biggest_room_seconds",
"Database time spent performing state resolution for the single most "
"expensive room for state resolution",
)
class StateResolutionHandler:
"""Responsible for doing state conflict resolution.
@ -483,6 +512,17 @@ class StateResolutionHandler:
reset_expiry_on_get=True,
)
#
# stuff for tracking time spent on state-res by room
#
# tracks the amount of work done on state res per room
self._state_res_metrics = defaultdict(
_StateResMetrics
) # type: DefaultDict[str, _StateResMetrics]
self.clock.looping_call(self._report_metrics, 120 * 1000)
@log_function
async def resolve_state_groups(
self,
@ -530,15 +570,13 @@ class StateResolutionHandler:
state_groups_histogram.observe(len(state_groups_ids))
with Measure(self.clock, "state._resolve_events"):
new_state = await resolve_events_with_store(
self.clock,
room_id,
room_version,
list(state_groups_ids.values()),
event_map=event_map,
state_res_store=state_res_store,
)
new_state = await self.resolve_events_with_store(
room_id,
room_version,
list(state_groups_ids.values()),
event_map=event_map,
state_res_store=state_res_store,
)
# if the new state matches any of the input state groups, we can
# use that state group again. Otherwise we will generate a state_id
@ -552,6 +590,114 @@ class StateResolutionHandler:
return cache
async def resolve_events_with_store(
self,
room_id: str,
room_version: str,
state_sets: Sequence[StateMap[str]],
event_map: Optional[Dict[str, EventBase]],
state_res_store: "StateResolutionStore",
) -> StateMap[str]:
"""
Args:
room_id: the room we are working in
room_version: Version of the room
state_sets: List of dicts of (type, state_key) -> event_id,
which are the different state groups to resolve.
event_map:
a dict from event_id to event, for any events that we happen to
have in flight (eg, those currently being persisted). This will be
used as a starting point fof finding the state we need; any missing
events will be requested via state_map_factory.
If None, all events will be fetched via state_res_store.
state_res_store: a place to fetch events from
Returns:
a map from (type, state_key) to event_id.
"""
try:
with Measure(self.clock, "state._resolve_events") as m:
v = KNOWN_ROOM_VERSIONS[room_version]
if v.state_res == StateResolutionVersions.V1:
return await v1.resolve_events_with_store(
room_id, state_sets, event_map, state_res_store.get_events
)
else:
return await v2.resolve_events_with_store(
self.clock,
room_id,
room_version,
state_sets,
event_map,
state_res_store,
)
finally:
self._record_state_res_metrics(room_id, m.get_resource_usage())
def _record_state_res_metrics(self, room_id: str, rusage: ContextResourceUsage):
room_metrics = self._state_res_metrics[room_id]
room_metrics.cpu_time += rusage.ru_utime + rusage.ru_stime
room_metrics.db_time += rusage.db_txn_duration_sec
room_metrics.db_events += rusage.evt_db_fetch_count
def _report_metrics(self):
if not self._state_res_metrics:
# no state res has happened since the last iteration: don't bother logging.
return
self._report_biggest(
lambda i: i.cpu_time, "CPU time", _biggest_room_by_cpu_counter,
)
self._report_biggest(
lambda i: i.db_time, "DB time", _biggest_room_by_db_counter,
)
self._state_res_metrics.clear()
def _report_biggest(
self,
extract_key: Callable[[_StateResMetrics], Any],
metric_name: str,
prometheus_counter_metric: Counter,
) -> None:
"""Report metrics on the biggest rooms for state res
Args:
extract_key: a callable which, given a _StateResMetrics, extracts a single
metric to sort by.
metric_name: the name of the metric we have extracted, for the log line
prometheus_counter_metric: a prometheus metric recording the sum of the
the extracted metric
"""
n_to_log = 10
if not metrics_logger.isEnabledFor(logging.DEBUG):
# only need the most expensive if we don't have debug logging, which
# allows nlargest() to degrade to max()
n_to_log = 1
items = self._state_res_metrics.items()
# log the N biggest rooms
biggest = heapq.nlargest(
n_to_log, items, key=lambda i: extract_key(i[1])
) # type: List[Tuple[str, _StateResMetrics]]
metrics_logger.debug(
"%i biggest rooms for state-res by %s: %s",
len(biggest),
metric_name,
["%s (%gs)" % (r, extract_key(m)) for (r, m) in biggest],
)
# report info on the single biggest to prometheus
_, biggest_metrics = biggest[0]
prometheus_counter_metric.inc(extract_key(biggest_metrics))
def _make_state_cache_entry(
new_state: StateMap[str], state_groups_ids: Dict[int, StateMap[str]]
@ -605,47 +751,6 @@ def _make_state_cache_entry(
)
def resolve_events_with_store(
clock: Clock,
room_id: str,
room_version: str,
state_sets: Sequence[StateMap[str]],
event_map: Optional[Dict[str, EventBase]],
state_res_store: "StateResolutionStore",
) -> Awaitable[StateMap[str]]:
"""
Args:
room_id: the room we are working in
room_version: Version of the room
state_sets: List of dicts of (type, state_key) -> event_id,
which are the different state groups to resolve.
event_map:
a dict from event_id to event, for any events that we happen to
have in flight (eg, those currently being persisted). This will be
used as a starting point fof finding the state we need; any missing
events will be requested via state_map_factory.
If None, all events will be fetched via state_res_store.
state_res_store: a place to fetch events from
Returns:
a map from (type, state_key) to event_id.
"""
v = KNOWN_ROOM_VERSIONS[room_version]
if v.state_res == StateResolutionVersions.V1:
return v1.resolve_events_with_store(
room_id, state_sets, event_map, state_res_store.get_events
)
else:
return v2.resolve_events_with_store(
clock, room_id, room_version, state_sets, event_map, state_res_store
)
@attr.s(slots=True)
class StateResolutionStore:
"""Interface that allows state resolution algorithms to access the database

33
synapse/util/metrics.py
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@ -19,7 +19,11 @@ from typing import Any, Callable, Optional, TypeVar, cast
from prometheus_client import Counter
from synapse.logging.context import LoggingContext, current_context
from synapse.logging.context import (
ContextResourceUsage,
LoggingContext,
current_context,
)
from synapse.metrics import InFlightGauge
logger = logging.getLogger(__name__)
@ -104,27 +108,27 @@ class Measure:
def __init__(self, clock, name):
self.clock = clock
self.name = name
self._logging_context = None
self.start = None
def __enter__(self):
if self._logging_context:
raise RuntimeError("Measure() objects cannot be re-used")
self.start = self.clock.time()
parent_context = current_context()
self._logging_context = LoggingContext(
"Measure[%s]" % (self.name,), parent_context
)
self.start = None
def __enter__(self) -> "Measure":
if self.start is not None:
raise RuntimeError("Measure() objects cannot be re-used")
self.start = self.clock.time()
self._logging_context.__enter__()
in_flight.register((self.name,), self._update_in_flight)
return self
def __exit__(self, exc_type, exc_val, exc_tb):
if not self._logging_context:
if self.start is None:
raise RuntimeError("Measure() block exited without being entered")
duration = self.clock.time() - self.start
usage = self._logging_context.get_resource_usage()
usage = self.get_resource_usage()
in_flight.unregister((self.name,), self._update_in_flight)
self._logging_context.__exit__(exc_type, exc_val, exc_tb)
@ -140,6 +144,13 @@ class Measure:
except ValueError:
logger.warning("Failed to save metrics! Usage: %s", usage)
def get_resource_usage(self) -> ContextResourceUsage:
"""Get the resources used within this Measure block
If the Measure block is still active, returns the resource usage so far.
"""
return self._logging_context.get_resource_usage()
def _update_in_flight(self, metrics):
"""Gets called when processing in flight metrics
"""