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Improve logging of state resolution #8371

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Sep 23, 2020
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1 change: 1 addition & 0 deletions changelog.d/8371.misc
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Improve logging of state resolution.
61 changes: 15 additions & 46 deletions synapse/state/__init__.py
Original file line number Diff line number Diff line change
Expand Up @@ -472,10 +472,9 @@ class StateResolutionHandler:
def __init__(self, hs):
self.clock = hs.get_clock()

# dict of set of event_ids -> _StateCacheEntry.
self._state_cache = None
self.resolve_linearizer = Linearizer(name="state_resolve_lock")

# dict of set of event_ids -> _StateCacheEntry.
self._state_cache = ExpiringCache(
cache_name="state_cache",
clock=self.clock,
Expand Down Expand Up @@ -519,57 +518,28 @@ async def resolve_state_groups(
Returns:
The resolved state
"""
logger.debug("resolve_state_groups state_groups %s", state_groups_ids.keys())

group_names = frozenset(state_groups_ids.keys())

with (await self.resolve_linearizer.queue(group_names)):
if self._state_cache is not None:
cache = self._state_cache.get(group_names, None)
if cache:
return cache
cache = self._state_cache.get(group_names, None)
if cache:
return cache

logger.info(
"Resolving state for %s with %d groups", room_id, len(state_groups_ids)
"Resolving state for %s with groups %s", room_id, list(group_names),
)

state_groups_histogram.observe(len(state_groups_ids))

# start by assuming we won't have any conflicted state, and build up the new
# state map by iterating through the state groups. If we discover a conflict,
# we give up and instead use `resolve_events_with_store`.
#
# XXX: is this actually worthwhile, or should we just let
# resolve_events_with_store do it?
new_state = {} # type: MutableStateMap[str]
conflicted_state = False
for st in state_groups_ids.values():
for key, e_id in st.items():
if key in new_state:
conflicted_state = True
break
new_state[key] = e_id
if conflicted_state:
break

if conflicted_state:
logger.info("Resolving conflicted state for %r", room_id)
with Measure(self.clock, "state._resolve_events"):
# resolve_events_with_store returns a StateMap, but we can
# treat it as a MutableStateMap as it is above. It isn't
# actually mutated anymore (and is frozen in
# _make_state_cache_entry below).
new_state = cast(
MutableStateMap,
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,
),
)
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,
)

# 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
Expand All @@ -579,8 +549,7 @@ async def resolve_state_groups(
with Measure(self.clock, "state.create_group_ids"):
cache = _make_state_cache_entry(new_state, state_groups_ids)

if self._state_cache is not None:
self._state_cache[group_names] = cache
self._state_cache[group_names] = cache

return cache

Expand Down