Merge pull request #3956 from matrix-org/rav/fix_expiring_cache_len

Fix ExpiringCache.__len__ to be accurate
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Richard van der Hoff 2018-09-26 13:10:13 +01:00 committed by GitHub
commit 4e8276a34a
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3 changed files with 25 additions and 20 deletions

1
changelog.d/3956.bugfix Normal file
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@ -0,0 +1 @@
Fix exceptions from metrics handler

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@ -13,6 +13,7 @@
# See the License for the specific language governing permissions and # See the License for the specific language governing permissions and
# limitations under the License. # limitations under the License.
import logging
import os import os
import six import six
@ -20,6 +21,8 @@ from six.moves import intern
from prometheus_client.core import REGISTRY, Gauge, GaugeMetricFamily from prometheus_client.core import REGISTRY, Gauge, GaugeMetricFamily
logger = logging.getLogger(__name__)
CACHE_SIZE_FACTOR = float(os.environ.get("SYNAPSE_CACHE_FACTOR", 0.5)) CACHE_SIZE_FACTOR = float(os.environ.get("SYNAPSE_CACHE_FACTOR", 0.5))
@ -76,6 +79,7 @@ def register_cache(cache_type, cache_name, cache):
return [] return []
def collect(self): def collect(self):
try:
if cache_type == "response_cache": if cache_type == "response_cache":
response_cache_size.labels(cache_name).set(len(cache)) response_cache_size.labels(cache_name).set(len(cache))
response_cache_hits.labels(cache_name).set(self.hits) response_cache_hits.labels(cache_name).set(self.hits)
@ -86,6 +90,9 @@ def register_cache(cache_type, cache_name, cache):
cache_hits.labels(cache_name).set(self.hits) cache_hits.labels(cache_name).set(self.hits)
cache_evicted.labels(cache_name).set(self.evicted_size) cache_evicted.labels(cache_name).set(self.evicted_size)
cache_total.labels(cache_name).set(self.hits + self.misses) cache_total.labels(cache_name).set(self.hits + self.misses)
except Exception as e:
logger.warn("Error calculating metrics for %s: %s", cache_name, e)
raise
yield GaugeMetricFamily("__unused", "") yield GaugeMetricFamily("__unused", "")

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@ -16,6 +16,8 @@
import logging import logging
from collections import OrderedDict from collections import OrderedDict
from six import itervalues
from synapse.metrics.background_process_metrics import run_as_background_process from synapse.metrics.background_process_metrics import run_as_background_process
from synapse.util.caches import register_cache from synapse.util.caches import register_cache
@ -54,8 +56,6 @@ class ExpiringCache(object):
self.iterable = iterable self.iterable = iterable
self._size_estimate = 0
self.metrics = register_cache("expiring", cache_name, self) self.metrics = register_cache("expiring", cache_name, self)
if not self._expiry_ms: if not self._expiry_ms:
@ -74,16 +74,11 @@ class ExpiringCache(object):
now = self._clock.time_msec() now = self._clock.time_msec()
self._cache[key] = _CacheEntry(now, value) self._cache[key] = _CacheEntry(now, value)
if self.iterable:
self._size_estimate += len(value)
# Evict if there are now too many items # Evict if there are now too many items
while self._max_len and len(self) > self._max_len: while self._max_len and len(self) > self._max_len:
_key, value = self._cache.popitem(last=False) _key, value = self._cache.popitem(last=False)
if self.iterable: if self.iterable:
removed_len = len(value.value) self.metrics.inc_evictions(len(value.value))
self.metrics.inc_evictions(removed_len)
self._size_estimate -= removed_len
else: else:
self.metrics.inc_evictions() self.metrics.inc_evictions()
@ -134,7 +129,9 @@ class ExpiringCache(object):
for k in keys_to_delete: for k in keys_to_delete:
value = self._cache.pop(k) value = self._cache.pop(k)
if self.iterable: if self.iterable:
self._size_estimate -= len(value.value) self.metrics.inc_evictions(len(value.value))
else:
self.metrics.inc_evictions()
logger.debug( logger.debug(
"[%s] _prune_cache before: %d, after len: %d", "[%s] _prune_cache before: %d, after len: %d",
@ -143,7 +140,7 @@ class ExpiringCache(object):
def __len__(self): def __len__(self):
if self.iterable: if self.iterable:
return self._size_estimate return sum(len(entry.value) for entry in itervalues(self._cache))
else: else:
return len(self._cache) return len(self._cache)