diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index a1acacbde9..7e69cf55fb 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -22,6 +22,8 @@ from collections import namedtuple
import six
from six import itervalues, string_types
+from prometheus_client import Gauge
+
from twisted.internet import defer
from synapse.logging.context import make_deferred_yieldable, preserve_fn
@@ -37,6 +39,12 @@ from . import register_cache
logger = logging.getLogger(__name__)
+cache_pending_metric = Gauge(
+ "synapse_util_caches_cache_pending",
+ "Number of lookups currently pending for this cache",
+ ["name"],
+)
+
_CacheSentinel = object()
@@ -82,11 +90,19 @@ class Cache(object):
self.name = name
self.keylen = keylen
self.thread = None
- self.metrics = register_cache("cache", name, self.cache)
+ self.metrics = register_cache(
+ "cache",
+ name,
+ self.cache,
+ collect_callback=self._metrics_collection_callback,
+ )
def _on_evicted(self, evicted_count):
self.metrics.inc_evictions(evicted_count)
+ def _metrics_collection_callback(self):
+ cache_pending_metric.labels(self.name).set(len(self._pending_deferred_cache))
+
def check_thread(self):
expected_thread = self.thread
if expected_thread is None:
|
