From 0d87c6bd121d043d5474cc20e352794ff8cf5625 Mon Sep 17 00:00:00 2001
From: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>
Date: Tue, 6 Apr 2021 16:32:04 +0100
Subject: [PATCH] Don't report anything from GaugeBucketCollector metrics until
data is present (#8926)
This PR modifies `GaugeBucketCollector` to only report data once it has been updated, rather than initially reporting a value of 0. Fixes zero values being reported for some metrics on startup until a background job to update the metric's value runs later.
---
changelog.d/8926.bugfix | 1 +
synapse/metrics/__init__.py | 16 +++++++++++++---
2 files changed, 14 insertions(+), 3 deletions(-)
create mode 100644 changelog.d/8926.bugfix
diff --git a/changelog.d/8926.bugfix b/changelog.d/8926.bugfix
new file mode 100644
index 0000000000..aad7bd83ce
--- /dev/null
+++ b/changelog.d/8926.bugfix
@@ -0,0 +1 @@
+Prevent `synapse_forward_extremities` and `synapse_excess_extremity_events` Prometheus metrics from initially reporting zero-values after startup.
diff --git a/synapse/metrics/__init__.py b/synapse/metrics/__init__.py
index 3b499efc07..13a5bc4558 100644
--- a/synapse/metrics/__init__.py
+++ b/synapse/metrics/__init__.py
@@ -214,7 +214,12 @@ class GaugeBucketCollector:
Prometheus, and optimise for that case.
"""
- __slots__ = ("_name", "_documentation", "_bucket_bounds", "_metric")
+ __slots__ = (
+ "_name",
+ "_documentation",
+ "_bucket_bounds",
+ "_metric",
+ )
def __init__(
self,
@@ -242,11 +247,16 @@ class GaugeBucketCollector:
if self._bucket_bounds[-1] != float("inf"):
self._bucket_bounds.append(float("inf"))
- self._metric = self._values_to_metric([])
+ # We initially set this to None. We won't report metrics until
+ # this has been initialised after a successful data update
+ self._metric = None # type: Optional[GaugeHistogramMetricFamily]
+
registry.register(self)
def collect(self):
- yield self._metric
+ # Don't report metrics unless we've already collected some data
+ if self._metric is not None:
+ yield self._metric
def update_data(self, values: Iterable[float]):
"""Update the data to be reported by the metric
--
GitLab