From 87b7d727605c8e122adb768b7487dfcae830593f Mon Sep 17 00:00:00 2001
From: Richard van der Hoff <richard@matrix.org>
Date: Fri, 19 Jan 2018 23:51:04 +0000
Subject: [PATCH] Add some comments about the reactor tick time metric
---
synapse/metrics/__init__.py | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/synapse/metrics/__init__.py b/synapse/metrics/__init__.py
index 2265e6e8d6..e0cfb7d08f 100644
--- a/synapse/metrics/__init__.py
+++ b/synapse/metrics/__init__.py
@@ -146,10 +146,15 @@ def runUntilCurrentTimer(func):
num_pending += 1
num_pending += len(reactor.threadCallQueue)
-
start = time.time() * 1000
ret = func(*args, **kwargs)
end = time.time() * 1000
+
+ # record the amount of wallclock time spent running pending calls.
+ # This is a proxy for the actual amount of time between reactor polls,
+ # since about 25% of time is actually spent running things triggered by
+ # I/O events, but that is harder to capture without rewriting half the
+ # reactor.
tick_time.inc_by(end - start)
pending_calls_metric.inc_by(num_pending)
--
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