From 130df8fb01bce1bf244940131d85d1c1a54ed5ef Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Fri, 6 Mar 2015 10:25:36 +0000
Subject: [PATCH] Add some randomness to the user specified timeout on event
streams to mitigate against thundering herds problems
---
synapse/handlers/events.py | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/synapse/handlers/events.py b/synapse/handlers/events.py
index 8d5f5c8499..d3297b7292 100644
--- a/synapse/handlers/events.py
+++ b/synapse/handlers/events.py
@@ -23,6 +23,7 @@ from synapse.events.utils import serialize_event
from ._base import BaseHandler
import logging
+import random
logger = logging.getLogger(__name__)
@@ -72,6 +73,14 @@ class EventStreamHandler(BaseHandler):
rm_handler = self.hs.get_handlers().room_member_handler
room_ids = yield rm_handler.get_rooms_for_user(auth_user)
+ if timeout:
+ # If they've set a timeout set a minimum limit.
+ timeout = max(timeout, 500)
+
+ # Add some randomness to this value to try and mitigate against
+ # thundering herds on restart.
+ timeout = random.randint(int(timeout*0.9), int(timeout*1.1))
+
with PreserveLoggingContext():
events, tokens = yield self.notifier.get_events_for(
auth_user, room_ids, pagin_config, timeout
--
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