Faidon Liambotis has uploaded a new change for review.
https://gerrit.wikimedia.org/r/98167
Change subject: Varnish: set hash_ignore_busy for CentralAutoLogin
......................................................................
Varnish: set hash_ignore_busy for CentralAutoLogin
Despite the English version of CentralAutoLogin being randomized across
backends, SpecialAutoLogin URLs accounted for about 23% of all 503s for
the period of Nov 26th-29th; 48% was the non-backend_random-yet German
version of CentralAutoLogin and the rest of the URLs accounted for <= 1%
each.
These URLs are, popular but their overpresentation is not explained by
access logs: for the same period account, Special:CentralAutoLogin
accounted only for 5.5% of sampled-1000s. These are the most popular
misses, though, which means that the increased failure rate is either
some underlying backend problem or increased contention on the Varnish
side.
Set hash_ignore_busy = true for English/German CentralAutoLogin and hope
that this will help with possible contention, especially in combination
with the backend_random fix.
Change-Id: I27acac463315a8b5628f65a56f1bb3be7aa10b8a
---
M templates/varnish/text-backend.inc.vcl.erb
M templates/varnish/text-frontend.inc.vcl.erb
2 files changed, 5 insertions(+), 2 deletions(-)
git pull ssh://gerrit.wikimedia.org:29418/operations/puppet
refs/changes/67/98167/1
diff --git a/templates/varnish/text-backend.inc.vcl.erb
b/templates/varnish/text-backend.inc.vcl.erb
index 9184b3f..8c051c1 100644
--- a/templates/varnish/text-backend.inc.vcl.erb
+++ b/templates/varnish/text-backend.inc.vcl.erb
@@ -38,13 +38,14 @@
<% end -%>
call pass_requests;
-<% if vcl_config.fetch("cluster_tier", "1") != "1" -%>
if (req.url ~ "^/wiki/Special:CentralAutoLogin/" ||
req.url ~
"^/w/index.php?title=Spezial:Zentrale_automatische_Anmeldung/") {
+<% if vcl_config.fetch("cluster_tier", "1") != "1" -%>
set req.backend = <%= @vcl_config.fetch("default_backend",
"backend") %>_random;
- }
<% end -%>
+ set req.hash_ignore_busy = true;
+ }
call evaluate_cookie;
diff --git a/templates/varnish/text-frontend.inc.vcl.erb
b/templates/varnish/text-frontend.inc.vcl.erb
index 39a75ed..234c714 100644
--- a/templates/varnish/text-frontend.inc.vcl.erb
+++ b/templates/varnish/text-frontend.inc.vcl.erb
@@ -71,6 +71,8 @@
if (req.url ~ "^/wiki/Special:CentralAutoLogin/" ||
req.url ~
"^/w/index.php?title=Spezial:Zentrale_automatische_Anmeldung/") {
set req.backend = backend_random;
+ set req.hash_ignore_busy = true;
+
}
/* Users that just logged out, should not get a 304 for their
--
To view, visit https://gerrit.wikimedia.org/r/98167
To unsubscribe, visit https://gerrit.wikimedia.org/r/settings
Gerrit-MessageType: newchange
Gerrit-Change-Id: I27acac463315a8b5628f65a56f1bb3be7aa10b8a
Gerrit-PatchSet: 1
Gerrit-Project: operations/puppet
Gerrit-Branch: production
Gerrit-Owner: Faidon Liambotis <fai...@wikimedia.org>
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