BBlack has submitted this change and it was merged. Change subject: Varnish: stream all pass traffic ......................................................................
Varnish: stream all pass traffic The default in varnish 3 is "do_stream = false", and nothing turns it on other than explicit VCL. Naively, one would assume that streaming is always better than not-streaming, but there are complications from Varnish: Whether to turn it on for cache miss fetches is a tradeoff that involves complex questions: the upside is immediate streaming to the client instead of buffering the whole response first, but the downside is that the cache object fills into varnish at the rate the *client* is accepting the stream, and all other fetches from other faster clients will stall out on that busy object (unless hash_ignore_busy, which is yet another tradeoff decision). However, for 'pass' traffic (from return pass or hit-for-pass), turning on do_stream has no downsides, as pass traffic isn't sharing a potentially-busy object with another client. So this should be a performance win for pass objects (especially large ones) without any real downside. Change-Id: I3fd4d56aeb4c297b4b2e2f36d7e54a28e2a11204 Ref: http://info.varnish-software.com/blog/streaming-varnish-30 --- M modules/varnish/templates/vcl/wikimedia-common.inc.vcl.erb 1 file changed, 6 insertions(+), 0 deletions(-) Approvals: BBlack: Looks good to me, approved jenkins-bot: Verified diff --git a/modules/varnish/templates/vcl/wikimedia-common.inc.vcl.erb b/modules/varnish/templates/vcl/wikimedia-common.inc.vcl.erb index fdd7a28..bd6da1c7 100644 --- a/modules/varnish/templates/vcl/wikimedia-common.inc.vcl.erb +++ b/modules/varnish/templates/vcl/wikimedia-common.inc.vcl.erb @@ -234,9 +234,15 @@ } else { set req.http.X-CDIS = "pass"; } + + set req.http.X-Pass-Stream = 1; } sub wm_common_fetch { + if (req.http.X-Pass-Stream) { + set beresp.do_stream = true; + } + <% if @vcl_config.fetch("ttl_fixed", false) -%> // Fixed TTL (rare/questionable, only used on upload backend right now) // Note the ttl_cap comes after this and takes precedence! -- To view, visit https://gerrit.wikimedia.org/r/276475 To unsubscribe, visit https://gerrit.wikimedia.org/r/settings Gerrit-MessageType: merged Gerrit-Change-Id: I3fd4d56aeb4c297b4b2e2f36d7e54a28e2a11204 Gerrit-PatchSet: 2 Gerrit-Project: operations/puppet Gerrit-Branch: production Gerrit-Owner: BBlack <bbl...@wikimedia.org> Gerrit-Reviewer: BBlack <bbl...@wikimedia.org> Gerrit-Reviewer: Ema <e...@wikimedia.org> Gerrit-Reviewer: Faidon Liambotis <fai...@wikimedia.org> Gerrit-Reviewer: jenkins-bot <> _______________________________________________ MediaWiki-commits mailing list MediaWiki-commits@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/mediawiki-commits
