I think we're going to need something a little more specific to go on. That is a mile of changes all at once.
Finding a single request that should be cached, but isn't and producing the varnish log for that request will probably help illuminate what's going on. On Wed, Dec 7, 2016 at 4:22 PM, Justin Lloyd <[email protected]> wrote: > Hello, > > > > I use Varnish on four load-balanced web servers running Apache with > several virtual hosts providing MediaWiki wikis. Last week I upgraded the > web servers to support upgrading MediaWiki from 1.26 to 1.27 due to PHP > requirements. This meant upgrading (reinstalling) Ubuntu 12.04 to 16.04, > meaning I went from PHP 5.3 to 7, Apache 2.4 + mod_php to Apache 2.4 + > PHP-FPM, and Varnish 3 to 4. > > > > For the upgrade from Varnish 3 to 4, I adapted my VCL code > <https://gist.github.com/Calygos/105957a997ea3bde6b8257a1f34bbd20> > accordingly, based on Mediawiki Varnish sample code > <https://www.mediawiki.org/wiki/Manual:Varnish_caching>, but for reasons > I don’t understand, my Varnish hit ratio dropped from around 86% to > ~20-37%. This picture <http://imgur.com/jX4iu6s> shows a graph of the > last 10 days hit ratio calculations for the four web servers. The graph is > calculated using metrics from the Collectd Varnish plugin as (conns - > bereqs / conns), i.e.: > > > > asPercent( > > diffSeries( > > linux.*hostname*.varnish-default-connections.connections-received, > > linux.*hostname*.varnish-default-backend.http_requests-requests > > ), > > linux.*hostname*.varnish-default-connections.connections-received > > ) > > > > I’ve also tried the Varnish hit and miss metrics but those give similar > results. So I’m not sure what changed to give such a poor hit ratio, > despite otherwise good performance on large, busy wikis. It’s possible it > could be something in MediaWiki’s cookie and/or session handling and I’ve > been investigating that possibility as well, but I figured this would be a > good place to ask, too. > > > > Thanks, > > Justin > > > > _______________________________________________ > varnish-misc mailing list > [email protected] > https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc >
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