Asynchronous Personalization at Groupon - JSConf 2011

asynchronous personalization [and CDNs and A/B testing and stuff] Jon Pliske Performance Engineering, Groupon @jonpliske jpliske@groupon.com

You might know me from this leaked photo on TechCrunch Jon PliskePerformance Engineering, Groupon @jonpliske jpliske@groupon.com

overview background CDN caching async personalization a/b/multivariate testing /w finch.js

performance anxiety big rails app performance issues big team === development process hurdles big traffic drinking problems Reaching limit of Rails caching Low-level optimizations too "incremental" Rewriting SQL is boring Improve platform architecture

super bowl partyprelude:jan 1. "btw we have pre/post super bowl commercials"jan 15. "scored an in-game spot, we good?"feb 15. offend the world"spike mode": CDN cache it all! disable login offload geocoding/subscriptions/orders to EC2 limited functionality === unhappy users

pics or it didnt happen

CDNs are neatpros conslow latency dynamic content"edge side nodes" personalizationhigh capacity complexitystatic content overkill? specifically: personalized content (login menu, deals) analytics tracking a/b testing Rails developers

async personalizationtarget: deal/division pages (> 50% of traffic)approach:1. cache "anonymous" page in CDN2. hide stuff3. make AJAX request for personalized data/content4. show stuffSee Chris Williams "Rails’ Best Caching Method is JavaScript"from GoRuCo 2010

obligatory omnigraffle diagram

"Anonymous" userbefore:initial page response time: 0.8 secrendering time (e.g. loading css/js/images): 1 sectotal: 1.8 secafter:initial page response time: 0.1 secrendering time: 1 sectotal: 1.1 seconly a little bit faster...(1.1 vs 1.8 sec)basically no server load => huge capacity increase!

Logged-in User / Subscriberbefore:initial page response time: 3 secrendering time (e.g. loading js/css/images): 1 sectotal time: 4 secafter:initial page response time: 0.1 secrendering time (include AJAX call:1 sec): 1 sectotal time: 1.1 secCapacity constant: AJAX call still needs to hit Rails300% faster!

[wait for applause]

development implicationsless Rails, more JS1 user !== 1 (Rails) requestgoodbye:current_usersessioncookiestesting

onCurrentUserReady(callback)callback when personalize API returns (or callback immediatelyfor anonymous user)before:- if logged_in? do stuff for logged-in user- else do stuff for anonymous userafter:Groupon.onCurrentUserReady(function(){ if (Groupon.currentUser.isAuthenticated) { do stuff for logged-in user } else { do stuff for anonymous user }});

analyticsProblem: Request loggingSolution: Tracking pixel (hit Nginx only, not Rails)Problem: Content changesSolution: Dynamic tracking pixelProblem: Tracking params (e.g. utm params, affiliate id, etc...)Solution: Store in cookie; append params to API request

a/b testing with FinchProblem: Finch uses view/controller logic to choose and trackexperiments and variants- experiment Two vs. Three Step Subscription do |e| - e.variant Original do %h1 Fill out this form to subscribe now - e.variant Two Step do %h4 Follow these two steps to subscribe - e.variant Three Step do %p Subscribe now - it only takes a few seconds

Finch.jsFinch.Experiments.DelayedJSExperiment = { defer: function() { var experiment = this; FinchDemo.onCurrentUserReady(function() { experiment.deferedRun(this); }); }, before: function() { $(#delayed).hide(); }, after: function() { $(#delayed).show(); }, variants: { original: function() { $(#delayed .original).show(); }, alternate: function() { $(#delayed .alternate).show();}, }};$(function() { Finch.run(window);});

Finch.js based on Googles "Overlapping Experiment Infrastructure" written in coffee-script open source soon-ishly ~ 15k of JS doesnt handle tracking/analytics/analysis side of testing (yet?)

the futurepure-JSON API requestsclient-side rendering (/w mustache.js)HTML5 storagedecouple from Railsdevelopment practices:front/back-end integrationbetter testingbetter monitoring

Thank you! @jonpliskejpliske@groupon.comgroupon.com/techjobs

Asynchronous Personalization at Groupon - JSConf 2011

by jonpliske on May 03, 2011

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Asynchronous Personalization at Groupon - JSConf 2011 Presentation Transcript