Scaling up to & over 40M users

Scaling Software, Scaling Data & Scaling PeopleThe Wix Experience

About Wix

Wix in Numbers

• Wix was founded in 2006• 39M registered users from most countries• Over 1,000,000 new users every month• Over 1,000,000 new websites every month• Over 150 TByte of users media files

– More than 1 billion users media files– More than 1.5 TByte uploaded files daily

• Over 300 Servers in 2+1 datacenters + Google + Amazon• Over 100,000,000 API calls a day

Flash

Wix Initial Architecture

• Tomcat, Hibernate, Custom web framework– Built for fast development– Not considering performance, scalability, fast feature rollout, testing– It reflected the fact that we didn’t really know what is our business– We know that we will need to replace it when we grow.– However, we failed to understand how difficult that can be!

• Don’t worry about ‘building it right from the start’ – you won’t• Build for gradual re-write as you learn the problems and find the right

solutions

2006 2007 2008 2009 2010 2011 2012 2013

Flash

HTML 5

Wix(Tomcat)

MySQLDB

2006 2007 2008 2009 2010 2011 2012 2013

Flash

HTML 5

Editor & Public Segments

• The Challenge - Updates to our Server imposed downtime for our customer’s websites– Any Server or Database update has the potential of bringing down all Wix sites– Is a symptom of a larger issue

• The Server served two different concerns– Wix Users editing websites– Viewing Wix Sites, the sites created by the Wix editor

• The two concerns require different SLA– Wix Sites should never ever have a downtime! – Wix Sites should work as fast as possible, always! – However, an editing system does not require this level of SLA.

Editor & Public Segments

• The two concerns evolve independently – Releases of Editing feature should have no impact on

existing Wix sites operations!• Our Solution

– Split the Server into two Segments – Public and Editor• The Public segment targets serving websites for

Wix Users– Has mostly read-only usage pattern – only updated

when a site is published– Simple publishing system– Simple and readonly means it is easier to have higher SLA and DRP– MySQL used as NoSQL – single large table with XML text fields

• The Editor segment – Exposes the Wix Editing APIs, as well as user account and galleries

management APIs.– Has different release schedule compared to the Public segment

Public(Tomcat)

Public DB

Editor(Tomcat)

Editor DB

MySQL as NoSQL

• MySQL is a damn good NoSQL engine– Our public DB was (mainly) one huge table– Queries & Updates are by primary key– Instead of relations, we use text/xml or text/json columns– No updates for Blobs – immutable data– No Transactions

• Use indirection table to blob table– Insert a new blob value, update the pointer to the new blob, async delete

• MySql auto-generated keys cause problems– Locks on key generation– Require a single instance to generate keys

• We use GUID keys– Can be generated by any client– No locks in key value generation– Enabler for Master-Master replication

Wix on Managed Hosting

2006 2007 2008 2009 2010 2011 2012 2013

Flash

HTML 5

Co-Location Managed Hosting Cloud

Own and maintain your own hardware

Lease both hardware and maintenance

Instantly lease hardware

Provisioning == buy and deliver your new server

Overnight provisioning Instant provisioningUnlimited resources

Reliable software on reliable hardware

Reliable software on reliable hardware

Reliable software on unreliable hardware

Data Centers

2006 2007 2008 2009 2010 2011 2012 2013

Flash

HTML 5

• Austin (Managed Hosting)– Our first Data Center

• Chicago (Managed Hosting)– Data DRP, then Active Active with Austin

• Amsterdam (Managed Hosting)– The idea was 3xActive– However, it failed – it is too complex to have 3 Active data centers

(3 way replication)• Amazon, Google (Cloud)

– 2nd vendor, Service Disruption DRP

Chicago AmsterdamAmazon,GoogleAustin

2006 2007 2008 2009 2010 2011 2012 2013

Flash

HTML 5

Wix Media Segment

• The Challenge – Our static storage reached over 500 GByte of small files– The “upload to app server, post process files, copy to lighttpd server, serve by

lighttpd” pattern proved inefficient, slow and error prone– Disk IO became slow and inefficient as the number of files increased– We needed a solution we can grow with –

• HTTP connections• number of files

– We needed control over caching and Http headers• We needed dynamic image manipulations

– Rebuild a few millions of media files is not simple

• Our current architecture

Prospero – Wix Media Storage

x36TM x36

TM x32TM

x36TM x36

TM x32TM

Google Cloud Storage

Austin

Chicago

get 37D815B5.jpg

First fallback

Second fallback

CDNIf not in CDN

CDN

• Use a CDN!• CDN acts as a great connection manager

– We have CDN hit ratio’s of over 99.9%• Use the “Cache Killer” pattern

– http://static.wix.com/client/css/viewer.css?v=327– http://static.wix.com/client/1.3.2/css/viewer.css– Makes flushing files from the CDN redundant– Enabler for longer caching periods

• There are many vendors– We started with 1 CDN vendor– We are now working with two CDN vendors– Different CDN vendors have advantages at different geo

• Tune HTTP Headers per CDN Vendor– CDN Vendors interpret HTTP headers differently

2006 2007 2008 2009 2010 2011 2012 2013

Flash

HTML 5

Development Velocity

• The Challenge – Our codebase became large and entangled– Feature rollout became harder over time, requiring longer and longer manual

regression– The longer the regression was, the harder is became to make “a good release” – Strange full-table scans queries generated by Hibernate, which we still have no

idea what code is responsible for…• The solution

– Mid 2010 – Wix Framework – modern base libraries– Beginning 2011 – CI / CD / TDD techniques + DevOps culture + Automated

Deployment– Mid 2011 – Scala– SOA Architecture (not WSDL) Framework

CI / CD / TDD + DevOps

Scala

People are the key

• Train the people you already have– We sent our entire QA department to learn Java– Developers learn TDD and CI/CD methodologies.

• Hiring the right people is key to success– Hire only the best developers (only seniors)– Don’t count only on the interview, you need to test actual coding– Anyone who interviews can drop a candidate– Hire people who will challenge you (no “yes man”)– Get people you can trust with “root” access to production

• Never stop hiring– If we find an excellent person we will create a position for him even if we do

not have one open.• Wix is doubling its size every year

– Yes we are currently hiring.– We’re considering to start hiring and training junior developers.

CI / CD @ Wix – Release Process

• Make an RC– Runs build, unit-tests, integration tests

CI / CD @ Wix – Release Process

• Deploy as GA– Using Chef, Noah, Artifactory– Runs Self-Tests

CI / CD @ Wix – Release Process

• Monitor– Deployment, NewRelic, App-Info, Recent Events

• Rollback