Video and slides synchronized, mp3 and slide download available at URL http://bit.ly/1fBeVJ0. Randy Shoup shares war stories from eBay and Google about performance, consistency, iterative development, and autoscaling, connecting them with experiences building KIXEYE's gaming platform. Filmed at qconsf.com. As CTO, Randy Shoup brings 25 years of engineering leadership to KIXEYE, ranging from tiny startups to Internet-scale companies. Prior to KIXEYE, he was Director of Engineering at Google, leading several teams building Google App Engine. Prior to Google, he was CTO and Co-Founder of Shopilly, an ecommerce startup, and spent 6 1/2 years as Chief Engineer and Distinguished Architect at eBay.

1. Everything I Learned About
Scaling Online Games I
Learned at Google and eBay
Randy Shoup
@randyshoup
linkedin.com/in/randyshoup

2. Watch the video with slide
synchronization on InfoQ.com!
http://www.infoq.com/presentations
/kixeye-scalability
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4. Background
CTO at KIXEYE
• Making awesome games awesomer (and scalabler
and reliabler)
Director of Engineering for Google App Engine
• World’s largest Platform-as-a-Service
Chief Engineer at eBay
• Multiple generations of eBay’s real-time search
infrastructure

5. Engineering “Fun”
Whole user / player experience
• Think holistically about the full end-to-end
experience of the user
• UX, functionality, performance, bugs, etc.
All useful metrics are *proxies* for fun
• Performance: load time, frame rate, lag
• Technology: latency, availability
• Business: acquisition, retention, monetization

6. Real-Time Strategy Games are …
Real-time
Spiky
Diverse
Constantly evolving
Constantly pushing boundaries
è Technically and operationally demanding

7. Know Your Requirements
Less is more
• More wood, fewer arrows
• Solve 100% of one problem rather than 50% of two
• Release one great feature instead of two iffy ones
Understand the requirements
•
•
•
•
e.g., Battle replay
Ephemeral combat
Immutable recording
Manageable storage footprint

8. Know Your Bottlenecks
Log everything
Monitor relentlessly
Measure bottlenecks and attack the first
• “When you solve problem one, problem two gets a
promotion”
• Theory of Constraints: attacking *any* other problem
yields no improvement
Accept that your intuition is WRONG (!)

9. Know Your Distributions
“Normal” distribution is *not* normal
• Only works for quantities physically constrained on
both sides, clustered around a mean
• E.g., adult height or weight
Leads to invalid analysis and conclusions
• Removing outliers
• Ignoring real problems
• Your (trained) intuition is WRONG (!)

10. Know Your Distributions
Exponential (“Long Tail”) distribution *much*
more common
• Income, latency, human connections, etc.
• Also easy to reason about – only single parameter
Percentiles are your best friends (!)
•
•
•
•
Reasonably characterize any distribution
Measure 90%ile, 99%ile, 99.9%ile
Focus on the real problems
Mean and Standard Deviation are useless

11. Layering and Responsibility
Multiple layers
•
•
•
•
Client
Game server
Services
Persistence
Clarify roles and responsibilities
• Client- vs. server-authoritative
• Google service layering (+)

12. Distribution of Data / Work
Load-balancing (for stateless work)
• Web servers, proxies
• Most services
Sharding (for stateful work)
•
•
•
•
Combat servers
Matchmaking
Leaderboards
Databases

13. Services
Simple, well-defined interface
Single-purpose
Modular and independent
Small team
Autonomy and responsibility

14. Component Isolation
Combat server for TOME
• Highly “twitchy” real-time MOBA combat
• Very latency-sensitive
Real-time interactions isolated to a single,
ephemeral component
• No coordination with any central service
Highly dynamic load distribution
• Router assigns battle to least-loaded server
• Requires latency-fairness between players

15. Asynchrony: Do Work Up Front
Custom asset pipeline
• Spriting, compression, etc
Pre-render “movies” instead of real-time particle
effects
Tons of caching

16. Asynchrony: Client Liveness
Client continues seamlessly if disconnected
• Gameplay more important than immediate
synchronization
Event loop for rendering
• Keep up with the frame rate (!)
Default to background processing
• Refresh assets
• Save client state

17. Asynchrony: Reactive Server
Minimize request latency
• Respond as rapidly as possible to client
• Queue events / messages for complex work
• Service interactions via reliable events
Functional Reactive programming
• Heavy use of Scala and Akka
• Never block (!)
• eBay, Google programming models (-)

18. Small, Independent Teams
Studio System
• Full-stack, independent game teams
• Near-complete autonomy on technology choices,
development processes
Vendor-customer discipline
• Google service teams (+)
Reduces contention and coherence

19. Hire and Retain Top People
Hire ‘A’ Players
• Difference between top and bottom performers is
not 1.5x; it’s 10x (!)
• (+) Google hiring process
Virtuous Cycle
• A players bring A players
• B players bring C players
• Constantly raise the bar
Reduces contention and coherence

20. Play to People’s Strengths
People are not cogs, not fungible
• (-) eBay “Train seats”
• Destroyed incentives, personal pride, long-term
ownership
Align work with skills and passion
• Symphony instead of Factory (!)
• Skills in Flash, Scala, etc.
• Build customizability for target developer, not
builder (DSL >> code)

21. Small Details Matter
In the very large, the very small matters a *lot*
• Subatomic physics and cosmology
• eBay and variable-byte encoding (+)
• GAE and memcache slab memory allocation (+)
Discipline is *which* details matter
• Combat server and memory contention
• 40% improvement from six characters …
• “const ”

22. Join us!
www.kixeye.com [jobs]

23. Watch the video with slide synchronization on
InfoQ.com!
http://www.infoq.com/presentations/kixeyescalability