1. F#
in the Cloud and at Scale
Yan Cui (@theburningmonk)
Image by Mike Rohde

2. Who is Gamesys?
• Founded in 2001
• #1 in the UK
• Handle $5 Billion in turnover annually
• First company to launch real money gaming on Facebook
• Employ 1,000 globally

6. Running in the Cloud, at Scale
• 1 Million DAU
• 250 Million requests/day
• 7 Billion rows of analytics events/month
• 2 TB of analytics data/month

7. Running in the Cloud, at Scale
• 100% cloud hosted
• AWS for Game services
• Google App Engine for back-office services
• NoSQL databases
– DynamoDB, CouchBase, Redis, Neo4j, ...
• Google BigQuery for analytics

8. What is the Cloud?
Cloud computing is an expression used to describe a
variety of computing concepts that involve a large
number of computers connected through a real-time
communication network such as the Internet....
Such virtual servers do not physically exist and can
therefore be moved around and scaled up (or down)
on the fly without affecting the end user arguably, rather like a cloud.
- Wikipedia

9. What is the Cloud?
IaaS
PaaS
SaaS
VMs, load
balancers,
storage, ...
Runtime, databa
se, web
servers, ...
Virtual
desktop, games,
emails, ...

10. Why the Cloud?
• Trade capital cost with operating cost
• Lower operating cost
• Elastic scaling
• Speed and agility
• Focus on what differentiates your product
• Global infrastructure for your global audience

11. Why the Cloud - Scalability
• Scale up
• Scale out
• Scale everything!
– Your architecture is as scalable as its least scalable part
• Scalability != simple choice of language/framework

12. Travel, Collect, Craft!

13. Trap Monsters

15. Stateful Server
EC2
Elastic Load Balancer
CloudFront
Server A
Server B
...
Auto scaling Group
S3

16. Stateful Server
• Need to ensure Server affinity
– All calls need to be routed to the affined server
• Need to balance load
– Session lengths vary greatly
– Some players are more active than others
– Need to avoid hot spots
• Need to avoid players hogging a server
– Need to be able to scale down!

17. Stateful Server
• Persist player state after short inactivity
• Move player to another server after persistence

18. Why Stateful Server?
• 500% efficiency increase
• 60% reduction in avg latency
• Fewer game servers
• No CouchBase cluster
• Huge saving on cost

19. The Actor Model
An actor is the fundamental unit of computation which
embodies the 3 things
• Processing
• Storage
• Communication
that are essential to computation.
-Carl Hewitt*
* http://bit.ly/HoNHbG

20. The Actor Model
• Everything is an actor
• An actor has a mailbox
• When an actor receives a message it can:
– Create new actors
– Send messages to actors it has addresses for
– Designate how to handle the next message it receives

21. Stateful Server
• Gatekeeper
– Manages the local list of active workers
– Spawns new workers
• Worker
– Manages the states for a player
– Optimistic locking
– Persist state after period of inactivity

22. Stateful Server
Asynchronous
Player B
Request Handlers
Player A
Gatekeeper
S3
Worker C
Worker B
Game Server

23. Stateful Server
Asynchronous
Worker A
Player A
Request Handlers
Player B
ok
Gatekeeper
S3
Worker C
Worker B
Game Server

24. Stateful Server
Asynchronous
Worker A
Player B
Request Handlers
Player A
Gatekeeper
S3
Worker C
Worker B
Game Server

25. Stateful Server
Asynchronous
Worker A
Player B
Request Handlers
Player A
Gatekeeper
Worker C
Game Server
S3

26. Stateful Server
Asynchronous
Worker A
Player B
Request Handlers
Player A
Gatekeeper
Worker C
Game Server
S3

28. MailboxProcessor<Message>

29. Async<Message option>

30. switch state

33. Why F#?
• Time to Market
• Efficiency
• Correctness
• Complexity

34. Why F#?
• Agents
– No locks
– Asynchronous message passing
– Each actor is self-contained and easier to reason with
• Pattern matching
– Clear and concise way to handle all branch conditions

35. Why F#?
• Async Workflows
– Non-blocking IO
– Convert synchronous code into asynchronous code with
minimal code changes
– Similar to C# 5’s async-await feature, but available in F#
since 2007!

36. Thank You!

37. JackpotJoy Slots
http://apps.facebook.com/jackpotjoyslots
Bingo Lane
http://apps.facebook.com/bingolane
Here Be Monsters
http://apps.facebook.com/herebemonsters
Building a MMORPG
http://bit.ly/1hjqoL8
http://slidesha.re/18MD4XY
Google I/O 2013 – Here Be BigQuery
http://bit.ly/1fHjbce