1. CONCURRENCY
IN
PLAY 2.0
Ola Wiberg
Wednesday, 11 July, 12
2. OVERVIEW
• Background
• Play architecture
• Integrated Akka
• API
• Asynchronous IO
Wednesday, 11 July, 12
3. A PLATFORM FOR
THE FUTURE
"The web has evolved from
static to dynamic to real-time."
"Play is a framework for highly-scalable
real-time applications!"
Wednesday, 11 July, 12
4. DESIGN DECISIONS
• Designed for asynchronous HTTP
• Assumes that any request is long-lived (streams/sockets)
• Concurrency using Actors (Akka) instead of Threads
• Reactive (event based) model for IO
• Keep things simple!
Wednesday, 11 July, 12
5. BACKGROUND
Threads or Events
• One process/thread per request • Single process for all requests
• Resource intense / upper bound • Less resource intense
limit
• State maintained in program
• State is handled by the stack
• Single event-loop, with event
• Requests handled in "isolation" call-backs
• Easy to track control flow • Difficult to track control flow
• Apache, Tomcat • Lighttp, Nodejs
Wednesday, 11 July, 12
6. A BETTER SOLUTION
• Threads are good
• Events are good
• Why not make use of them both?
• To do it well the complete framework stack
needs to support it!
Wednesday, 11 July, 12
11. AKKA
• Akka is used internally for concurrency features in Play
• Built in ActorSystem to be used by the application
• play.api.libs.concurrent.Akka helper object
• Startup new ActorSystems
• Access remote ActorSystems
Wednesday, 11 July, 12
12. WHEN TO USE AKKA
• When executing long running tasks.
• Calculations, data crunching, long running queries.
• When accessing web services.
• When accessing remote ActorSystems.
• When scheduling tasks.
Wednesday, 11 July, 12
23. REACTIVE MODEL
Async IO
• Handling data streams reactively
• Remove IO stream limitation (Blocking, memory, threads)
• “React” to input only at a rate it is needed (no buffering)
• Implemented using Iteratees, Enumerators, Enumeratees
(Consumer/Producer Pattern)
• Topic for another presentation!
Wednesday, 11 July, 12
25. SUMMARY
• Play 2.0 is implemented for high concurrency applications
• Play 2.0 has a simple API for concurrency features
• Play 2.0 is great for:
• high throughput, low memory usage
• many concurrent requests / socket connection
Wednesday, 11 July, 12
