Actor Model Concurrency Approach
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Actor Model is one of the concurrency models in computing. This presentation covers basic concepts, ecosystem and use cases in actor model.
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Actor Model Concurrency Approach
- 1. ACTOR MODEL A DIFFERENT CONCURRENCY APPROACH Emre Akış @akisemre
- 2. • CONCURRENCY MODELS • HISTORY • CONCEPTS • +‘s & -’s • ECOSYSTEM • RESOURCES
- 3. • CONCURRENCY MODELS • HISTORY • CONCEPTS • +‘s & -’s • ECOSYSTEM • RESOURCES
- 4. • Sequential • Concurrent • Parallel • Mixed * http://leakfromjavaheap.blogspot.com.tr/2016/05/concurrency-vs-parallelism.html
- 5. • CONCURRENCY MODELS • HISTORY • CONCEPTS • +‘s & -’s • ECOSYSTEM • RESOURCES
- 6. • 1973, Carl Hewitt • 1986, Gul Agha • 1995, Ericsson : First Commercial Use • 2009, Jonas Boner
- 7. • CONCURRENCY MODELS • HISTORY • CONCEPTS • +‘s & -’s • ECOSYSTEM • RESOURCES
- 8. • The actor model in computer science is a mathematical model of concurrent computation that treats "actors" as the universal primitives of concurrent computation. • In response to a message that it receives, an actor can: make local decisions, create more actors, send more messages, and determine how to respond to the next message received.
- 9. • Encapsulated state • Behaviour • Indepedent control • Mailbox http://brianrepko.github.io/presentation-big-data-bioinfo/images/actor-model.png
- 10. Address • Identifies an actor • May also represent a proxy/forwarder to an an Actor • Contains location and transport information • Location transparency
- 11. Address • One actor may represent many actors (pool) • One actor may have many address Load Balancer Actor Actor Actor Actor Machine 1 Machine 2 Actor Actor Actor X Y Z
- 12. • Each actor has its own process (not intended as an OS process) and they don’t share state between them. • Actors can change their own states. • Actors can create other actors and when they do that they receive back the new actor address. • Actor exchange messages in an asynchronous fashion.
- 13. Handling Errors • Supervision : The running state of an actor is monitored and managed by another actor (Supervisor) https://petabridge.com/blog/how-actors-recover-from-failure-hierarchy-and-supervision/
- 14. • Address does not change during restarts • Mailboxes are persisted outside the actor instances http://getakka.net/docs/concepts/actors
- 15. • CONCURRENCY MODELS • HISTORY • CONCEPTS • +‘s & -’s • ECOSYSTEM • RESOURCES
- 16. • No shared memory and therefore locking is not required. • Race conditions greatly reduced. • It greatly simplifies the control flow of a program, each actor has its own process (flow of control) • Easy to distribute, across cores, across program boundaries, across machines. • It simplifies error handling code. • It makes it easier to build fault-tolerant systems.
- 17. • Too many actors ( Tracing ) • Testing • Debugging • Don’t work well when • shared state needed • need to achieve global consensus • synchronous behaviour is needed
- 18. • CONCURRENCY MODELS • HISTORY • CONCEPTS • +‘s & -’s • ECOSYSTEM • RESOURCES
- 19. • T https://azure.microsoft.com/en-us/blog/use-actors-to-talk-to-millions/ • F https://www.facebook.com/notes/facebook-engineering/facebook-chat/14218138919/ • W https://www.wired.com/2015/09/whatsapp-serves-900-million-users-50-engineers/ • sas
- 22. • CONCURRENCY MODELS • HISTORY • CONCEPTS • +‘s & -’s • ECOSYSTEM • RESOURCES
- 23. • https://en.wikipedia.org/wiki/Actor_model • http://wiki.c2.com/?ActorsModel • Hewitt, Meijer and Szyperski: The Actor Model @ • • •