[concurrency-interest] Coordinated Runnables

Roland Kuhn rk at rkuhn.info
Thu Aug 29 12:40:34 EDT 2013

Hi Alexei,

Akka implements the Actor Model as described by Carl Hewitt in 1973 quite closely (the deviations are not relevant for this discussion); what you describe is closer to CSP or the (synchronous) π calculus. Asynchronous message passing results in a better decoupling of sender and receiver of a communication, which is the important distinction here.

Petri nets can be used to model anything you want, including Actors or CSP, but directly implementing them will probably not achieve good scalability due to their synchronous (and therefore synchronized) transition semantics.


Dr. Roland Kuhn
Akka Tech Lead
Typesafe – Reactive apps on the JVM
twitter: @rolandkuhn

29 aug 2013 kl. 18:24 skrev Alexei Kaigorodov:

> Place is a term in Petri Net model - place where tokens wait to be processed. "Of type queue" means that tokens are stored in a queue. Another possible type, for "colorless" tokens, is just a counter for events, like semaphore. Single means actors in Scala and Akka can have only one input place (queue) for messages, while Petri Net Nodes (transitions) can have several, and this is very  natural for asynchronous programming, as illustrated at the picture in the referenced googledoc paper.
> On Thu, Aug 29, 2013 at 11:04 PM, √iktor Ҡlang <viktor.klang at gmail.com> wrote:
> Single place of type queue <-- wdym?
> On Thu, Aug 29, 2013 at 7:42 AM, Alexei Kaigorodov <alexei.kaigorodov at gmail.com> wrote:
> Yes it is an actor, in its initial meaning. But unfortunately, the term "actor" today mainly means restricted actor of Scala or Akka style (with single place of type queue), and I am in doubt if "actor" would not cause misunderstanding.
> On Thu, Aug 29, 2013 at 9:26 PM, Zhong Yu <zhong.j.yu at gmail.com> wrote:
> Hi Alexei, if in your model one place can be connected to only one
> transition, can't we model one transition with its input places as one
> actor?
> Zhong Yu  ://cs.oswego.edu/mailman/listinfo/concurrency-interest
> -- 
> Viktor Klang
> Director of Engineering
> Typesafe
> Twitter: @viktorklang
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