Scala Actors: Unifying thread-based and event-based programming

http://blog.acolyer.org/2014/12/12/scala-actors-unifying-thread-based-and-event-based-programming/

by tambourine_man • 12 years ago

30 18 12 years ago

blog.acolyer.org

pacala2• 12 years ago

TL;DR This is all the concrete code from the article:

    1 awaitPing andThen sendPong

I'd find more valuable blog posts explaining how to solve a concrete problem with concrete code using the Actor model than mishmashes of quotes appealing to various authorities.

lomnakkus8• 12 years ago

I was going to chide you for unfairly calling out the lack of code vs. the abundance abstract concepts, but... yeah. This was pretty much content-free except for a few links to... things.

pacala2• 12 years ago

I'm working hard to keep a professional, factual approach. There is more under the surface:

A. (Appeal to authority) Until very recently, I've worked for years at a huge and very successful distributed systems company. There wasn't a single system using the actor model I ran into. I haven't heard anyone advocating for the actor model. Everything was a service with an RPC interface. At least one other huge competitor is well known for a service-oriented revolution phase.

B. (Unsubstantiated anecdote). The majority of advocacy around Actors I've come across lacks substance. There is very little exemplification of what problems are solved or comparison to other ways to solve the problem. But it's almost guaranteed to have an appeal to Erlang's authority thrown somewhere in there. The OP is a canonical example.

C. (Concrete example, you can start calling me out on it). Speaking of actors, messaging and distributed systems, I just don't get what's the point of sending an unreliable message if you don't check the response and tailor your reactions based on it. Which is basically doing RPCs. How do you even test something like "endpoint.send(request)" when messages can get lost?!

Sorry if I sound harsh and unfair. I only bring this up because I'm forced by exterior circumstances to pay attention to "Actor model" tradeoffs.

strmpnk• 12 years ago

I find this paper on an approach for Haskell much more interesting: http://www.cis.upenn.edu/~stevez/papers/LZ06b.pdf

lomnakkus8• 12 years ago

Indeed. Whenever I see a new blog post espousing the virtues of Actors, I tend to cringe.

The short version is: Programming as if all your state is potentially distributed is counterproductive. I want a system which can statically distinguish distributed from local state (via types). For example, something like what Cloud Haskell is (hopefully!) going to be.

saryant• 12 years ago

Actors aren't just about distributed state, they're about any state that could be accessed or modified concurrently. Distributed systems don't have to come into play for actors to be useful. Actors provide a sane way to deal with mutable state with potentially multiple readers or writers.

lostcolony3• 12 years ago

How are you distinguishing 'distributed state' from 'local state'?

acolyer• 12 years ago

That was the immediately preceeding paper in the review series... http://blog.acolyer.org/2014/12/11/a-language-based-approach... !

Scala Actors: Unifying thread-based and event-based programming

Related Stories