[erlang-questions] The quest for the perfect programming language for massive concurrency.

Aaron France aaron.l.france@REDACTED
Thu Jan 30 17:26:37 CET 2014

Then what about Clojure?

You can stay on the jvm, use Java  code and it has a focus on concurrency.

Whilst it fails hard on fault tolerance it could be an escape hatch for
those stuck with the jvm

On 30 Jan 2014 17:22, "kraythe ." <kraythe@REDACTED> wrote:

> Ok right up front, I'm a Java Guru, not a Scala or Erlang one. What that
> means is that I know more than most debs about the core java language, but
> enough to know where the problems are. And certainly java has many issues
> but it also has massive momentum. I think one of the issues with Java can
> be expressed in one little programming puzzle I came across recently:
> *In a relevant language, create an array of 1000 numbers. Initialize all
> of the values in the array to zero. Create two threads that run
> concurrently and which increment each element of the array one time.*
> Interesting? The solution in Scala that I came up with is the following.
> def mtmap[A](data : List[A], threads: Int, f: (A) => A) = {
>   import scala.concurrent.{ExecutionContext, Future, Await}
>   implicit val executor =
> java.util.concurrent.Executors.newFixedThreadPool(threads)
>   implicit val context =  ExecutionContext.fromExecutorService(executor)
>   val futures : Future[List[A]]= Future.traverse(data)(x => Future{f(x)})
>   import scala.concurrent.duration._
>   import scala.language.postfixOps
>   val results : List[A] = Await.result(futures, 1 minute)
>   results
> }
> Just thinking of doing this in Java will bring up some of the big problems
> with Java; I will leave it as a mental exercise for the reader. The problem
> is that Scala inherits some of them from the JVM and that has made me look
> into Erlang. The goal being to select a language for the development of a
> concurrent TCP/IP based application with thousands of users interacting in
> a small space.
> So far I think the contenders I have are Scala with Akka or Erlang. And
> yes, I know there are evangelists to both and I will post this to an Scala
> list to get their feedback as well (or something similar). Now, right up
> front I am not peeing on either language. They both rock or they wouldn't
> be on the list. The question is which should win the prize. There is no
> going back once development is 1000 hours down the road.
> *Scala: *
> *Pros:*
>    1. Based on Java Ecosystem so easier to staff because good Java devs
>    can convert to Scala.
>    2. Decent tools (which are getting better). Many libraries.
>    3. Static typing with type inference.
> *Cons:*
>    1. Based on Java Ecosystem and inherit the problems of that ecosystem
>    (i.e. immutable is a function of the design of a class, not of the language
>    so it can't be guaranteed.), Also library code under the hood is not as
>    rigorous as scala code in enforcing immutability so at some point you are
>    rolling dice here.
>    2. Scala is also more heavyweight than Erlang when it comes to
>    spawning thousands of processes. Erlang was built from the ground up to do
>    concurrency. For Scala its an Akka bolt on can carries the Java threading
>    nightmare (shared memory, etc).
>    3. Scala is not as fast. My server will be doing billions of vector
>    math calculations per day and they have to be in the terms of milliseconds
>    of latency. It has to be that if I have a user R in the server at position
>    V where V is a vector, I need to calculate all other actors within 50 units
>    and get that answer in milliseconds so that only the network latency is the
>    bottleneck. Some of this can be helped with algorithms like spatial grids
>    and so on but still we are looking at a couple of hundred vector math calls
>    per second.
>    4. Scala is harder to hook up to dozens of nodes and move actors from
>    node x to node y than Erlang, mainly because that was one of the design
>    goals of Erlang.
> *Erlang:*
> *Pros:*
>    1. Built for concurrency. Can handle dozens of hardware nodes, build
>    massive applications of the kind I am trying to deploy. Think of 100k users
>    connecting to the cluster with a TCP connection and interacting over that
>    connection which interacts with any or all of the other 100k actors.
>    2. Built from the ground up with immutability in mind. Immutability is
>    a language feature, not compromisable. Its not JVM based and so is not
>    under the same issues as Java is.
>    3. There is merit in the thought that static typing is sometimes a
>    hinderance to a language.
> *Cons:*
>    1. The tools are, well frankly, garbage. Sorry, in 2014 to be pushed
>    back to coding with VIM and makefiles is primitive. Rebar is crytptic and
>    just the pet project of a guy on GIT. Compared to Gradle, Maven and even
>    (though I don't care for it much) SBT, rebar is ... lacking. I want to
>    spend time working on my business logic, not fighting tools. There are
>    plugins for eclipse and intellij but they have minimal functionality and i
>    keep reverting back to vim.
>    2. Much harder to staff than Scala because it is not Java based.
>    3. Fewer general purpose libraries and no major central repositories.
>    I don't want to write code to create JSON, that isnt part of my business
>    scope. I will pick that one of the shelf If i can.
>    4. Records as the only structured data type is ... annoying.
> The problem I have is I can't find the perfect solution. Erlang is
> compelling but also is Scala.
> Opinions?
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