Working With ZeroMQ Module In AKKA 2.0

Akka framework supports ZeroMQ in its ZeroMQ extensions module. Akka is a great framework and we have our product built on its version 1.3x. We were looking at ZeroMQ support in our product and we stumbled on this issue. We found that ZeroMQ applications built on Akka extensions are running slower than an application built in plain scala.

Please read about our discussion thread on Akka user list. The issue is now accepted issue no #1963 you can view it here in assembla. The bug is now resolved great work by typesafe guys especially Roland Kuhn. This blog will deal with workaround till it is pushed in the new release. The workaround has a caveat that the Subscriber hangs on to the thread that created it. It is like the pinned dispatcher with allocated thread to the subscriber. Please look at the comment below.

I will create two simple PUB/SUB application one by using Akka based extension and one without it and then measure their throughput in order to compare their performance.

Let’s start the project by creating a sbt based project. Here is my build.sbt. It contains Akka 2.0 dependencies and that of ZeroMQ scala binding.

name := "Akka2Bench"

version := "1.0"

scalaVersion := "2.9.1"

resolvers += "Typesafe Repository" at "http://repo.typesafe.com/typesafe/releases/"

libraryDependencies ++= Seq(
	"com.typesafe.akka" % "akka-actor" % "2.0",
	"com.typesafe.akka" % "akka-remote" % "2.0",
	"com.typesafe.akka" % "akka-zeromq" % "2.0",
	"com.typesafe.akka" % "akka-testkit" % "2.0",
	"com.typesafe.akka" % "akka-kernel" % "2.0"
)

libraryDependencies += "org.zeromq" %% "zeromq-scala-binding" % "0.0.5"

I use eclipse IDE so here is the entry for sbteclipse plugin in my project/plugin.sbt

addSbtPlugin("com.typesafe.sbteclipse" % "sbteclipse-plugin" % "2.0.0")

Let’s start with the Publisher. It will create a publisher socket and then bind to it. But we want it to be wrapped in Akka based Actor. I will use its lifecycle method preStart to create publisher socket and bind to it. Here is the code.