Blog Posts

Akka uses the The Φ Accrual Failure Detector for failure detection, which is to say for answering the question of whether a node is alive or not. That’s one of the harder problems of distributed systems since it is virtually impossible (from the point of view of one node) to tell the difference of a remote system being completely unavailable ... Read More

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One anti-pattern I’ve observed in networked Akka applications is a tendency to forget that it is, well, networked and to treat the network as a friendly place. How does that look like? Well, consider the following piece of code: [crayon-597a16abe8702729450439/] Akka’s default message sending mechanism is the fire-and-forget tell method. And that works great – until it doesn’t. See, tell ... Read More

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Whilst I have always successfully discouraged my clients from using Akka Remoting in their application, I often get questions regarding remoting while talking about anti-patterns at conferences and user groups. Don’t get me wrong. I love Akka remoting. Especially the new Aeron-based Artery remoting version that is based on UDP rather than TCP. Whilst it maintains the same delivery guarantees, ... Read More

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Lagom is a framework for building reactive microservices in Scala or Java with an emphasis on developer productivity. I’ve had a chance to work with it for some time and would like to share my impressions about it. This is going to take a bit longer than just one post, so you’re reading part one of a 3-part series: Part ... Read More

The post Tour de Lagom Part 1: Lagom and microservices appeared first on manuel bernhardt.

Akka Streams is a powerful implementation on top of the Reactive Streams SPI for non-blocking asynchronous communication with back-pressure on the JVM. This post is not about explaining what this means, nor what Akka Streams does. The purpose of this post is to explain what on earth the NotUsed type in type signatures of Akka Streams is all about which ... Read More

The post Akka Streams – What is NotUsed all about appeared first on manuel bernhardt.

Tags: #akka #it

Akka anti-patterns: blocking
15.05.2017 07:59 by Manuel

This is probably one of the most frequent (and dangerous) anti-patterns when it comes to working with Akka. Let’s look at an adequate description of the mindset you must be in in order to use it: So maybe you didn’t actually want to see the world burn. Maybe you thought that this one time it was okay to call blocking ... Read More

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Choosing Akka as a tool is often – if not always – driven by the need for good performance. Surely, the actor model itself is appealing as a means for organizing and reasoning about code, but this isn’t in itself a good reason enough to use the Akka toolkit. If all you are concerned about is a nice way to ... Read More

The post Akka anti-patterns: being out of touch with the hardware appeared first on manuel bernhardt.

When you need to build your Scala project, but have no way to install SBT on your host, you can still do it if you have Docker.

There are few ready to use container images on DockerHub. We create our own.

All we need for that is to prepare a Dockerfile:

 FROM java:latest  
MAINTAINER Nikolay Kushin
ENV SBT_OPTS -Xmx2G -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -Xss2M -Duser.timezone=GMT
# install sbt
RUN dpkg -i sbt-$SBT_VERSION.deb
# install scala
RUN dpkg -i scala-$SCALA_VERSION.deb
# fetch base dependencies
RUN sbt compile
CMD ["sbt"]

Our Dockerfile is relatively easy and self-explaining.

Next step is to build an image. Save Dockerfile in some folder and execute following commande in terminal:

 docker build -t sbt-docker .  

Now when the image is ready we can create container with mounted source folder, containing our Scala project and run SBT.

 docker run -it --rm -v $(pwd):/src sbt-docker sbt docker:stage  

Thats it! Enjoy!
Simply run following script to install latest Scala and SBT on your Ubuntu:
The past weekend I was lucky enough to participate in an event held by Koding ( titled "Global Hackathon" (
Hackathon - is a kind of time-limited events, where participants work on projects for which in ordinary daily life there is no time as a rule. The main idea is to bring the idea to the finished prototype of the final product in the shortest possible time. Hackathon is named this way because participants can use all possible tools and ways to achieve this goal.

file-2.pngThe event was attended by 2000 teams from all around the world, selected from more than 19,000 applications. Maximum number of participants in the team was equal to 5. Many people like me was not fortunate enough to find teammates and had to work alone. 51 of the judges will find winners among completed projects and the most worthy of them will be awarded.

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