Akka/Scala vs Groovy for a Periodic Process

Last fall I created two different processes that were responsible for a reoccurring task of pulling data and broadcasting it elsewhere. The Akka based project pulled the newest meetups from the meetup page and then rebroadcasted them via Reddit and Twitter. The Groovy-based application pulled posts from a forum and then created a summary post of the posts pulled.

Both applications were reoccurring and were only activated on a schedule. However, there were two different outcomes. The Groovy based jar was scheduled as a cronjob and exits when done. The Akka process is set up as a systemd service and remains up.

Last fall I created two different processes that were responsible for a reoccurring task of pulling data and broadcasting it elsewhere. The Akka based project pulled the newest meetups from the meetup page and then rebroadcasted them via Reddit and Twitter. The Groovy-based application pulled posts from a forum and then created a summary post of the posts pulled.

Both applications were reoccurring and were only activated on a schedule. However, there were two different outcomes. The Groovy based jar was scheduled as a cronjob and exits when done. The Akka process is set up as a systemd service and remains up.

How did it turn out?

Both of the solutions work and have required very little maintenance. When running, the Groovy process takes up less than 70mb of memory, and the Akka based process takes more than 200mb  of memory. [It’s showing as 0.3% memory usage on a 65gb machine] (It’s written in Scala, and brings in Akka) Nether of the processes are intense enough to make a noticeable effect on the CPU. The ultimate package size is the following: Akka- 42mb Groovy- 12mb. (That is a little deceptive as that that the Groovy process contains less 3rd party libraries, but the amount of libraries that Scala and Akka bring in are a lot).

Now it comes down to probably the biggest concern: The time it took to develop. It took a month of lunches to develop the Scala and Akka based application. It took so long because I had to find and get up to speed on the Scala-based libraries for working with Rest services (I had spun my wheels with different clients), Scalalikejdbc, and Twitter4j. I learned another lession: Don’t use SBT. It’s a pain to use when compared to Gradle or Maven. On top of all of that I had a very challenging lesson: Don’t mix Scala versions for dependencies that weren’t compiled against the Scala version that your application is using.

The Groovy-based application took three lunches to write. One lunch (~30-40min) to write the main logic, the rest for the packaging. (The worst part of this was researching on how to make a fat Jar for Groovy under Gradle).

What did I learn?

Akka is an amazing piece of technology. I like using it, and I like using Scala. However it turns out for a process that is meant to be periodic, using REST calls: you are far better off writing the process in Groovy, letting Linux handle scheduled execution and getting it done quicker.

When would I use Akka? I would use it for a system that would expect constant requests, and that it had to be highly reactive, may include complexity, and would expect a high throughput. (The REST service is a good example for this)