Why we moved from Kotlin & Spring Boot to Go

Our product completely supports Java and we love Java developers. However, internally for our own code, we believe the era of the JVM is coming to an end.

We found these 3 things initially attractive about Go:

  1. Instant compile times and program startup for faster development
  2. Virtual threads for dealing with high concurrency workloads
  3. Value types to better control memory usage

We found a ton more to like later, but this was enough to give it a go.


Right off the bat, Go's compile-time enforced formatting rules and casing of variables seemed like a weird choice. However, soon after I warmed up to them knowing that they enforced a certain amount of code uniformity across our codebase.

The biggest hurdle though was the lack of an equivalent of a Spring Framework for Go. While the Go ecosystem has multiple libraries for all kinds of functionality, there didn't seem to be a standard way of doing things like logging, dependency injection, environment configuration, etc. We had to solve this before we could adopt Go in a major way in our organization. Thus, alongside developing the first few microservices, we kept working on an in-house framework, Gallium. The Gallium Framework could use a blog post of its own. In short, it standardizes on some libraries in the  Go ecosystem for things like Logging, DI, etc, and makes it easy to structure microservices for our environment. We keep evolving Gallium with learnings from each Go microservice we develop.

We do miss JOOQ though. goqu comes close, but its not the same.

Also, the time package could use some improvements:

Though, its still a lot better than the java.time insanity:

In the land of magic

We took one of our simpler but high throughout Spring Boot service called metric-query and converted it to Go. metric-query takes in queries from our dashboard and runs them against our metric database. Since our dashboards refresh every 2 seconds, it can get a lot of requests at once. In the JVM world, each of these requests would spawn a whole thread.

After converting to Golang, we saw the memory usage drop by 40x! We had to double-check that our charts were not faulty.

This convinced us we were  on the right path and the investment in Go was worth it.

We then converted our highest throughout service, metric-collector. It ingests data from all our agents and puts it on Kafka. It receives a ton of requests all at the same time. The Spring Boot version was maxing the CPU on the nodes it was deployed and eating up tons of memory.  Latency was all over the place.

Converting it to Go and watching the graphs was pure magic. CPU usage and latency dropped to almost nothing. Memory usage dropped to insignificant levels. This could be a case study for virtual threads.

We have continued converting each microservice from Kotlin/Spring Boot to Go and its magical each time watching those graphs drop.

Looking back at JVM world

I have been programming on the JVM for almost 2 decades. Switching to Go was quite a change for me personally too.

But looking back, the Java/Spring world seems to be toppling to maintain compatibility with all its legacy. It is mind-boggling to think a microservice in 2021 still needs Tomcat to run. Spring MVC is layers and layers of code to get Java Servlets, which were released in 1996, somehow feel relevant in 2021. Kotlin is another massive layer to make Java feel like a modern language.

The Maven/Gradle build system seems like a ridiculous, unnecessary complexity compared to Go's dependency management.

The JVM, Java, and Spring were great for an era indeed. In 2021, they feel like an 80-yr old trying to compete in the Olympics by taking artificial performance enhancing drugs. Switching to Go feels like a refreshing, exciting change.