Gunnar Morling

Gunnar Morling

Random Musings on All Things Software Engineering

Gunnar Morling

Gunnar Morling

Random Musings on All Things Software Engineering

Recent posts

Jan 15, 2023

Getting Started With Java Development in 2023 — An Opinionated Guide

27 years of age, and alive and kicking — The Java platform regularly comes out amongst the top contenders in rankings like the TIOBE index. In my opinion, rightly so. The language is very actively maintained and constantly improved; its underlying runtime, the Java Virtual Machine (JVM), is one of, if not the most, advanced runtime environments for managed programming languages. There is a massive eco-system of Java libraries which make it a great tool for a large number of use cases, ranging from command-line and desktop applications, over web apps and backend web services, to datastores and stream processing platforms. With upcoming features like support for vectorized computations (SIMD), light-weight virtual threads, improved integration with native code, value objects and user-defined primitives, and others, Java is becoming an excellent tool for solving a larger number of software development tasks than ever before.

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Jan 5, 2023

Oh... This is Prod?!

I strongly believe that you should avoid connecting to production environments from local developer machines as much as possible. But sometimes, e.g. in order to analyse some specific kinds of failures, doing so can be inevitable. Now, if this is the case, I really, really want to be sure that I’m aware of the environment I am working in. I absolutely want to avoid a situation as in the catchy title of this post, when for instance you realize that you just ran some integration test against a production environment. In the context of working with the AWS CLI tool this means I’d like to be aware of the currently active profile by means of coloring my shell accordingly. Here’s how I’ve set this up using iTerm2 and zsh.

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Jan 3, 2023

Is your Blocking Queue... Blocking?

Java’s BlockingQueue hierarchy is widely used for coordinating work between different producer and consumer threads. When set up with a maximum capacity (i.e. a bounded queue), no more elements can be added by producers to the queue once it is full, until a consumer has taken at least one element. For scenarios where new work may arrive more quickly than it can be consumed, this applies means of back-pressure, ensuring the application doesn’t run out of memory eventually, while enqueuing more and more work items.

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Dec 18, 2022

Maven, What Are You Waiting For?!

As part of my new job at Decodable, I am also planning to contribute to the Apache Flink project (as Decodable’s fully-managed stream processing platform is based on Flink). Right now, I am in the process of familiarizing myself with the Flink code base, and as such I am of course building the project from source, too.

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Nov 30, 2022

The Insatiable Postgres Replication Slot

While working on a demo for processing change events from Postgres with Apache Flink, I noticed an interesting phenomenon: A Postgres database which I had set up for that demo on Amazon RDS, ran out of disk space. The machine had a disk size of 200 GiB which was fully used up in the course of less than two weeks. Now a common cause for this kind of issue are replication slots which are not advanced: in that case, Postgres will hold on to all WAL segments after the latest log sequence number (LSN) which was confirmed for that slot. Indeed I had set up a replication slot (via the Decodable CDC source connector for Postgres, which is based on Debezium). I then had stopped that connector, causing the slot to become inactive. The problem was though that I was really sure that there was no traffic in that database whatsoever! What could cause a WAL growth of ~18 GB/day then?

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Nov 28, 2022

Running a Quarkus Native Application on Render

This is a quick run down of the steps required for running JVM applications, built using Quarkus and GraalVM, on Render. Render is a cloud platform for running websites and applications. Like most other comparable services such as fly.io, it offers a decent free tier, which lets you try out the service without any financial commitment. Unlike most other services, with Render, you don’t need to provide a credit card in order to use the free tier. Which means there’s no risk of surprise bills, as often is the case with pay-per-use models, where a malicious actor could DDOS your service and drive up cost for consumed CPU resources or egress bandwidth indefinitely.

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Nov 3, 2022

Why I Joined Decodable

It’s my first week as a software engineer at Decodable, a start-up building a serverless real-time data platform! When I shared this news on social media yesterday, folks were not only super supportive and excited for me (thank you so much for all the nice words and wishes!), but some also asked about the reasons behind my decision for switching jobs and going to a start-up, after having worked for Red Hat for the last few years.

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Sep 6, 2022

An Ideation for Kubernetes-native Kafka Connect

Kafka Connect, part of the Apache Kafka project, is a development framework and runtime for connectors which either ingest data into Kafka clusters (source connectors) or propagate data from Kafka into external systems (sink connectors). A diverse ecosystem of ready-made connectors has come to life on top of Kafka Connect, which lets you connect all kinds of data stores, APIs, and other systems to Kafka in a no-code approach. With the continued move towards running software in the cloud and on Kubernetes in particular, it’s just natural that many folks also try to run Kafka Connect on Kubernetes.

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Aug 25, 2022

Testing Kafka Connectors

Kafka Connect is a key factor for the wide-spread adoption of Apache Kafka: a framework and runtime environment for connectors, it makes the task of getting data either into Kafka or out of Kafka solely a matter of configuration, rather than a bespoke programming job. There’s dozens, if not hundreds, of readymade source and sink connectors, allowing you to create no-code data pipelines between all kinds of databases, APIs, and other systems. There may be situations though where there is no existing connector matching your requirements, in which case you can implement your own custom connector using the Kafka Connect framework. Naturally, this raises the question of how to test such a Kafka connector, making sure it propagates the data between the connected external system and Kafka correctly and completely. In this blog post I’d like to focus on testing approaches for Kafka Connect source connectors, i.e. connectors like Debezium, which ingest data from an external system into Kafka. Very similar strategies can be employed for testing sink connectors, though.

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Jun 23, 2022

Ten Tips to Make Conference Talks Suck Less

Every so often, I come across some conference talk which is highly interesting in terms of its actual contents, but which unfortunately is presented in a less than ideal way. I’m thinking of basic mistakes here, such as the presenter primarily looking at their slides rather than at the audience. I’m always feeling a bit sorry when this happens, as I firmly believe that everyone can do good and even great talks, just by being aware of — and thus avoiding — a few common mistakes, and sticking to some simple principles.

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