Mar 27, 2025
Let's Take a Look at... JEP 483: Ahead-of-Time Class Loading & Linking!
In the "Let’s Take a Look at…!" blog series I am exploring interesting projects, developments and technologies in the data and streaming space. This can be KIPs and FLIPs, open-source projects, services, relevant improvements to Java and the JVM, and more. The idea is to get some hands-on experience, learn about potential use cases and applications, and understand the trade-offs involved. If you think there’s a specific subject I should take a look at, let me know in the comments below.
Update March 28: This post is on being discussed Hacker News 🍊
Java 24 got released last week, and what a meaty release it is: more than twenty Java Enhancement Proposals (JEPs) have been shipped, including highlights such as compact object headers (JEP 450, I hope to spend some time diving into that one some time soon), a new class-file API (JEP 484), and more flexible constructor bodies (JEP 492, third preview). One other JEP which might fly a bit under the radar is JEP 483 ("Ahead-of-Time Class Loading & Linking"). It promises to reduce the start-up time of Java applications without requiring any modifications to the application itself, what’s not to be liked about that? Let’s take a closer look!
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Mar 18, 2025
The Synchrony Budget
Update March 27: This post is being discussed on Hacker News
For building a system of distributed services, one concept I think is very valuable to keep in mind is what I call the synchrony budget: as much as possible, a service should minimize the number of synchronous requests which it makes to other services.
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Mar 5, 2025
Let's Take a Look at... KIP-932: Queues for Kafka!
In the "Let’s Take a Look at…!" blog series I am going to explore interesting projects, developments and technologies in the data and streaming space. This can be KIPs and FLIPs, open-source projects, services, and more. The idea is to get some hands-on experience, learn about potential use cases and applications, and understand the trade-offs involved. If you think there’s a specific subject I should take a look at, let me know in the comments below!
That guy above? Yep, that’s me, whenever someone says "Kafka queue". Because, that’s not what Apache Kafka is. At its core, Kafka is a distributed durable event log. Producers write events to a topic, organized in partitions which are distributed amongst the brokers of a Kafka cluster. Consumers, organized in groups, divide the partitions they process amongst themselves, so that each partition of a topic is read by exactly one consumer in the group.
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Nov 27, 2024
Thoughts On Moving Debezium to the Commonhaus Foundation
If you are following the news around Debezium—an open-source platform for Change Data Capture (CDC) for a variety of databases—you may have seen the announcement that the project is in the process of moving to the Commonhaus Foundation. I think this is excellent news for the Debezium project, its community, and open-source CDC at large. In this post I’d like to share some more context on why I am so excited about this development.
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Nov 16, 2024
Building OpenJDK From Source On macOS
Every now and then, it can come in very handy to build OpenJDK from source yourself, for instance if you want to explore a feature which is under development on a branch for which no builds are published. For some reason I always thought that building OpenJDK is a very complex processing, requiring the installation of arcane tool chains etc. But as it turns out, this actually not true: the project does a great job of documenting what’s needed and only a few steps are necessary to build your very own JDK.
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Oct 18, 2024
CDC Is a Feature Not a Product
During and after my time as the lead of Debezium, a widely used open-source platform for Change Data Capture (CDC) for a variety of database, I got repeatedly asked whether I’d be interested in creating a company around CDC. VCs, including wellknown household names, did and do reach out to me, pitching this idea.
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Oct 6, 2024
How I Am Setting Up VMs On Hetzner Cloud
Whenever I’ve need a Linux box for some testing or experimentation, or projects like the One Billion Row Challenge a few months back, my go-to solution is Hetzner Online, a data center operator here in Europe.
Their prices for VMs are unbeatable, starting with 3,92 €/month for two shared vCPUs (either x64 or AArch64), four GB of RAM, and 20 TB of network traffic (these are prices for their German data centers, they vary between regions). four dedicated cores with 16 GB, e.g. for running a small web server, will cost you 28.55 €/month. Getting a box with similar specs on AWS would set you back a multiple of that, with the (outbound) network cost being the largest chunk. So it’s not a big surprise that more and more people realize the advantages of this offering, most notably Ruby on Rails creator David Heinemeier Hansson, who has been singing the praise for Hetzner’s dedicated servers, but also their VM instances, quite a bit on Twitter lately.
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Aug 26, 2024
Leader Election With S3 Conditional Writes
Update Aug 30: This article is discussed on Hacker News and lobste.rs.
In distributed systems, for instance when scaling out some workload to multiple compute nodes, it is a common requirement to select a leader for performing a given task: only one of the nodes should process the records from a Kafka topic partition, write to a file system, call a remote API, etc. Otherwise, multiple workers may end up doing the same task twice, overwriting each other’s data, and worse.
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Jul 6, 2024
Shell Spell: Extracting and Propagating Multiple Values With jq
In my day job at Decodable, I am currently working with Terraform to provision some cloud infrastructure for an upcoming hands-on lab. Part of this set-up is a Postgres database on Amazon RDS, which I am creating using the Terraform AWS modules. Now, once my database was up and running, I wanted to extract two dynamically generated values from Terraform: the random password created for the root user, and the database host URL. On my way down the rabbit hole for finding a CLI command for doing this efficiently, I learned a few interesting shell details which I’d like to share.
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Mar 18, 2024
A Zipping Gatherer
The other day, I was looking for means of zipping two Java streams: connecting them element by element—essentially a join based on stream offset position—and emitting an output stream with the results. Unfortunately, there is no zip() method offered by the Java Streams API itself. While it was considered for inclusion in early preview versions, the method was removed before the API went GA with Java 8 and you have to resort to 3rd party libraries such as Google Guava if you need this functionality.
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