Nov 29, 2021
O Kafka, Where Art Thou?
The other day, I came across an interesting thread in the Java sub-reddit, with someone asking: "Has anyone attempted to write logs directly to Kafka?". This triggered a number of thoughts and questions for myself, in particular how one should deal in an application when an attempt to send messages to Kafka fails, for instance due to some network connectivity issue? What do you do when you cannot reach the Kafka broker?
Read More...
Nov 22, 2021
Refining The Return Type Of Java Methods Without Breaking Backwards-Compatibility
If you work on any kind of software library, ensuring backwards-compatibility is a key concern: if there’s one thing which users really dislike, it is breaking changes in a new version of a library. The rules of what can (and cannot) be changed in a Java API without breaking existing consumers are well defined in the Java language specification (JLS), but things can get pretty interesting in certain corner cases.
The Eclipse team provides a comprehensive overview about API evolution guidelines in their wiki. When I shared the link to this great resource on Twitter the other day, I received an interesting reply from Lukas Eder:
I wish Java had a few tools to prevent some cases of binary compatibility breakages. E.g. when refining a method return type, I’d like to keep the old method around in byte code (but not in source code). I think kotlin has such tools? In the remainder of this post, I’d like to provide some more insight into that problem mentioned by Lukas, and how it can be addressed using an open-source tool called Bridger.
Read More...
Nov 12, 2021
JDK Flight Recorder Events in GraalVM Native Binaries
If you have followed this blog for a while, you’ll know that I am a big fan of JDK Flight Recorder (JFR), the low-overhead diagnostics and profiling framework built into the HotSpot Java virtual machine. And indeed, until recently, this meant only HotSpot: Folks compiling their Java applications into GraalVM native binaries could not benefit from all the JFR goodness so far.
Read More...
Nov 2, 2021
Debezium and Friends – Conference Talks 2021
If you love to attend conferences around the world without actually leaving the comfort of your house, 2021 certainly was (and is!) a perfect year for you. Tons of online conferences, many of them available for free, are hosting talks on all kinds of topics, and virtual conference platforms are getting better, too.
As the year is slowly reaching its end, I thought it might be nice to do a quick recap and gather in one place all the talks on Debezium and change data capture (CDC) which I did in 2021.
Read More...
Oct 24, 2021
What's on My Desk?
I’ve been working from home exclusively for the last nine years, but it was only last year that I started to look into ways for expanding my computer set-up and go beyond the usual combination of having a laptop with your regular external screen. The global COVID-19 pandemic, the prospect of having more calls with colleagues than ever (no physical meetings), and the constantly increasing need for recording talks for online conferences and meet-ups made me reevaluate things and steadily improve and fine tune my set-up, in particular in regards to better video and audio quality.
Read More...
Oct 18, 2021
Executable JavaDoc Code Snippets
It has been just a few weeks since the release of Java 17, but the first changes scheduled for Java 18 begin to show up in early access builds. One feature in particular that excites me as a maintainer of different Java libraries is JEP 413 ("Code Snippets in Java API Documentation").
Read More...
Aug 29, 2021
Resource Bundle Look-ups in Modular Java Applications
The ResourceBundle class is Java’s workhorse for managing and retrieving locale specific resources, such as error messages of internationalized applications. With the advent of the module system in Java 9, specifics around discovering and loading resource bundles have changed quite a bit, in particular when it comes to retrieving resource bundles across the boundaries of named modules.
In this blog post I’d like to discuss how resource bundles can be used in a multi-module application (i.e. a "modular monolith") for internationalizing error messages. The following requirements should be satisified:
Read More...
Aug 4, 2021
Introducing JfrUnit 1.0.0.Alpha1
Unit testing, for performance
It’s with great pleasure that I’m announcing the first official release of JfrUnit today!
JfrUnit is an extension to JUnit which allows you to assert JDK Flight Recorder events in your unit tests. This capability opens up a number of interesting use cases in the field of testing JVM-based applications:
You can use JfrUnit to ensure your application produces the custom JFR events you expect it to emit
You can use JfrUnit to identify potential performance regressions of your application by means of tracking JFR events e.g. for garbage collection, memory allocation and network I/O
You can use JfrUnit together with JMC Agent for whitebox tests of your application, ensuring specific methods are invoked with the expected parameters and return values
Read More...
May 28, 2021
Three Plus Some Lovely Kafka Trends
Over the course of the last few months, I’ve had the pleasure to serve on the Kafka Summit program committee and review several hundred session abstracts for the three Summits happening this year (Europe, APAC, Americas). That’s not only a big honour, but also a unique opportunity to learn what excites people currently in the Kafka eco-system (and yes, it’s a fair amount of work, too ;).
While voting on the proposals, and also generally aspiring to stay informed of what’s going on in the Kafka community at large, I noticed a few repeating themes and topics which I thought would be interesting to share (without touching on any specific talks of course). At first I meant to put this out via a Twitter thread, but then it became a bit too long for that, so I decided to write this quick blog post instead. Here it goes!
Read More...
May 17, 2021
Exploring ZooKeeper-less Kafka
Sometimes, less is more. One case where that’s certainly true is dependencies. And so it shouldn’t come at a surprise that the Apache Kafka community is eagerly awaiting the removal of the dependency to the ZooKeeper service, which currently is used for storing Kafka metadata (e.g. about topics and partitions) as well as for the purposes of leader election in the cluster.
The Kafka improvement proposal KIP-500 ("Replace ZooKeeper with a Self-Managed Metadata Quorum") promises to make life better for users in many regards:
Better getting started and operational experience by requiring to run only one system, Kafka, instead of two
Removing potential for discrepancies of metadata state between ZooKeeper and the Kafka controller
Simplifying configuration, for instance when it comes to security
Better scalability, e.g. in terms of number of partitions; faster execution of operations like topic creation
Read More...
