JUG Workshops Bern and Zurich 2023

In November 2023 (13-14th), I am going to give workshops in Bern and Zurich, Switzerland. They are the extended version of my DevoxxPL MICROBENCHMARKING - The Art of Realizing One is Wrong talk. But because these will be workshops, things will be hands-on. So bring your laptop and let’s master the maze of benchmarking.

Accento Java/Web/Dev 2023

If you want to see the Parallel Programming is Hard talk (in German this time, slides in English) in person, join me for Accento 2023 in Karlsruhe, Germany on 24th October 2023.

JUG Saxony Day 2023

I am looking forward to meet you at the JUG Saxony Day 2023 in Dresden on 29 September 2023. This year, my presentation talks about good and hopefully high quality code (not clean code, that is a different story). We will touch simple ideas to motivate you to think about your very own code. In addition, we will talk about APIs, style, tests, and of course, about the longevity of code. See you there!

Devoxx Poland 2023

I was an honor to be invited to speak at Devoxx Poland 2023. It was a really fun conference and I am grateful to have met so many wonderful people, speakers and regular attendees alike.

My first talk was about the right approach to microbenchmarking and the mistakes you can make if you try it a little too naively - MICROBENCHMARKING - The Art of Realizing One is Wrong. About 60 people attended and I was rated with 4.5 of 5 stars. I tried to put too much into the presentation so I had to rush towards the end. Sorry about that, but take as much time as you need to go through the slides.

René Schwietzke presenting at Devoxx Poland 2023
Figure 1. René Schwietzke presentating at Devoxx Poland 2023
René Schwietzke presenting at Devoxx Poland 2023
Figure 2. Microbenchmarking - The Art of Realizing One is Wrong on YouTube

Friday’s was all about parallel programming and why it is so important to know at least some details about the internals of the JVM in order to programm correctly. PARALLEL PROGRAMMING IS HARD - Why you really need synchronization and it is not what you think. 350 people showed interest and attended my session. It was rated 4.35 out of 5 stars. Many thanks to Douglas Q Hawkins and his 2017 Devoxx talk on Concurrency Concepts in Java. It was both an inspiration and a foundation for my talk.

René Schwietzke presenting at Devoxx Poland 2023
Figure 3. René Schwietzke, Devoxx Poland 2023, Parallel Programming is Hard
René Schwietzke presenting at Devoxx Poland 2023
Figure 4. Parallel Programming is Hard on YouTube

JUG Saxony Day 2022

This talk is about the Java Memory Model and what you should know to write correct multi-threaded code or at least know that you might not have to care about. It shows some of the details that modern languages and frameworks typically fully hide but Java partially still exposes due to its history. When you write a library for multi-threaded use, make sure you understand what you do. If you consume such a library, you hopefully can really on the quality and consistency provided. If the performance of your application is mediocre, maybe you find a possible reason here.

Cover of the Java Memory Model Presentation

Data Science Day 2022

When load and performance testing, a lot of data is captured. This presentation talks about the sheer amount (293,084 data points per second) and how this data is later condensed down to a few meaningful metrics. All of this, hopefully, without losing too much information and still transporting the most important facts.

Cover of the Presentation for the Data Science Day 2022

This talk has been recorded as well and it was given in English.

CinJUG 2022

A newer version of my High Performance Java talk was given at a CinJUG meetup in 2022.

CinJUG 2022

During the pandemic, I gave a remote presentation to the Cincinnati Java User Group about the Java Memory Model.

JavaLand 2020 (canceled)

This is my presentation that was scheduled for JavaLand 2020 but the entire conference got canceled due to the pandemic (in case you read that sometime in future, that was the Covid-19 pandemic). This talk is about all the tricks the JVM applies to get your code executed as quickly as possible. That includes compiler and optimization stages, dropping of code, and more. Also, it is about the modern CPUs and how they optimize code execution. Your code runs in parts concurrently on the CPU without you even knowing that.

Cover of the Slidedeck

DevTest Leeds 2019

When testing load and performance, one always faces the problem how to communicate the state and results. Not every stakeholder understands numbers as well as the load testers do, therefore communication might raise more questions than it answers. This talk suggests a simple rating system to convey a test result to many different people in a consitent manner.

Cover of the DevTest Leeds Presentation 2019

JUG Saxony Day 2019

The Javaland 2020 presentation, with marginal changes, was also given at the JUG Saxony Day 2019 in Dresden.

Please note, I was horribly overrunning and so I continued into the lunch break. This part has not been recorded.


This section shows my presentations given, often not any different from a talk. Typically, the crowd is smaller and it was given to a more uniform audience, such as a company department or a group of students.



All my presentations, some limitations apply, typically use Reveal.JS and my very own Less-based theme. Please note, the version that is used in these presentations is way older than the latest Reveal.JS version you find on GitHub. My theme might not fit anymore.

Feel free to use my theme or the Less approach for your own work and just feel inspired to use Reveal.JS. Especially, when you want a very uniform styling that can be easily adjusted (just a little bit of CSS and all presentations are updated) or you have to display source code a lot.