@parttimen3rd profile picture
Johannes Bechberger @parttimen3rd

Hacking on OpenJDK and profilers at @SweetSapMachine

Joined July 2012
  • Tweets 1,293
  • Following 115
  • Followers 1,655
304 Photos and videos
1/ I made slidev-polls: self-hosted live audience polling for @Slidevjs decks. Drop a PollResults component on a slide; advance to it; audience joins from a phone, votes, results animate live on the slide in your deck's theme. No tab-switching. github.com/asm0dey/slidev-po…

GitHub - asm0dey/slidev-polls: Live audience polling for Slidev presentations. One container ships...

Live audience polling for Slidev presentations. One container ships the API, voter page, admin UI, and a Slidev addon that renders results on-slide. - asm0dey/slidev-polls

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Want to make vegan waffles that don't rip or stick even when doing large badges on commercial-grade equipment? Here is a recipe that gives you proper heart waffles with inexperienced labor: mostlynerdless.de/blog/2026/…

Vegan Waffle Recipe - Mostly nerdless

A vegan waffle recipe for waffles that don't riped apart or stick, using the power of food additives. Made for big events.

mostlynerdless.de
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Femtojar is a new tool and Maven plugin that reduces the size of your tool's JAR files using ProGuard, Zopfli, and a custom classloader. Read more on it in my latest blog post: mostlynerdless.de/blog/2026/…

Honey, I shrank the JARs - Mostly nerdless

Femtojar is a new tool and Maven plugin to reduce the JAR files of your tools using ProGuard, Zopfli and a custom classloader.

mostlynerdless.de
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Johannes Bechberger retweeted
P99CONF
@P99CONF
Apr 24
Thanks to new features of the #Linux kernel, anyone can write a basic Linux scheduler and use it to fuzz concurrency bugs or optimize for specific workloads. Jake Hillion and @parttimen3rd showed how to do it at #P99CONF. Watch it free here > ow.ly/E9He50XmveV #ScyllaDB
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Does anyone here work at #SAP and want to show off a cool #opensource project they work on (at least partially) on company time? Then please message me, as I'm looking for people to tell cool stories in an SAP internal OSPO meetup in Walldorf. Please share...
A picture of a home-made croissant, which you can enjoy as a speaker at the open-source meetup

ALT A picture of a home-made croissant, which you can enjoy as a speaker at the open-source meetup

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Benefits for the speaker: A fun morning, bretzels, home-made croissants, and help in preparing your presentation by an experienced speaker (me).
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I released a new version of ap-loader that wraps the newest async-profiler 4.4 version: github.com/jvm-profiling-too…

Release Loader for 4.4 (v13): async-profiler 4.4 · jvm-profiling-tools/ap-loader

ap-loader v13 Fix bug in AsyncProfilerLoader.getVersion() that caused it to return the same version number twice and crash The following is copied from the wrapped async-profiler release by Andre...

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JCmd allows you to quickly get information on an existing JVM, like thread-dumps. In this blog post, you'll learn to send commands programmatically: mostlynerdless.de/blog/2026/…

Calling jcmd Commands Programmatically - Mostly nerdless

JCmd allows you to quickly get information on an existing JVM, like thread-dumps. In this blog post you'll learn to send commands programmatically.

mostlynerdless.de
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A secret: Being able to submit a talk to JPrime on it is a good incentive to implement a feature :)
JPrime Conference@jPrimeConf
Apr 16
Johannes Bechberger @parttimen3rd is back to Sofia to tell us about JDK 25's new CPU-Time Profiler! Live at #jPrime26! Grab Your Pass: 🗓️ 3-4 June 2026 ! 📍 Sofia 🇧🇬 ! 🎫 jprime.io/tickets
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Ever looked at a HotSpot error file and thought “nope”? I wrote a guide built a VSCode highlighter and a browser redaction tool. mostlynerdless.de/blog/2026/…

On HotSpot Error Files and Useful Tools - Mostly nerdless

Learn all about HotSpot Error Files, a new syntax highlighter for VSCode and a redaction tool running directly in your browser.

mostlynerdless.de
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I just updated femtocli, my tiny (<50KB) CLI option parsing library. More bug fixes, better type conversions, and documentation: github.com/parttimenerd/femt…

Release Release 0.4.0 · parttimenerd/femtocli

Added Builtin type converters for short, byte, and char fields ${COMPLETION-CANDIDATES} and ${DEFAULT-VALUE} placeholder expansion in @Parameters descriptions Changed Increased minimal JAR size ...

github.com
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Johannes Bechberger retweeted
P99CONF
@P99CONF
Mar 20
Thanks to new features of the #Linux kernel, anyone can write a basic Linux scheduler and use it to fuzz concurrency bugs or optimize for specific workloads. Jake Hillion and @parttimen3rd showed how to do it at #P99CONF. Watch it free here > ow.ly/E9He50XmveV #ScyllaDB
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Java 26 is here, but it's boring. Nothing really exciting. But that's a good thing, as the boring stability is what made Java successful: mostlynerdless.de/blog/2026/…

Java 26 is boring, and that's a good thing - Mostly nerdless

Java 26 is here, but it's boring. Nothing really exciting. But that's a good thing, as the boring stability is what made Java successful.

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Parsing JSON is not hard; we can easily build a parser that directly follows a (transformed) JSON grammar, creating femtojson in the process: mostlynerdless.de/blog/2026/…

Writing a tiny JSON Parser - Mostly nerdless

Parsing JSON is not hard, we can easily build a parser that directly follows a (transformed) JSON grammar, creating femtojson in the process.

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Java Heap Dumps might contain sensitive information; with hprof-redact, you can easily remove it. Learn more in this blog post: mostlynerdless.de/blog/2026/…

Redacting Data from Heap Dumps via hprof-redact - Mostly nerdless

Java Heap Dumps might contain sensitive information, with hprof-redact you can easily remove it. Learn more in this blog post.

mostlynerdless.de
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Command-line parser libraries don't have to be big to support everything you need, like subcommands, validators, and Java-agent-style argument parsing: Introducing femtocli, with a 45KB JAR file. Read more at mostlynerdless.de/blog/2026/…

Femtocli: A small but mighty CLI library for small CLI tools in < 45KB - Mostly nerdless

Command-line parser libraries don't have to be big to support everything you need: Introducing femtocli, which is smaller than 45KB.

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Redact sensitive data from Java Flight Recorder and JVM crash logs with jfr-redact, a tool for safely sharing profiling and error files: mostlynerdless.de/blog/2026/…

Redacting Sensitive Data from Java Flight Recorder Files - Mostly nerdless

Redact sensitive data from Java Flight Recorder and JVM crash logs with jfr-redact, a tool for safely sharing profiling and error files.

mostlynerdless.de
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Think you really know Java? ☕ Guess the Java version from code snippets in my Java Version Quiz: mostlynerdless.de/java-game/

Guess the Java Version

Guess the Java version of a code snippet in this fun game (Java 1.0 to Java 25).

mostlynerdless.de
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In this week's blog post, I explain how a chaotic eBPF-based scheduler helps reproduce rare concurrency bugs, illustrated with a real-world OpenJDK case: mostlynerdless.de/blog/2026/…

Reproducing a Tricky Bug in Minutes With a Custom Linux Scheduler Written in Java - Mostly nerdless

How a chaotic eBPF-based scheduler helps reproduce rare concurrency bugs, demonstrated with a real OpenJDK case.

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A tiny puzzler: Is this valid Java? import java.util.function.Predicate; public class Test { Predicate<String> f = (var a) -> a.isEmpty(); }
58% yes
42% no
19 votes • Final results
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