I'm happy that so many people find this helpful tool. I've just released a new version that improves performance and allows you to specify JVMs by part of their name, such as `jstall status plexus` to get the status of all running Maven instances.

I hope I'm not the only one who sometimes wonders: "What is my Java application doing right now?" When you don't see any output. This is where my tiny tool called JStall comes in, as you can read in my blog post at mostlynerdless.de/blog/2025/12...

In this week's blog post, you'll learn that JFR doesn't like arrays in other complex types as fields in custom JFR events, and what types are supported: mostlynerdless.de/blog/2025/12...

Discover how to create a Gridfinity chocolate advent calendar and chocolate QR codes in this week's brief blog post: mostlynerdless.de/blog/2025/12...

I'm happy to announce that my meta-agent (a Java agent that instruments other Java agents) now has a nicer Web UI (thanks @hardcoding.fr): github.com/parttimenerd...

In this week's blog post, I'll showcase how the meta-agent hot-patches the JVM to record the byte-code transformations of native Java agents: mostlynerdless.de/blog/2025/11...

Having a last name that comes early when sorted alphabetically sometimes has its advantages:

The JFR events collection website has a new home: sap.github.io/jfrevents Old links will still work and are forwarded to this location.

Running local AI models on Android is easy. In this week's blog post, I showcase my AI server app, which exposes LLMs to Termux and other apps: mostlynerdless.de/blog/2025/11...

I just released the newest version of ap-loader, a platform-independent async-profiler wrapper, which is now built on top of async-profiler 4.2: github.com/jvm-profilin...

Learn how to import JFR data into DuckDB, to easily query and analyze your profiling data in this week's blog post: mostlynerdless.de/blog/2025/10...

Learn how to compare objects from JFR recordings in Java and why this is slightly trickier than you might have expected in this week's blog post: mostlynerdless.de/blog/2025/10...

Learn how to silence the JFR startup messages and why you see them even with the default warning logging level in this week's blog post: mostlynerdless.de/blog/2025/09...

💪 Monday motivation: We are officially one month away from #P99CONF. eBPF has always been a popular topic, and this year is no exception. Don't miss @tanelpoder.com, @ddelnano.bsky.social, Jake Hillion, and @mostlynerdless.de on October 22-23: www.p99conf.io?latest_sfdc_... #ScyllaDB

Learn seven different ways to waste a specific amount of CPU-time in this week's blog post. Number seven will surprise you: mostlynerdless.de/blog/2025/09...

With Java 25, there is finally a CPU-time profiler in the OpenJDK. You can read more about this new profiler and some implementation details in my blog series starting with mostlynerdless.de/blog/2025/06... #java25

Learn how to profile Java applications in Cloud Foundry using the CF CLI Java plugin with SapMachine in my latest blog post: mostlynerdless.de/blog/2025/09...

Learn about the redundant synchronisation in the request queue of Java 25's new CPU time sampler and what we do about it in this week's blog post: mostlynerdless.de/blog/2025/09... P.S.: It also answers the really important question of whether the sampler queue is even a queue.

I just released a new version of my IntelliJ profiler plugin with support for the newest IntelliJ version and the newest async-profiler: plugins.jetbrains.com/plugin/20937...

Queue sizing is hard. Learn all about the sizing of the sampling queues in JDK 25's new CPU-time profiler in my latest blog post at mostlynerdless.de/blog/2025/08...

Sneak peek into my upcoming blog post:

To get you ready for @mostlynerdless.de and @jakehillion.me’s #P99CONF technical session on the Linux scheduler, we're sharing a deep dive from Johannes' hello-ebpf series that looks at concurrency testing using Custom Linux schedulers. www.p99conf.io/2025/08/06/h... #ScyllaDB

Seems like I won't be part of the great Devoxx Belgium conference this year.

TIL: the k3s uninstall script changes the hostname

In this week's blog post, learn how Java 25's new CPU-time profiler works internally, including signal handling, queue design, and async sampling: A deep dive into the core components behind the scenes. Read more at: mostlynerdless.de/blog/2025/07... #Java #OpenJDK #JFR #Profiling

I'm currently working on my blog post on the inner workings of the new JFR CPU-time profiler. But if you want to learn what other ideas I had, you can read my brain-dump ideas list from March 2025 at mostlynerdless.de/blog/2025/07...

I just saw that I published my last blog post more than a month ago. Guess what I'll be working on this week? I procrastinated and had other things to do, so I hope I get into my blogging rhythm again. There are many interesting topics (short and longer) lined up.

I just released ap-loader 4.1 (v10). ap-loader is a wrapper around async-profiler, conveniently packaging all platform versions in one JAR. You can find the newest release on GitHub (github.com/jvm-profilin...) and soon on Maven Central.

Btw. Firefox isn't supporting Java applets for 10 years (blog.mozilla.org/futurereleas...) and Chrome for 11 (blog.chromium.org/2013/09/sayi...), so essentially nobody will notice the removal of applets from Java.

RIP Java Applets. You made Java popular and helped it grow to what it is today. JEP 504: Remove the Applet API has been proposed to target (openjdk.org/jeps/504), so there will be no more applets with the next JDK (JDK 26).

Forget `dd`, `yes >> $HOME/fill_disk.txt` is the best way to reliably fill your disk till the brim. No need to check how much space is left. I used this successfully to test that a tool I'm working on works as expected without disk space left.

TIL: `jcmd $PID GC.heap_dump $FILE` wants the $FILE to either be an absolute location or relative to the current working directory of the Java application (not your current command)

If you want to see what I'm doing in my spare, watch this talk: app.media.ccc.de/v/gpn23-15-c...

Sadly no @javazone.bsky.social for me this year, after presentations in two years in a row. See you all hopefully somewhere else...

Learn how to use JFR queries and my new experimental query tool to explore your JFR recordings in this weeks blog post: mostlynerdless.de/blog/2025/06...

Learn all about Java 25's new CPU-time profiler and why it matters in this week's blog post: mostlynerdless.de/blog/2025/06...

I just updated the JFR events collection (sapmachine.io/jfrevents). It now includes JDK 25 and JDK 26 with my CPUTimeSample event:

Learn how to install and run Garden Linux on your smartphone using Termux and proot-distro in this week's short blog post: mostlynerdless.de/blog/2025/06...

Well...

"eBPF-based replacement for authbind, allowing administrators to control Unix users' permission to bind to specific system ports"

I needed a QR code for a presentation and found nythrox.github.io/halftone-qrc.... It allows you to add a picture to your QR code in a few different ways.

Everyone is doing it, so I'm doing it too: #Java30WithIntelliJIDEA www.jetbrains.com/lp/java-30/i... Funny that I came out as IDE skeptic...

JFR is getting a new method sampler that walks stacks at safepoints in JDK 25. Learn all about the new sampler in this week's blog post: mostlynerdless.de/blog/2025/05...

And in what outfit are you giving your talks?

In this weeks blog post I'll show you how develop and run a CAP Spring-Boot Java app locally on your Android phone using Termux and VSCode: mostlynerdless.de/blog/2025/05...

The good old days of console apps on your phone, it even supports touch:

I'll be speaking with David Kiefer next Wednesday on writing Linux schedulers in Java at #JUG #Karlsruhe: jug-karlsruhe.de/content/soun... Come by to see the first idle game scheduler in action (a scheduler where you yourself schedule the tasks in form of a cookie clicker style game)

If you're running Java applications on cloudfoundry, have a look at the Java plugin for the cf cli, which allows you get heap-dumps and thread-dumps and profile your application (cc @openjdk.org): github.com/SAP/cf-cli-j... I just released a new version, looking forward to any feedback.