banner
LightNews
mostlynerdless.de
Johannes Bechberger
@mostlynerdless.de
630 followers 96 following 140 posts
OpenJDK hacker at SapMachine, works on hello-ebpf for fun
Posts Media Videos Starter Packs
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · 4d
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...
JFR and Equality: A tale of many objects - Mostly nerdless
Learn how to compare objects from JFR recordings in Java and why this is slightly trickier than you might have expected.
mostlynerdless.de
1 1
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · 8d
Oh, I'll take a look this afternoon/tomorrow afternoon
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · 18d
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...
Silencing JFR's Startup Message - Mostly nerdless
Learn how to disable the JFR startup messages and why you see them even with the default warning logging level.
mostlynerdless.de
Reposted by Johannes Bechberger
scylladb.com
ScyllaDB @scylladb.com · 22d
💪 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
2 2 6
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · 21d
I had a great recording session yesterday with Jake, we hope you like our chaotic talk
1 1
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · 25d
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...
How to waste CPU like a Professional - Mostly nerdless
In this week's blog post, you'll learn seven different ways to waste a specific amount of CPU-time. Number seven will surprise you.
mostlynerdless.de
1 2
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · 26d
Turns out this is not possible.
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · 26d
The new CPU-time profiler is truly powerful. You can even write a configurable wall-clock profiler with it on Linux (guess what I'll show in a follow-up blog post).
1
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · 27d
The rationale was: Almost nobody uses a different platform in production (and test environments) anyway, so it's not worth the hassle to spend years implementing it on other platforms.
1
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · 27d
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
Java 25's new CPU-Time Profiler (1) - Mostly nerdless
Learn all about Java 25's new CPU-time profiler and why it matters in this weeks blog post from the creator himself.
mostlynerdless.de
1 7 12
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · Sep 9
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...
Profiling with the Cloud Foundry CLI Java plugin - Mostly nerdless
Learn all about profiling with our CF CLI Java plugin and all the other awesome features to make your life easier.
mostlynerdless.de
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · Sep 1
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.
Java 25’s new CPU-Time Profiler: Removing Redundant Synchronization (4) - Mostly nerdless
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 blog post.
mostlynerdless.de
1
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · Aug 30
I got your mail, just didn't get around to replying. I'll take a look next week.

But in general, I would say that it's probably fast enough. There are other areas in the JVM that have probably more potential for optimization (cc @shipilev.bsky.social)
2 1
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · Aug 27
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...
Java JFR Profiler - IntelliJ IDEs Plugin | Marketplace
An open-source profiler plugin for JDK 11+ based on JFR, async-profiler and Firefox Profiler. This plugin supports profiling your Java applications directly in...
plugins.jetbrains.com
1 2 4
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · Aug 26
One of my colleagues thought it was giving people too many reasons not to switch to JDK 25 :D
1 3
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · Aug 25
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...
Java 25's new CPU-Time Profiler: Queue Sizing (3) - Mostly nerdless
Learn everything you didn't want to know about sizing the sampling queue in JDK 25's new CPU-time profiler.
mostlynerdless.de
2 2
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · Aug 22
Sneak peek into my upcoming blog post:
Plot of sample loss and memory consumption vs queue size in the new CPU-time sampler of JDK 25
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · Aug 11
Thanks for the reminder :)
1
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · Aug 11
Neither did I. Hope so see someplace else.
1
Reposted by Johannes Bechberger
scylladb.com
ScyllaDB @scylladb.com · Aug 7
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
Hello eBPF: Concurrency Testing using Custom Linux Schedulers
How anyone can write a basic Linux scheduler and use it, for example, to fuzz for concurrency bugs or optimize for specific workloads.
www.p99conf.io
1 4
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · Aug 6
So more time for other pastimes this autumn.
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · Aug 6
Seems like I won't be part of the great Devoxx Belgium conference this year.
1 2
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · Aug 4
TIL: the k3s uninstall script changes the hostname
1
mostlynerdless.de
Johannes Bechberger @mostlynerdless.de · Jul 30
Don't miss the first article of the series: mostlynerdless.de/blog/2025/06...
Java 25's new CPU-Time Profiler (1) - Mostly nerdless
Learn all about Java 25's new CPU-time profiler and why it matters in this weeks blog post from the creator himself.
mostlynerdless.de
1