New toy, "residence graphs": tracking the compilation level for top method in the stack. On the left, normal JIT mode: compilers are busy, intp -> T2 -> T3 code is hot; T4 code slowly takes over. On the right, normal AOT+JIT (Leyden) mode: AOT code carries most of it, JIT happens to plug the holes.

"Method Tracing" in async-profiler: github.com/async-profil...

SIMD Within a Register: How I Doubled Hash Table Lookup Performance Learned about SWAR the first time in the one-billion row challenge. Nice explanation including benchmarks.

youtu.be/q4mRNu6_lpc C++ debugging, -Og, safepoints, adr sanitization. kefir (from scratch C compile), SCCP in Simple, graph DSL. Strict aliasing, implicit conversions. Pointer comparison. GPU Kernels DSLs (Triton, Gluon, TLX), Object layout, NUMA. Distributed random forest

Nice usage of #zstd for tarball via Kelly Sommers on Twitter. x.com/vmg/status/1...

📝 Blogged: "Let's Take a Look at... Lower Java Tail Latencies With ZGC" As #Java 25 got released earlier this week, I took the ZGC garbage collector for a spin, exploring how it lives up to its promise of sub-millisecond GC pause times. 👉 www.morling.dev/blog/lower-j...

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

What Makes System Calls Expensive: A Linux Internals Deep Dive. blog.codingconfessions.com/p/what-makes... Another great post by @abhi9u.bsky.social. I learned a lot, including vDSO.

JChateau our Unconference organized in France in the area of the Châteaux of the Loire Valley is open for registration at : www.jchateau.org/registration...

Java 25 / JDK 25: General Availability: mail.openjdk.org/pipermail/jd... Features: openjdk.org/projects/jdk... Downloads: jdk.java.net/25/ #Java25 #JDK25 #OpenJDK #Java

Oracle detaches #GraalVM from the Java SE train 👀 • JDK 24 = last with Graal JIT / GraalVM in Java SE • Native Image discontinued for #Java SE (-> Leyden) • GraalVM team pivots to non-Java (GraalPy, GraalJS) 👉 Java devs: migrate to C2 JIT & track Leyden AOT work blogs.oracle.com/java/post/de...

youtu.be/5YIhnjThoK4 Burning Man, boats diving between dust devils. LSP, C backend, debug info, codegen , zydis, ASM. Ryan/quxlang update - literal types, bitwise operators, keywords, functions, containers. LLVM LogicalResult. GCC and LLVM funding, Triton, Cuda, ML , Mojo

Let's Take a Look at... JEP 483: Ahead-of-Time Class Loading & Linking! buff.ly/vXDtFq9 #Java #jdk #jep483

The date have been confirm to 04-08 march 2026, registration will open soon

🎓 JEP 523 moved to candidate Title: Make G1 the Default Garbage Collector in All Environments Type: feature Component: hotspot / gc See openjdk.org/jeps/523

The xCapture and xtop eBPF tools are now in beta, with a demo dataset! With a pre-recorded xcapture dataset from my dev server, now you can play with xtop "thread activity sampling" drilldown even on your laptop, without having to run xcapture yourself! (link in replies :-)

#java JEP 401 on value classes is submitted : openjdk.org/jeps/401

youtu.be/qhfhluIory0 C++/11,20,26; partial -g code; Java vs C++ speed with debugging. x86/arm vs java mem model. x86 intrinsics in Java. LSPs. C++ vs Java containers. Compile-time alloc size. UI frameworks. Teaching programming via games. C++ default copy/move opers

Tried to give an introduction on the class file API that explains it to anybody working with Java: vimeo.com/1115458585 Courtesy of JavaZone. Thanks for having me.

#Shenandoah: Implement efficient support for object count after gc events "JFR supports ObjectCountAfterGC events that provide a histogram of extant classes in the heap by size and count following each GC. This event isn't implemented for Shenandoah GC." bugs.openjdk.org/browse/JDK-8...

A day worth of massaging Leyden into training with slower/optimizing compiler and delegate the untrained compilations to faster/not-that-optimizing compiler at runtime. This would be nice to replace all those -XX:TieredStopAtLevel=1 suggestions for much more efficient config.

Interesting update in this "Leyden Early Access 2 Release" page on what Project Leyden is about to deliver in Java 25 and what may come later.

Something for Linux block I/O nerds - Linux Storage Stack Diagram (up to kernel v6.16) published: www.thomas-krenn.com/en/wiki/Linu...

🎓 JEP 522 moved to candidate Title: G1 GC: Improve Throughput by Reducing Synchronization Type: feature Component: hotspot / gc See openjdk.org/jeps/522

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...

What if I told you that now it's possible to see inside hardware interrupt handling activity, even without PMU access on cloud VMs, without tracing or slowing anything down? Thanks to passive sampling with eBPF, task iterators and some pointer chasing, this is now a thing 😎

youtu.be/wTHBUyLrBkg C++ copy/move constructors; oper overloading semantics; primitives as defined in stdlib or built-in; All About Register Allocation (SSA chordal graph property; graph-color vs linear scan)

New Tool: xstack - Completely Passive eBPF Linux Stack Profiling Without Any Tracepoints tanelpoder.com/posts/xstack...

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...

youtu.be/Std-folefRs List of Cliff talks. Blockchain vs law. 10 hours LLVM setup, lldb, VSCode, Bazel bugs, Autosave, AI. Facebook Php to Hack. Repl, eval, JIT-per-GPU, tiered compiles. Twitter war story. Register & inline keywords, Simple/SoN on MLIR, MOJO self host

And don't miss the equally amazing part 2: www.datadoghq.com/blog/enginee...

Fantastic new blog post from my colleague Nayef. If you're into Go internals, check it out! www.datadoghq.com/blog/enginee...

It’s been a while, had to look at JVM logs, and found that ChatGPT doesn’t know very well JVM unified logging. Fortunately, I wrote a blog post based of JVM 11 a while ago. That gives better clue on what to do what to look for. blog.arkey.fr/2020/07/28/e...

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...

How Does the Memory Management Unit (MMU) Work with the Unix/Linux Kernel? open.substack.com/pub/chessman...

Performance measurements… and the people who love them

✏️ JEP 8359802 was drafted Title: Ergonomics Always Select the G1 Garbage Collector as Default Type: feature Component: hotspot / gc See openjdk.org/jeps/8359802

youtu.be/F6pC84rT2OE Simple update, Logging (for debugging, perf, h2o debug, rust serde, microservices dep graph discovery). Modules in Simple, classfile approach, imports, headers Dependency management: fetch vs Build, Imports, resolution, lock files

Loom project landed some preliminary info on custom "scheduler" (currently an `Executor`) for virtual threads ``` Thread.ofVirtual().scheduler(pool) ``` github.com/openjdk/loom...

From Norman Maurer on Twitter : Nice writeup from the author of #phkmalloc as well .... Thanks to @chvest for sharing with me phk.freebsd.dk/sagas/phkmal... #malloc

Why You Can't Directly Move Data Between Two Memory Addresses in x86 Assembly and How to Do It open.substack.com/pub/chessman...

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:

youtu.be/bm5KfbGa_H4 Quxlang, number literal highlighting & precedence, Simple update, Generics in Quxlang, composition over inheritance, Impl vs interface inheritance. All About Equals, ==, eq, &a==&b, user-defined

github.com/netty/netty/... This is only needed for 4.1.x, in 4.2.x we are able to fix this in another way that does not require the usage of sun.misc.Unsafe

What's new in JDK 25 on the JDK Flight Recorder. From Erik Gahlin egahlin.github.io/2025/05/31/w...

🎯 JEP 521 updated to target JDK 25 Title: Generational Shenandoah Type: feature Component: hotspot / gc Release: 25 See openjdk.org/jeps/521

🎯 JEP 509 proposed to target JDK 25 Title: JFR CPU-Time Profiling (Experimental) Type: feature Component: hotspot / jfr Release: 25 See openjdk.org/jeps/509