In this episode of the Foojay Podcast, we're bringing you something special: a full batch of hallway-track conversations recorded live at …
Learn you how develop and run a CAP Spring-Boot Java app locally on your Android phone using Termux and VSCode.
Ever wonder how the JDK Flight Recorder (JFR) keeps track of the classes and methods it has collected for stack traces and more? In this …
Learn about the rise and fall of the onjcmd Java debugger feature, from its inception to its eventual removal.
Have you ever wondered how libraries like Spring and Mockito modify your code at run-time to implement all their advanced features?
Learn about new support for XDP to create a simple package blocker for eBPF.
This week we generate the C code for struct and map definitions automatically, using annotation processors to simplify writing programs.
Let's look into the eBPF memory layout and alignment of structs transferred between the kernel and user-land.
I went traveling again, read more on my travels to FOSDEM, Canada and Zurich in February/early March in this travel report.
This week I'll implement ring buffer support in my eBPF library and explain how ring buffers are used in eBPF.
Learn why using libbcc is not the best idea and start working with the newer libbpf.
This week, we use tail calls and create our first application using hello-ebpf as a library.
We run benchmarks to see whether JDWP's onjcmd features improves the debugging performance.
How to use another kind of eBPF maps, the perf event buffer, and run tests with docker and JUnit 5.
This week we'll add support eBPF maps to hello-ebpf to communicate between eBPF program and userland Java programs.
eBPF allows you to attach programs directly to hooks in the Linux kernel without loading kernel modules, like hooks for networking or …
2023 was an adventurous year for me: I came into my blogging rhythm, blogging every one to two weeks, resulting in 39 articles, many of them …
Learn about the website that gives an overview of JFR events, with descriptions from the OpenJDK, their properties, examples, …
The Foreign Function & Memory API (also called Project Panama) has come a long way since it started.
Or: I just released version 0.0.11 with a cool new feature that I can't wait to tell you about...
The ability to disconnect and then reattach debuggers is helpful for many complex debugging scenarios and can help you debug faster.
I was searching for some JFR-related settings on the internet when I stumbled upon the /jfr command that exists in Minecraft...
Find out how JFR allows you to implement your events to record custom information directly in your profiling file.
I had an epiphany: Aren't virtual threads with Loom just a version of HyperThreading on the JVM?
Have you ever wanted to bring your JFR events into context? Adding information on sessions, user IDs, and more can improve your ability to …
Collaborating with other people from different companies in an Open-Source project is great.
Learn about onthrow and onjcmd and more that can improve the performance of on-demand debugging, as this allows us to trigger the start of …
Between 2nd and 17th September, I gave three talks in three different cities!
Disabling C2 can be an option to speed up builds of smaller Java applications in CI systems, mainly when restricted to one or two CPU cores.
Erik Österlund summed up the problems with my previous JEP proposal quite nicely, and here are my responses!
This article is the first of two articles covering the draft of a new iterator-based stack walking API, which builds the base for the …
Have you ever wondered how safepoints are implemented in the OpenJDK? Follow me down the rabbit hole into the inner workings of the JVM.
Go out, visit the world, have friends, and read my blog post on flame-graph construction mid-next week.
jtreg is the test harness used by the JDK test framework. Attaching a debugger cumbersome to enable debugging in VSCode. But worry no more!
I spoke in two weeks in 3 countries, 4 cities and 5 different venues. This is my report on the trip. Check it out!
Understanding class loader hierarchies is essential when developing instrumenting Java agents. So I wrote an article about it.
How to use the WhiteBox API and Compiler Directives to get control of the JIT for better profiling of API tests!
AP-Loader wraps async-profiler and its tools with an API in a cross-platform JAR. This article is about the API.
Using AsyncGetCallTrace from a separate sampler thread is possible and this article tells you why and how!
Ever wondered how to find classes and dependencies that you don't actually use? Here I describe how to implement an instrumenting Java …
How to develop a tiny Java profiler, that can output flame graphs, in just 240 lines of pure Java, making it easy for anyone to understand.
Ever wondered why you need design patterns and how to apply them? Miroslav Wengner's book has you covered.
AsyncGetCallTrace is the base of many profilers, but how can we test it automatically to make sure it's correct? I'll explore a layered …
Do you trust profilers? I once did too. Here I describe why you should take the results of profilers with a grain of salt.
Let's talk about debugging and observability. We work with debugging all the time, but how well do we know this common practice?
Did you ever wonder whether JFR timestamps use the same time source as System.nanoTime? Come down the rabbit hole with me!
Ever wondered how to use Firefox Profiler to view your own profiling data? This article gives you the foundations!
Ever wanted to profile your application directly from your IDE? Here comes the Java JFR Profiler plugin, an open-source plugin for IntelliJ!
An introduction into GetStackTrace, AsyncGetCallTrace, and the history and specification of AsyncGetStackTrace.
How do profilers like async-profiler work? How to write your own? This is the second part, covering wall-clock profiling.
How does debugging work under the hood? This article explains the basics of JDI and JDWP and gives the JDWP packets for an example program.
How do profilers like async-profiler work? How to write your own? This series tries to write a tiny sampling-based profiler from scratch!
Ever wondered what all the JDK Flight Recorder events are? Wonder no more, https://sapmachine.io/jfrevents is here to help you.
Using async-profiler can be quite a hassle, especially when trying to use it in a library. The new ap-loader project tries to fix this!
When I ask Java devs whether they profile, the answer is usually "no". A reason is the lack of info and knowledge for everyday developers.
