Monthly Archives: November 2022

AP-Loader: A new way to use and embed async-profiler

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Using async-profiler can be quite a hassle. First, you have to download the right archive from GitHub for your OS and architecture, then you have to unpack it and place it somewhere. Or you get it from your OS distribution, hoping that it is the current version. It gets worse if you want to embed it into your library, agent, or application: Library developers cannot just use maven dependency but have to create wrapper code and build scripts that deal with packaging the binaries themselves, or worse they depend on a preinstalled version which they do not control.

java -jar ap-loader.jar profiler …; java -jar ap-loader.jar converter jfr2flame flight.jfr flame.html

I started the AP-Loader project to fix all this:

  • Want to run async-profiler? Just grab the latest loader JAR from GitHub, and run java -jar ap-loader-all.jar profiler regardless of your OS or architecture
  • Want to use the async-profiler as a Java Agent? You can use the loader JAR as javaagent and it behaves like the native async-profiler agent
  • Want to use jattach? java -jar ap-loader-all.jar jattach is your friend
  • Wondering what version of async-profiler you’re using? java -jar ap-loader-all.jar version has you covered
  • Want to use the converter to convert between formats? Just use java -jar ap-loader-all.jar converter
  • Want to use async-profiler in your library? Just add a dependency to the me.bechberger.ap-loader:-all-SNAPSHOT from the Sonatype OSS repository and use one.profiler.AsyncProfilerLoader.load()
  • Want to use the converter too? All the converter classes are included in the JAR, look no further than the one.profiler.converter package
  • Just want all this for one platform only? I build and package versions for all platforms. There can be multiple platform versions on the classpath
  • But what about the JAR size? It’s just under 800KB, so no worries

This project uses original binaries from async-profiler’s GitHub releases page and tests the resulting project using the original tests from async-profiler, so you can expect it to behave as async-profiler does. The idea for this project came up in a discussion with the creator of async-profiler, Andrei Pangin, in spring.

I use this project daily to profile my applications, so might you? I’m open to suggestions, bug reports and happy help to integrate ap-loader into your open-source library.

If I enticed you: Go over to GitHub to get more detailed information on this project.

This project is part of my work in the SapMachine team at SAP, making profiling easier for everyone. I built it to integrate async-profiler into more applications and libraries, like my upcoming profiler UI.

Overview of Java Profiling

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When I ask Java developers whether they do profile, the answer is usually “no”. The few that profiled before usually used VisualVM as a student and maybe JProfiler or YourKit years ago at work. One of the reasons for this is a lack of available information and thus knowledge for everyday Java developers.

This is a pity as profiling should be a part of the tool belt for every experienced developer (not just for Java). The problem is that most of the open-source profilers are targeted to the OpenJDK developers (or their colleagues), even if they won’t admit it. This can be seen in the lack of entry-level material on this topic and even the little that is out there is distributed across multiple conference websites, blogs, YouTube channels, and Twitter accounts.

A few months ago I started working on this topic and as a result, held a talk at the Java User Group Karlsruhe in the middle of October: It is an introductory talk answering the simple questions: Why should we profile? Which profilers to use? How to obtain and view these profiles? A recording can be seen on YouTube:

The gist of this talk is:

  • Why? Profiling helps you find the parts of your code that are slow and that are worth to be fixed.
  • Which and how? The consensus seems to be to use JFR or async-profiler with –jfrsync and JMC as a profile viewer.

While working on this talk, I collected a list of interesting conference talks on this topic:

This list includes talks on a variety of profilers, ranging from deep dives to overviews. Many of these talks and people were recommended elsewhere on the internet, on blogs, on Twitter, or in private conversations. Which I present in the following.

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