December 2016 - java-devroom - lists.fosdem.org

[Talk Proposal] Helping Linux and Java Play Well Together.
by Christine Flood 08 Dec '16

08 Dec '16

Abstract: Your Java method is compiled by Javac into an intermediate representation called bytecode stored in a .class file. That bytecode is fed to a JVM which can either interpret it one instruction at a time, or compile it into optimized machine code and execute that machine code. The mapping from method names to interpreted bytecodes or executing machine code is managed inside the JVM. This makes it difficult for Linux code analysis tools to display useful information about Java code. Generally you will receive an address for the executing code, but no mapping from the assembly code back to your Java program. Red Hat has developed two new tools to make it easier for Java programmers on Linux to see what their Java program is doing. The first is an unwinder for gdb which instead of giving addresses of compiled code, will actually show the names of the interpreted/compiled java methods. The second is an enhancement to perf that knows about Java class names and can map events like cpu instruction counts back to their associated Java methods. This way you can tell which of your Java methods is actually missing in the LLC or taking up 30% of your cpu time. Come see a demo of these tools at work. Christine H. Flood has been hacking programming languages and tools for over 20 years. She didn't really have much to do with the development of these tools but she thinks they are really useful and should be shown off.

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[Talk Proposal] Shenandoah: Why Do We Need Yet Another Garbage Collector?
by Christine Flood 08 Dec '16

08 Dec '16

Abstract: Garbage Collection (GC) liberates the programmer from having to call malloc and free. More importantly GC saves the programmer from having to debug their mistakes when using malloc and free. Unfortunately the details of how GC works are often a black box. This talk will start with a tour of all of the GC algorithms currently available in OpenJDK. We'll discuss how they work, their strengths and weaknesses, and which class of applications they were developed for. We'll work our way through serial gc, parallel gc, concurrent mark and sweep, and g1. We'll make the case for why we need all of them and just one more GC algorithm, Shenandoah. Shenandoah is a parallel and concurrent GC algorithm designed for applications with 100gb+ heaps and tight pause time constraints. It's the first GC algorithm targeting OpenJDK which compacts the live objects while the Java threads are running. We'll describe the algorithm itself, the implementation details, and the optimizations needed to achieve good performance. We'll present performance numbers and give a demo that visualizes Shenandoah. Bio: Christine H. Flood has been active in the programming languages community for more than two decades. She started work on Java Garbage Collection back when the JVM was just a reference implementation with a conservative garbage collector and she's had a hand in all of the existing OpenJDK algorithms. She's taken detours to do other things, but came back to the Java world to write just one more GC algorithm for Red Hat. Christine

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[Proposal] An unexpected journey among modules
by Remi Forax 04 Dec '16

04 Dec '16

Title: An unexpected journey among modules Abstract: So Java 9 has modules. As a member of the Expert Group, i've toured the french speaking JUGs to explain what Java modules are, and gather feeling and remarks from the community. One problem i face is that existing build tools like Maven or Gradle are updated at their own pace and are currently more focused on working on Java 9 than how to seamlessly support the new module environment (this is not a criticism they have a huge base of existing users). In a train after a presentation at one JUG, i flip out and start to develop my own build tool, pro (for programatic build tool) [1]. In this talk, i will explain why you have to compile several modules together even if the resulting module graph has no cycle, how a build tool can help you to test modules, how to integrate non modular jars from maven central and how to implement some vanity features like a plugin system, a REPL for creating the build configuration or use the new linker to create a static image. [1] https://github.com/forax/pro Bio: Remi Forax is Assistant Professor at UPEM (Paris East University), a Java Champion and an active participant of several OpenJDK projects. Moreover, he is/was member of several JCP expert groups that shape the recent versions of Java (invokedynamic, lambdas, modules). His research area focused on the implementation of dynamic languages on top of runtime environments, in that context, he is one of the maintainers of the open source project ASM, a bytecode instrumentation tool used by frameworks like Maven, Spring or Weld.

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Talk proposal: Three ideas for the G1 GC (and how to get involved)
by Erik Helin 04 Dec '16

04 Dec '16

Title: Three ideas for the G1 GC (and how to get involved) Abstract: The G1 garbage collector is currently proposed to become the default garbage collector in JDK 9. Recently three new ideas for G1 were described on the hotspot-gc-dev(a)openjdk.java.net mailing list: - parallel full GC - throughput write barriers - rebuilding remembered sets during concurrent mark This talk will present these three new ideas so that people who are interested in getting into G1 development know where to start, see what the existing code looks like today and highlight how one can contribute (it is not only about code!). The presentation can be made longer if people want to dive deeper into the details (but it can also fit in a 25 minute slot). Bio: Erik Helin is a developer at Oracle working in the Java group as a member of the JVM Garbage Collection team. For the past four years Erik has been working on the trace events framework, diagnostic tools for the Metaspace and for the last two years on the G1 garbage collector. Erik has worked on most parts of the G1 garbage collector and lately with a special focus on the policies. Erik is a reviewer in the OpenJDK JDK 9 project and a member of the hotspot OpenJDK group. I'm not yet sure if I recording the talk is ok, I'm still awaiting approval. Thanks, Erik

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Deadline extended!
by Mario Torre 01 Dec '16

01 Dec '16

Hi all! First of all, thanks a lot to everyone who already sent out a talk proposal, it's very appreciated! As you know the deadline is today, but I would like to extend it up to the 10th of December, to give more time to collect more proposals. I will send all the instructions and update the website accordingly tomorrow. Please, use this opportunity, it's likely we won't extend a second time! Cheers, Mario -- pgp key: http://subkeys.pgp.net/ PGP Key ID: 80F240CF Fingerprint: BA39 9666 94EC 8B73 27FA FC7C 4086 63E3 80F2 40CF Java Champion - Blog: http://neugens.wordpress.com - Twitter: @neugens Proud GNU Classpath developer: http://www.classpath.org/ OpenJDK: http://openjdk.java.net/projects/caciocavallo/ Please, support open standards: http://endsoftpatents.org/

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Talk proposal: Open J9 - The next Free Java VM
by Charlie Gracie 01 Dec '16

01 Dec '16

Title: Open J9 - The Next Free Java VM Abstract: For years IBM has developed an independent implementation of the Java Virtual Machine which helped foster rapid improvements in the Java ecosystem. Recently, IBM has open sourced language agnostic components such as IBM's JIT and GC technologies as part of the Eclipse OMR project. IBM is actively working to open source the rest of the J9 Java VM as the Open J9 project. I will discuss the different components of the Open J9 VM at a high level and our plans for creating the open source project. Bio: Charlie Gracie is currently working at IBM as the Garbage Collection Architect on the J9 Java Virtual Machine and as a Project Lead on the Eclipse OMR project. He has more than a decade of JVM development experience where he has mainly been focused on scalability. Recently he has also been looking into CRuby performance, getting back to his Smalltalk roots with SOM++ and working on creating the Open J9 project. Recording me on audio/video is acceptable under a CC-BY-2.0 license. Thanks Charlie Gracie

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