JVM

Episode 91. OracleJDK? OpenJDK?, Zulu? Corretto? So many!

So just in case you didn’t know, but being a Java developer is as fun as ever! The ecosystem has been changing from the past year, and today, we have “tons” of Java Developer Kits to choose from. Want to know what happened? And want to know how different they are? (or what do they bring to the table), then tune in!

In this episode we cover the history of OpenJDK, and uncover the reason of why there are many JDKs out there. We dive in some of the licensing terms (hint. If you are using Oracle JDK 8, make sure you are getting security updates on with a support plan!).

Then Bob dives into some very fun differences between OpenJDK, Azul, and OpenJ9… and the tool to “keep sane” with all these installations, SDKMan! So if you do Java development for a living (and even if you are a hobbyist) this episode explains all the different Java versions you can play with!

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Episode 86. Move Over Slow Startup times, GraalVM…IS…HERE. (and cross-language support, and less memory footprint…)

Oh my! This episode is going to be one of our favorites. There are times where the Java ecosystem delivers something incredibly interesting (InvokeDynamic, Lambdas, Streams, Kotlin), and this episode is one of those! You may have heard it mentioned around the interwebs or conferences (this new GraalVM thing)… well, it’s here to stay and is propelling JVM languages to a whole new level of interoperatibility and performance!

So GraalVM at the very high-level view is a “Java Virtual Machine” (in reality there’s much more to it, but we can at least start there). It provides tons of interesting features, like the ability to not only compile Java/JVM languages, but also Javascript, LLVM Languages (like C++), Python, R (and is expanding to others), and more importantly, interoperatibility between all these languages.

But the bee’s knees (or the most interesting fact) is that GraalVM also have the “Native Image”, which allows you to completely bake in a Linux (more platforms coming) binary straight up from your source code. The Native Image doesn’t require Java to be installed, and you can start your application as you would any other Linux executable. The most impressive part? Startup times are incredibly fast!

So we have usually addressed tons of misinformed myths of the Java language like “It’s slow:” (No, not really), or “You can code more performant code in C++” (possibly, but you have to be an expert to squeeze more performance than the JVM’s JIT compiler). But one area that the claim has held true is that “Java has slow startup times”. And (it used to be) true! Because of the dynamic classloading that Java supports, it’s very hard for the JVM to startup fast. For long running applications this is usually not a problem, even so, for the new Cloud folks (and Lambdas, and AutoScaling Groups), fast startup time is a “thing”. And so, with GraalVM (with some caveats) we are conquering one of the last arguments against the JVM languages.

In all, THIS is the episode to listen this year. It’s exciting, new technology that we could really spin up and use. Let’s have fun programming again with GraalVM.

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We thank DataDogHQ for sponsoring this podcast episode

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Episode 85. Monitor the World with JMX!

There are technologies that sometimes are forgotten in a lonely corner, but that actually are quite sturdy. One of these is the All-Powerful Java Management Extensions (also known as JMX). With JMX you can actually expose a lot of metrics of your application and TONS of libraries use it “out of the box”. Libraries like Tomcat, JVM, ActiveMQ, Spring (and ton others) exposes their metrics through JMX. And you can too!

In this episode we go over how to both consume JMX metrics (through JConsole, or statsD, or other Performance Monitoring Tools), and how to produce them as well (By creating your own MBeans), not only that, but we also go with how to be able to “invoke” these on a live application. Have you ever wanted to say “Oh my, I wish I could call this method while the program is running in production ‘At will'”. Well, with MBeans, you can make that happen! Not only that, but if you really want to you can also expose your MBeans through a Rest Endpoint with Jolokia.

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We thank DataDogHQ for sponsoring this podcast episode

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We also thank OverOps for sponsoring this podcast episode

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Episode 50. How many Classes would a ClassLoader Load if the ClassLoader was Loading the parent Classes?

You worked with them “all the time”, whenever you know it or not! Classloaders are the little workers that make sure all the code is there and ready to be executed. Bob revisits this topics and goes into more detail on how the ClassLoading hierarchy works, when to watch out, and how different frameworks (OSGI, and Java EE containers) may be configured to load classes. If you have run into “ClassNotFound” exceptions, this can help you explain why!

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