jdk

Set up JDK Mission Control with Red Hat Build of OpenJDK

Set up JDK Mission Control with Red Hat Build of OpenJDK

JDK Mission Control is now the newest member of the Red Hat Software Collections (RHSCL). JDK Mission Control is a powerful profiler for HotSpot Java virtual machines (JVMs) and has an advanced set of tools that enable efficient and detailed analysis of the extensive data collected by JDK Flight Recorder. The toolchain enables developers and administrators to collect and analyze data from Java applications running locally or deployed in production environments using OpenJDK 11.

In this article, I will go through a primary example of setting up JDK Mission Control. For Linux, JDK Mission Control is part of the RHSCL and, for Windows, it is available as part of the OpenJDK zip distribution on the Red Hat Customer Portal.  For Linux, these instructions assume that Red Hat Build of OpenJDK 11 is already installed. I will show how to set up the system to install software from RHSCL, which provides the latest development technologies for Red Hat Enterprise Linux. Then, I will install the JDK Mission Control and run a simple sample application. The whole tutorial should take fewer than 10 minutes to complete.

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Eclipse for JNI development and debugging on Linux (Java and C)

selection_166Cross language development in one project

In this tutorial style article I’ll discuss how to configure Eclipse for Java Native Interface (JNI) development based on a sample project that you can copy and modify. I.e, you can have a single project that can be both Java and C at the same time, and support a full code navigation and debugging of both languages.

This article is focused on the configuration of Eclipse rather than explaining JNI itself, however there are links to JNI literature at the end.

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Dude, where’s my PaaS memory? Tuning Java’s footprint in OpenShift (Part 2)

Continued from part 1.

The test web service

The test web service implements a simple file cache storing up to 10 copies of any given named file. Uploading copies beyond the 10th one causes the oldest version to be discarded. The server supports a variety of requests allowing

  • a new version of a file to be uploaded
  • an existing file version to be downloaded
  • listing of the name and version counts of all files in the cache
  • deletion of all copies of a named file
  • deletion of the whole cache

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Dude, where's my PaaS memory? Tuning Java's footprint in OpenShift (Part 1)

Is Java really greedy for memory?

Java is often blamed for being an over-hungry consumer of physical memory. Indeed, until recently our OpenShift team were tempted to draw this same conclusion. OpenShift is Red Hat’s open source Platform as a Service (PaaS) product. You can access it via public Cloud infrastructure managed by Red Hat (OpenShift Online) or even deploy it to your own data centre/private cloud (OpenShift Enterprise). OpenShift Online provides simple and manageable scalability to anyone developing and deploying web services. One of the OpenShift team’s goals is to maximize the number of guest Java EE deployments on any underlying physical host. However, in the first release of OpenShift meeting this goal was challenged by the high physical memory use observed in many of the deployed JVMs. With only so much memory available on any given physical host the more memory each JVM uses the lower the density of guest deployments.

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