Our Story

Eclipse OpenJ9 is a high performance, scalable, Java virtual machine (JVM) implementation that represents hundreds of person-years of effort. Contributed to the Eclipse project by IBM, the OpenJ9 JVM underpins the IBM SDK, Java Technology Edition product that is a core component of many IBM Enterprise software products. Continued development of OpenJ9 at the Eclipse foundation ensures wider collaboration, fresh innovation, and the opportunity to influence the development of OpenJ9 for the next generation of Java applications.

Our supporters

The success of the OpenJ9 project is underpinned by the generosity of our supporters, to whom we would like to extend our thanks. This support comes in different forms; monetory, people, system, and data center resources. People resources help us to staff the planning, development, delivery, and support of OpenJ9 releases as well as pioneering new and innovative technologies. Dedicated systems and hosting services allow us to run automated build and test operations, which help ensure that quality and reliability is central to all our deliverables.

Join the conversation

Join us on Slack where you can ask questions and chat directly with our developers. Whether you simply have a question about using OpenJ9, an idea for improvement, or a problem you want to discuss, we'd love to hear from you.

Join OpenJ9 Slack

Like all great open source projects, we have a vibrant and busy GitHub repository where you can create issues to explore ideas, request new features, or report any difficulties you are having.

See OpenJ9 Issues

Participate in the Eclipse OpenJ9 project

Become a contributor

We welcome contributions to the project in all shapes and forms. If you are interested in JVM development, we'd love to hear your ideas and help you collaborate with us on the code base. There are other ways you can contribute too, such as working on our website and docs. Be a part of the project and share in our success!

Contributor Guide

Join community calls

Our regular calls are a great place to find out what is going on in the project. As well as discussing our release plans and development status, we often feature lightning talks by members of the community. For example, technical deep dives or overviews about new features. To see agendas and recordings, look in the Slack #planning channel.

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Eclipse OpenJ9 version 0.38.0 released

May 2023

We're pleased to announce the availability of Eclipse OpenJ9™ v0.38.0.

This release supports OpenJDK version 8, 11, and 17. For more information about supported platforms and OpenJDK versions, see Supported environments.

Other updates in this release include the following:

New -XX:[+|-]HandleSIGUSR2 option is added to enable the handling of the SIGUSR2 signal by the application signal handler instead of the VM signal handler in the absence of signal chaining.
Support for the Checkpoint/Restore In Userspace (CRIU) tool is currently provided as a technical preview. This preview is supported for use in production environments, however, all APIs and options are subject to change. You can use the CRIU feature to stop the VM at a checkpoint, save its state, then run the VM from the point where it was stopped, hence improving the VM startup time and performance.

To read more about these and other changes, see the OpenJ9 user documentation.

Performance highlights include:

Stack walking for refreshing the latest user defined ClassLoader (LUDCL) cache is optimized, saving a substantial amount of CPU time for applicable workloads.

Eclipse OpenJ9 version 0.37.0 released

OpenJ9 v0.37.0. release supported OpenJDK version 19. OpenJDK 19 was out of support at the time of the 0.37.0 release. Builds of 0.37.0 should not be used in production and contains known security vulnerabilities as of 18 April 2023.

Other updates in this release include the following:

The OpenJ9 ThreadMXBean interface extends the com.sun.management.ThreadMXBean interface instead of the java.lang.management.ThreadMXBean interface.
OpenJ9 now supports the use of an extra attribute, tokenlabel, in the SunPKCS11 configuration file on z/OS® and Linux on IBM Z to assign a label to a PKCS#11 token. The tokenlabel attribute can be used instead of the slot or slotListIndex attributes.

To read more about these and other changes, see the OpenJ9 user documentation.

Performance highlights include:

With the implementation of CRC-32C polynomial acceleration on Linux on POWER LE (ppc64le) and AIX POWER® BE (ppc64), performance of CRC-32C calculations on these platforms is 25 times faster (even up to 42 times faster) on data payload of typical sizes.