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; monetary, 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.

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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 0.41.0 released

November 2023

We're pleased to announce the availability of Eclipse OpenJ9 v0.41.0.

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:

The -XX:+CompactStrings option is now enabled by default on Java 11 and later.
The JITServer client can now use the JITServer AOT cache even if both the -Xshareclasses:readonly option and the JITServer AOT cache feature were enabled at the same time. With the change in behavior of the -Xshareclasses:readonly option, the shared class cache startup creates a temporary new (writable) top layer that the JITServer AOT cache can use to store data that it needs to function.
A new -XX:[+|-]EnableDynamicAgentLoading option is added to enable or disable the dynamic loading of agents into a running VM.
A new -XX:[+|-]UseZlibNX option is added to control the loading of the zlibnx library in the LIBPATH environment variable on AIX® systems.
Support is added for the com.sun.management.ThreadMXBean.getThreadAllocatedBytes() API on all platforms except z/OS®. In the coming future z/OS release, the support for this API will be added on z/OS platforms as well.

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

Performance highlights include:

Performance of algorithms with the use of OpenSSL version 3 and later is now enhanced. Improved algorithms include SHA256, AES, HmacSHA256, and ChaCha20.
To obtain these improved algorithms and further enhance the performance of these algorithms on Linux® and AIX, use OpenSSL 3.0.12 or a later 3.0.x version, or 3.1.4 or a later 3.1.x version.
For Java 17, the performance to call virtual or interface methods through MethodHandles is improved.
The JIT inlining optimization is enhanced to improve performance when it selects methods with constant arguments.