Eclipse OpenJ9

Welcome to the user documentation for the Eclipse OpenJ9 virtual machine (VM).

This user documentation supports the configuration, tuning, and diagnosis of the OpenJ9 VM in an OpenJDK runtime. However, due to differences between the Java SE class libraries, specific options might apply only to one Java SE version. Icons are used to indicate where differences apply. For example:

Start of content that applies only to Java 8 (LTS) This sentence applies only to Java 8 binaries that include the OpenJ9 VM. Icons for LTS releases are this colour. End of content that applies only to Java 8 (LTS)

Start of content that applies only to Java 10 and later This sentence applies only to Java 10 or later binaries that include the OpenJ9 VM. Icons for feature releases are this colour. End of content that applies only to Java 10 or later

To see which Java releases are LTS releases and which are feature releases, and for information about release cadence, supported platforms, and build environments, see Supported environments.

Note: Documentation to support OpenJ9 is still under construction. The current content covers some high level information about OpenJ9 components together with the command-line options and environment variables that you can use to configure the VM when you start your application. We expect further content to be contributed over time. Because OpenJ9 was contributed to the Eclipse Foundation by IBM, this content contains some links to additional information that forms part of the IBM® SDK, Java™ Technology Edition product documentation in IBM Knowledge Center. That content supplements the documentation here until a more complete set of user documentation is available.

We welcome contributions to the user documentation. If you would like to get involved, please read our Contribution guidelines. If you spot any errors in the documentation, please raise an issue at our GitHub repository.

Supported environments

OpenJDK binaries that contain the OpenJ9 VM are supported on a range of hardware and operating systems. This range is expanding as work progresses at the Eclipse foundation. See the current list of supported environments for details.

Note: This user guide contains information about configuring, tuning, and debugging OpenJ9 on the z/OS® platform. This content was contributed by IBM so that it is available when the work to create OpenJDK binaries for the z/OS platform is complete.

You can obtain pre-built OpenJDK binaries from the AdoptOpenJDK project: