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What's new in version 0.30.0

The following new features and notable changes since version 0.29.0 are included in this release:

Features and changes

Binaries and supported environments

OpenJ9 release 0.30.0 supports OpenJDK 8, 11 and 17.

To learn more about support for OpenJ9 releases, including OpenJDK levels and platform support, see Supported environments.

Changes to the shared classes cache generation number

The format of classes that are stored in the shared classes cache is changed, which causes the JVM to create a new shared classes cache rather than re-creating or reusing an existing cache. To save space, you can remove all existing shared caches unless they are in use by an earlier release. For more information about the -Xshareclasses option, including the destroy options that you can use to remove caches, see -Xshareclasses.

Ignored options captured in java dumps

For improved compatibility with other Java implementations, OpenJ9 ignores many command-line options. If any were ignored, they are now listed in java dump files. For example, this command

java -Xdump:java:events=vmstop -XX:+UseCompressedOop -XX:CompressedClassSpaceSize=528482304 -version

would yield the following in the ENVINFO section after the complete list of all command-line arguments

2CIIGNOREDARG            -XX:+UseCompressedOop
2CIIGNOREDARG            -XX:CompressedClassSpaceSize=528482304

New -XX:[+|-]EnsureHashed option added

This option specifies/unspecifies classes of objects that will be hashed and extended with a hash slot upon object creation or first move. This option may improve performance for applications that frequently hash objects of a certain type. See -XX:[+|-]EnsureHashed for more details.

Known problems and full release information

To see known problems and a complete list of changes between Eclipse OpenJ9 v0.29.0 and v0.30.0 releases, see the Release notes.