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What's new in version 0.33.x

The following new features and notable changes since version 0.32.0 are included in this release:

Features and changes

Binaries and supported environments

OpenJ9 release 0.33.x supports OpenJDK 8, 11, 17, and 18.

OpenJ9 Windows® builds for OpenJDK 8 are now compiled with Microsoft® Visual Studio 2017. The Visual Studio redistributable files included with the build are updated to match.

Note: Binaries that are labeled 0.33.1 include additional bug fixes. For more information, see the release notes.

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

JITServer technology feature updated

The JITServer technology feature is updated to provide the following new capabilities, which are disabled by default:

  • The caching of AOT-compiled methods on the server. The AOT cache improves CPU usage when clients request the compilation of methods that were previously cached. Use the -XX:+JITServerUseAOTCache command line option to enable this feature.
  • The provision of metrics to a monitoring tool that follows the OpenMetrics standard. The following metrics are available for a JITServer server: CPU usage, available memory, number of clients connected, and number of active compilation threads. Use the -XX:+JITServerMetrics command line option to enable this feature.

Start of content that applies to Java 11 XL C++ Runtime required on AIX

AIX OpenJ9 builds now require version 16.1 of the IBM XL C++ Runtime. This was already required for OpenJDK 17 and is now also required from 11.0.16 to accommodate a security update to the HarfBuzz text shaping library.

Start of content that applies to Java 17 plus Linux reference compiler updated to gcc 10.3

Linux® builds for all platforms now use gcc 10.3 instead of gcc 7.5. See the list of build environments.

The maximum number of JIT compilation threads is increased

The maximum number of JIT compilation threads is increased from 7 to 15. If the JITServer feature is enabled, the maximum number of JIT compilation threads is increased further on the server, to 999. You can set the number of compilation threads to be used by specifying the -XcompilationThreads command line option.

Start of content that applies to Java 17 plus Default operating system stack size increased on x64 platforms

The default operating system stack size on Windows x64, macOS® x64, and Linux x64 platforms is increased from 256 KB to 512 KB to accommodate vector support. You can change the operating system stack size by using the -Xmso option.

Control groups v2 support

The Linux kernel has two variants of control groups (cgroups): v1 and v2. Many Linux operating systems are gradually transitioning from cgroups v1 to v2 as their default choice. Now, OpenJ9 has added cgroups v2 support, which is identical to the support for cgroups v1.

Support for OpenSSL 3.0.x

The JITServer technology feature now supports OpenSSL 3.0.x. For more information about OpenSSL support, see Cryptographic operations.

Known problems and full release information

To see known problems and a complete list of changes between Eclipse OpenJ9 v0.32.0 and v0.33.x, see the Release notes.