What's new in the OpenJ9 project

Eclipse OpenJ9 version 0.27.0 released

July 2021

We're pleased to announce the availability of Eclipse OpenJ9 v0.27.0.

This release supports OpenJDK version 8, 11, and 16. For more information about supported platforms and OpenJDK versions, see Supported environments.

In this release, the following new options are added and enabled by default to improve performance:

• -XX:[+|-]AdaptiveGCThreading dynamically adjusts the garbage collection thread count to reduce collection pause times.
• -Xgc:dynamicBreadthFirstScanOrdering enables a new scan mode to improve performance of the balanced garbage collection policy.

Existing option -XX:[+|-]GlobalLockReservation (AIX and Linux on Power systems only), which improves the performance of locking and unlocking of Java™ objects, is now also enabled by default.

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

Other performance highlights

• The performance of method invocation via reflection is improved by reducing stack walking overhead related to access checking associated with that API.
• The JIT compiler includes several incremental throughput improvements related to the warm hotness level and loop handling.
• On AArch64, the JIT compiler provides incremental performance improvements for applications generally, including: reducing Java synchronization overhead, improving array access performance in loops, and increased virtual and JNI method dispatch performance.
• New POWER10 hardware features are exploited to improve application path length and the performance of various array and byte operations.