What's new in version 0.49.0

The following new features and notable changes since version 0.48.0 are included in this release:

Features and changes

Change to the shared classes cache generation number

The shared classes cache generation number is incremented. The increment in the shared classes cache generation number causes the VM to create a new shared classes cache, rather than re-creating or reusing an existing cache.

To save space, all existing shared caches can be removed unless they are in use by an earlier release. For more information, see Housekeeping and -Xshareclasses.

The shared classes cache generation number is modified because of a change in the format of ROMClasses that are stored in the shared classes cache. A new flag J9AccClassIsShared is added to ROMClasses to indicate whether a ROMClass was loaded from a shared classes cache or from a VM.

New shared classes cache suboption added to adjust the number of startup hints that can be stored

You can use the -Xshareclasses:extraStartupHints=<number> option to adjust the number of startup hints that can be stored in a shared cache. By default, you can store only up to 64 startup hints in a shared cache.

For more information, see -Xshareclasses:extraStartupHints.

The VM can use compressed references to decrease the size of Java objects and make better use of the available space in the Java heap. You can now control the compressed reference allocation with the following options:

For more information, see Compressed references.