Service Refresh 6, Fix pack 5 is now available from the Downloads page.

This refresh includes the following updates:

  • New -Xshareclasses suboptions are available for creating layered caches, where a cache builds on another cache with the same name. You can use these suboptions to save space when you build a Docker container, for example.
  • You can use the new -Xshareclasses:noTimestampChecks option to turn off timestamp checking in shared classes.
  • You can use the new -Xshareclasses:noPersistentDiskSpaceCheck option to tell the VM to skip the disk space check that it usually runs when it creates a persistent shared classes cache.
  • You can use the new command line option -XX:+ClassRelationshipVerifier to record class relationships in the verifier, which avoids unnecessary class loading and reduces VM startup time.
  • Classes that are created by using the Unsafe.defineClass class are now stored by default in the shared classes cache.
  • -XX:+TransparentHugePage is enabled by default on Linux systems for POWER® and IBM Z® as well as x86 systems.
  • On 64-bit z/OS, -Xmso now has a 1 MB minimum value, to match the minimum stack space provided by the operating system.
  • A new exit dump agent is added, which shuts down the VM when the specified event occurs.
  • The ‘t’ and ‘T’ suffixes (indicating terabytes) are now supported for -X and -XX options that take a <size> parameter.
  • For compatibility, the following OpenJDK Hotspot options are now supported by OpenJ9: -XX:ParallelGCThreads, -XX:ConcGCThreads, -XX:ParallelCMSThreads.

For more information about these updates, see the Current news technote.

This refresh also contains fixes to the code base. You can find out more about these from our Fixes page.

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