IJ55734: BUSY HANG IN GETANDSETOBJECT

APAR status

• Closed as program error.

Error description

• Error Message: An increase in cpu consumption and one or more
  threads hung in method getAndSetObject from the sun.misc.Unsafe
  package was noted.
  .
  Stack Trace: Various stacks are possible depending on where
  getAndSetObject is called from when the problem occurs.
  .
  

Local fix

• The problem can be avoid with the following JVM command line
  argument:
  -Xjit:dontInline={*/misc/Unsafe.get*}
  

Problem summary

• An error introduced into createUnsafeGetWithOffset can result in
  incorrect optimization of the unsafe get* methods.
  getObjectVolatile is used in getAndSetObject, and the incorrect
  optimization resulted in the method being unable to exit the
  loop. The problem was introduced in openj9-0.47.0, mid 2024.
  

Problem conclusion

• The JVM has been corrected to fix the error in
  createUnsafeGetWithOffset by
  https://github.com/eclipse-openj9/openj9/pull/22249
  .
  This APAR will be fixed in the following Releases:
  .
  IBM Semeru Runtimes
   21 21.0.9.0
   21 21.0.9.0
   17 17.0.17.0
   11 11.0.29.0
  IBM SDK, Java Technology Edition
   8 SR8 FP51 (8.0.8.51)
  .
  Downloads and supplementary documentation can be found at the
  following locations:
  - For non z/OS operating systems:
   - IBM Semeru Runtimes, Version 11 and later
   https://www.ibm.com/semeru-runtimes/downloads/
   - IBM SDK, Java Technology Edition, Version 8
   https://www.ibm.com/support/pages/java-sdk-downloads/
  - For the z/OS operating system:
   - Java SDK Products on z/OS
   https://www.ibm.com/support/pages/java-sdk-products-zos
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  JIT

• Fixed component ID

  620700124

Applicable component levels