IJ49741: UNEXPECTED NULLPOINTEREXCEPTION

APAR status

• Closed as program error.

Error description

• Error Message: Code runs successfully for a while then starts
  generating NullPointer exceptions. The location generating the
  exception may seem impossible for the object to be null. The
  method generating the exception will be running in the
  interpreter but if a JIT verbose log is taken or a system
  corefile analysed, it will be seen that the method has been
  compiled, likely multiple times.
  .
  Stack Trace: This is a rare problem that so far has only been
  reported for
  java.lang.invoke.BruteArgumentMoverHandle.permuteArguments(Brute
  ArgumentMoverHandle.java:286)
  However it's possible that other methods could be impacted.
  .
  

Local fix

• The problem can be avoided by disabling OSR for the affected
  method, e.g. for the case above this could be done using the JVM
  command line argument
  -Xjit:{java/lang/invoke/BruteArgumentMoverHandle.permuteArgument
  s(*}(disableOSR),dontInline={java/lang/invoke/BruteArgumentMover
  Handle.permuteArguments(*}
  Note that if there is an existing Xjit argument being used it
  will need to be merged with the above.
  

Problem summary

• The problem is caused when the compiler fails to account for a
  variable needing to be passed to the interpreter if OSR is used
  to transfer processing away from the jit'd method body.
  

Problem conclusion

• The compiler has been updated to ensure that variables that
  escape the method via OSR are correctly tracked and passed to
  the interpreter. The relevant changes are:
  https://github.com/eclipse-openj9/openj9/pull/14074
  https://github.com/eclipse-openj9/openj9/pull/18315
  .
  This APAR will be fixed in the following Releases:
  .
  IBM SDK, Java Technology Edition
     8    SR8 FP20  (8.0.8.20)
  .
  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