IZ96848: JAVA6 JIT - EXECUTING THE WRONG CODE WHEN TWO IMPLEMENTATIONS EX IST

PM52687: SHIP SDK APAR IV06580 and defect 184227 as WSAS IFIX
PM53783: SHIP several SDK apars as WSAS iFix on top of 1.6 SR9 FP2

APAR status

• Closed as program error.

Error description

• Error Message: Executing the wrong implementation of an abstract
  method.
  Possible symptoms are varied:
  1) Crash in JIT compiled code or the interpreter
  2) In correct behaviour of a Java application
  3) Unexpected exception
  4) Crash in JIT runtime routines
  5) Crash in GC
  .
  Stack Trace: N/A
  .
  The problem only exist in Java6 and requires that a class is
  loaded during JIT compilation of a method where an assumption
  was made based on the fact that only one implementation of an
  abstract method exists. The new class that was loaded contains a
  2nd implementation of that method invalidating the assumption
  before the JIT compilation was completed.
  

Local fix

• The problem can be avoided by using the following Java command
  line option:
  -Xjit:disableInnerPreexistence,disableInvariantArgumentPreexiste
  nce,disableRedundantMonitorElimination
  

Problem summary

• When a class is loaded that invalidates a compile time
  assumption before the compilation has completed, the JIT will
  abort the compilation leaving a inconsistent state in some class
  metadata that may cause future JIT compilations to make invalid
  assumptions about the class hierarchy.
  

Problem conclusion

• This defect will be fixed in:
  6.0.0 SR9 FP3
  6.0.1 GA FP1
  .
  The JIT was modified so that aborted compilations will do proper
  class metadata maintenance before exiting the compiler.
  .
  To obtain the fix:
  Install build 20110323 or later
  

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:

  PM54794

Fix information

• Fixed component name

  JIT

• Fixed component ID

  620700124

Applicable component levels

• R600 PSY

     UP