IJ25978: INTERMITTENT ASSERTION FAILURE REPORTED

APAR status

• Closed as program error.

Error description

• Error Message: ASSERTION FAILED ** at
  ../../../../gc_glue_java/ScavengerRootScanner.hpp:108:
  ((MM_StackSlotValidator(MM_StackSlotValidator::NOT_ON_HEAP,
  *slotPtr, stackLocation, walkState).validate(_env)))
  .
  Stack Trace: In a javacore file produced, information similar to
  the following might be found:
  3XEHSTTYPE 21:54:46:573159000 GMT j9mm.479 - * ** ASSERTION
  FAILED ** at
  ../../../../gc_glue_java/ScavengerRootScanner.hpp:108:
  ((MM_StackSlotValidator(MM_StackSlotValidator::NOT_ON_HEAP,
  *slotPtr, stackLocation, walkState).validate(_env)))
  3XEHSTTYPE 21:54:46:573156000 GMT j9mm.491 -
  *<StackSlotValidator::reportStackSlot
  3XEHSTTYPE 21:54:46:573154000 GMT j9mm.493 - *
  stack=AEBF5550-AEBFB168
  3XEHSTTYPE 21:54:46:573145000 GMT j9mm.490 - *
  method=B3ACE300 (MyJavaClass.myMethod(LArgumentType;)V)
  (Interpreted)
  3XEHSTTYPE 21:54:46:573135000 GMT j9mm.489 - *
  jitInfo=00000000
  3XEHSTTYPE 21:54:46:573128000 GMT j9mm.488 - *
  literals=B3ACE300
  3XEHSTTYPE 21:54:46:573122000 GMT j9mm.487 - *
  walkSP=AEBFAF50
  3XEHSTTYPE 21:54:46:573115000 GMT j9mm.486 - *
  arg0EA=AEBFAF74
  3XEHSTTYPE 21:54:46:573108000 GMT j9mm.485 - *
  framesWalked=1
  3XEHSTTYPE 21:54:46:573101000 GMT j9mm.484 - * PC=B39210D0
  3XEHSTTYPE 21:54:46:573094000 GMT j9mm.483 - * O-Slot
  value=B40E3094
  3XEHSTTYPE 21:54:46:573087000 GMT j9mm.482 - *
  O-Slot=AEBFAF5C
  3XEHSTTYPE 21:54:46:573076000 GMT j9mm.481 - * Object
  neither in heap nor stack-allocated in thread Pooled Thread #10
  .
  

Local fix

• The failure can be worked around by specifying the
  -Xjit:disableEscapeAnalysis option. Note that specifying this
  option might have an effect on program performance
  

Problem summary

• The Escape Analysis (EA) optimizer of the Java JIT compiler
  attempts to allocate some Java objects on the stack for a method
  invocation rather than the heap if the use of those objects is
  entirely contained within that method invocation. This is done
  in order to improve performance by reducing the amount of object
  allocation on the heap.
  If an object might still be used outside the method invocation -
  which is referred to as "escaping" - but relatively
  infrequently, EA might still allocate the object on the stack.
  It will generate code that will copy the object into an object
  allocated on the heap at the point at which the escape occurs.
  One example of such escaping can occur if a method that has been
  JIT compiled has to transfer execution of that method to the JVM
  interpreter while the method is executing. Any objects that
  were allocated on the stack by EA that need to be accessible to
  the interpreter in order for it to continue executing the method
  must be copied to heap allocated objects at the point of the
  transfer of execution to the interpreter.
  In the case that triggers the assertion failure, an object that
  had been allocated on the stack by EA was not copied to a heap
  allocated object at the point of transition to the interpreter.
  The JVM Garbage Collector did not recognize the address of that
  object as being on the heap nor being a still valid address on
  the stack, and it reported the assertion failure.
  

Problem conclusion

• The problem was fixed by ensuring the Escape Analysis optimizer
  correctly identifies cases in which a stack allocated object
  needs to be copied to a heap allocated object at the point at
  which the invocation of a Java JIT compiled method needs to
  transfer its execution to the JVM interpreter.
  .
  This APAR will be fixed in the following Java Releases:
   8 SR6 FP15 (8.0.6.15)
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, information about the available
  Service Refreshes and Fix Packs can be found at:
   https://www.ibm.com/developerworks/java/jdk/
  

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