IV58762: JAVA PROCESS HANGS DURING GARBAGE COLLECTION WHEN A JIT-COMPILED METHOD HAS A VERY LARGE STACK FRAME

APAR status

• Closed as program error.

Error description

• Error Message: The JVM garbage collector hangs while walking
  the stack frame of a possibly very large JIT-compiled method.
  .
  Stack Trace:
  walkJITFrameSlots()
  jitWalkFrame()
  jitWalkStackFrames()
  walkStackFrames()
  GC_VMThreadStackSlotIterator::scanSlots()
  MM_RootScanner::scanOneThread()
  MM_RootScanner::scanThreads()
  MM_RootScanner::scanRoots()
  MM_ParallelScavenger::scavengeRoots()
  MM_ParallelScavenger::workThreadGarbageCollect()
  MM_ParallelScavengeTask::run()
  .
  

Local fix

• The problem can be avoided if the JIT-compiled method owning
  the stack frame can be identified. The method can be excluded
  from compilation with -Xjit:exclude={*method_name*}, to prevent
  the GC from hanging.
  

Problem summary

• The problem occurs when the JIT generates code for a method that
  requires a stack frame size that is larger than 32KB. This
  results in a field overflow when calculating a stack offset in
  the meta-data used by the stack walker. The overflow results in
  a near infinite loop in the walkJITFrameSlots() function.
  

Problem conclusion

• The JIT has been modified so that it will abort any compilation
  that would result in a stack frame size that is larger than
  32KB.
  .
  This APAR will be fixed in the following Java Releases:
     6    SR16 FP2  (6.0.16.2)
     6 R1 SR8 FP2   (6.1.8.2)
     7    SR8       (7.0.8.0)
     7 R1 SR2       (7.1.2.0)
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, Java maintenance is available
  from:
             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

• R600 PSY

     UP

• R260 PSY

     UP

• R130 PSY

     UP