IV25686: TRACEASSERT IN PARALLELSCAVENGER AT LINE 2616

APAR status

• Closed as program error.

Error description

• Error Message: j9mm.107    *   ** ASSERTION FAILED ** at
  ParallelScavenger.cpp:2616:
  ((env->_referenceObjectBuffer.isEmpty()))
  JVMDUMP039I Processing dump event "traceassert"
  .
  Stack Trace: Native Stack:
  j9dump_create() from
  /sdk/jre/lib/amd64/compressedrefs/libj9prt26.so
  doSystemDump() from
  /sdk/jre/lib/amd64/compressedrefs/libj9dmp26.so
  j9sig_protect() from
  /sdk/jre/lib/amd64/compressedrefs/libj9prt26.so
  runDumpFunction() from
  /sdk/jre/lib/amd64/compressedrefs/libj9dmp26.so
  runDumpAgent() from
  /sdk/jre/lib/amd64/compressedrefs/libj9dmp26.so
  triggerDumpAgents() from
  /sdk/jre/lib/amd64/compressedrefs/libj9dmp26.so
  twAssertion() from
  /sdk/jre/lib/amd64/compressedrefs/libj9trc26.so
  utsTraceV() from
  /sdk/jre/lib/amd64/compressedrefs/libj9ute26.so
  j9Trace() from  /sdk/jre/lib/amd64/compressedrefs/libj9trc26.so
  
  MM_ParallelScavenger::workThreadGarbageCollect(MM_EnvironmentSta
  ndard*)() from /sdk/jre/lib/amd64/compressedrefs/libj9gc26.so
  MM_ParallelDispatcher::slaveEntryPoint(MM_EnvironmentModron*)()
  from /sdk/jre/lib/amd64/compressedrefs/libj9gc26.so
  dispatcher_thread_proc2(J9PortLibrary*, void*)()  from
  /sdk/jre/lib/amd64/compressedrefs/libj9gc26.so
  j9sig_protect() from
  /sdk/jre/lib/amd64/compressedrefs/libj9prt26.so
  dispatcher_thread_proc() from
  /sdk/jre/lib/amd64/compressedrefs/libj9gc26.so
  thread_wrapper() from
  /sdk/jre/lib/amd64/compressedrefs/libj9thr26.so
  start_thread() from ./lib64/libpthread.so.0
  clone() from ./lib64/libc.so.6
  .
  The assertion failure occurs due to a scavenge abort.
  When the GC fails to either "copy" or "tenure" an object, it
  aborts the current scavenge cycle.
  After abort, we are checking for a GC reference queue structure
  is empty , but is not because the scavenge phase can resurrected
  objects during finalization processing.
  You will know if you are hitting the traceassert due to scavenge
  abort from the following two points
  (1) ASSERTION FAILED at ParallelScavenger.cpp:2616 , and the JDK
  is Java6.0.1 SR1 fp1
  (2) you see the GC history of the javacore section containing
  mostly the following trace point:
  3STHSTTYPE     22:48:07:273883000 GMT j9mm.63 -   Set scavenger
  backout flag=true
  

Local fix

• Change of GC policy from "gencon" to "optthruput"
  

Problem summary

• A "traceassert" is raised during Parallel Scavenge phase. This
  is caused with the scavenge phase aborts, and one of the GC
  reference queue structure is unconditionally checked for
  emptiness - when chances are it may not be.
  

Problem conclusion

• This defect will be fixed in:
  6.0.1 SR4
  7.0.0 SR3
  .
  The JVM GC code has been updated to conditionally check for the
  GC reference queue structure.
  

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

  J9 COMMON CODE

• Fixed component ID

  620700127

Applicable component levels

• R260 PSY

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