IJ47675: JAVA JIT: DIVIDE BY ZERO IN COMPUTETHREADCPUUTILOVERLASTNNS()

APAR status

• Closed as program error.

Error description

• Error Message: A 0C9/FPE (integer Divide by zero) OS signal is
  thrown causing the JVM to abort.
  .
  Stack Trace:
  {libj9jit29.so}{CpuSelfThreadUtilization::computeThreadCpuUtilOv
  erLastNns(long)}
  {libj9jit29.so}{DoCalculateOverallCompCPUUtilization(...)}
  {libj9jit29.so}{samplerThreadProc(void*)}
  {libj9thr29.so}{thread_wrapper}
  .
  The problem can occur on X86 and IBM-Z machines (but not on
  POWER because an integer divide by zero does not cause a signal
  on POWER). On X86 it would be a SIGFPE and on IBM-Z (zOS) it
  would be a 0C9.
  

Local fix

• The issue is typically made possible by enabling JIT verbose
  options "compilationThreads" or "compilationThreadsDetails" or
  by requesting trace point "j9jit.42". The issue could be avoided
  by making sure those are not enabled.
  i.e. Remove the java command line argument
  "-Xjit:verbose={compilationThreads}"
  or
  "-Xjit:verbose={compilationThreadsDetails}
  

Problem summary

• The JIT can update it's CPU utilization data structure in more
  then one thread which results in a race condition which could
  lead to a divide by zero in computeThreadCpuUtilOverLastNns().
  

Problem conclusion

• The JIT was modified so that it checks for a 0 divisor in the
  computeThreadCpuUtilOverLastNns() method and returns an error
  (-1) to the caller in such cases.
  .
  This APAR will be fixed in the following Releases:
  .
  IBM SDK, Java Technology Edition
     8    SR8 FP11  (8.0.8.11)
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, information about the available
  maintenance can be found at:
             https://www.ibm.com/support/pages/java-sdk
  

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