IT29222: Null pointer memory exception reported on Windows when trace is on and thread is ending

APAR status

• Closed as program error.

Error description

• Memory exceptions are reported and Failure Data Capture (FDC)
  records will be generated with the following call stacks:
  
  Stack 1 - most recent call at the top
  xruRecordThreadUsage
  xtrEstablishTraceStatus
  xtr_FNC_entry
  xtrAnyThreadsTracing
  xtrTurnOffTrace
  xcsDestroyThread
  ThreadMain
  
  Stack 2 - most recent call at the top
  GenerateFFST
  xehExceptionHandler
  ThreadMain
  

Local fix

• N/A
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users of IBM MQ on Windows who switch on MQ trace at the MQ
  9.1.0.2 level.
  
  
  Platforms affected:
  Windows
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  While uninitializing MQ data on a thread that was about to end,
  the MQ code freed some memory and set some pointers to null.
  Then when MQ entered a subroutine that ends the trace for that
  thread the null pointer was referenced and MQ suffered the
  memory exceptions described.
  
  This issue was caused by the code change for APAR IT28639 which
  was included in the 9.1.0.2 fix pack.
  

Problem conclusion

• The logic in the MQ trace code was wrong.  It has been corrected
  such that the pointer is not set to null.  The subroutine
  mentioned therefore does not suffer the memory exception.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.1 CD    9.1.3
  v9.1 LTS   9.1.0.3
  
  The latest available maintenance can be obtained from
  'WebSphere MQ Recommended Fixes'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
  
  If the maintenance level is not yet available information on
  its planned availability can be found in 'WebSphere MQ
  Planned Maintenance Release Dates'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
  ---------------------------------------------------------------
  

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

  IBM MQ BASE MP

• Fixed component ID

  5724H7271

Applicable component levels