IV69571: FDC WITH PROBEID KN346080 WHEN USING ASYNCHRONOUS CONSUME FUNCTIONALITY

APAR status

• Closed as program error.

Error description

• When using the asynchronous consume functionality of WebSphere
  MQ, an FDC with probe identifier KN346080 is produced with the
  following call stack:
  
  MQM Function Stack
  zlsMainThread
  zlsProcessMessage
  zlsProcessMQIRequest
  zlsMQGETM
  zsqMQGETM
  kpiMQGETM
  xcsFFST
  
  The FDC may also contain a trace sequence which looks like this:
  
  -----{ kqiWaitForABit
  ------{ xcsWaitEventSem
  -------{ xlsWaitEvent
  Data: 0x00000064 0x80000000
  -------} xlsWaitEvent rc=OK
  ------} xcsWaitEventSem rc=OK
  ------{ xcsResetEventSem
  -------{ xlsResetEvent
  -------} xlsResetEvent rc=OK
  ------} xcsResetEventSem rc=OK
  -----} kqiWaitForABit rc=Unknown(5)
  
  Subsequent FDCs with a probe identifier of XC014030 and this
  call stack may also be seen:
  
   Comment1 :- Detected Corrupted Quickcell
   Comment2 :- 100886
  
  +---------------------------------------------------------------
  --------------+
  
  MQM Function Stack
  zlsMainThread
  zlsProcessMessage
  zlsProcessMQIRequest
  zlsMQCB
  zsqMQCB
  kpiMQCB
  kqiRegisterConsumer
  kqiAllocateWaiter
  xcsAllocateQuickCell
  xcsFFST
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users of the IBM MQ asynchronous consume functionality may be
  affected by this problem
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  A flaw in the order of code meant that a waiting asynchronous
  MQGET may have been incorrectly made available to consume a
  message. This could lead to the consumer being posted to wake up
  when it should not have been.
  
  Being woken incorrectly led to the asynchronous consumer trying
  to access a piece of memory that had been freed.
  

Problem conclusion

• The code was modified so that the asynchronous consumer would
  not be eligible to consume a message unless it was really able
  to do so.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v7.1       7.1.0.7
  v7.5       7.5.0.6
  v8.0       8.0.0.3
  
  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

  WMQ LIN X86 V7

• Fixed component ID

  5724H7224

Applicable component levels