IT24878: If a shared memory set is unavailable then the queue manager canenter an infinite loop

IBM MQ for HP NonStop Server V8.1 Fix Pack 8.1.0.7

APAR status

• Closed as program error.

Error description

• If a shared memory set is unavailable then the queue manager may
  enter an
  infinite loop when using CHLAUTH administration commands.  If
  this
  problem occurs then the IBM MQ amqzlaa0 process
  will be seen to use a large amount of CPU.
  
  Extract from a failure data capture (FDC) record that was
  generated as a result of the issue:
  
  WebSphere MQ First Failure Symptom Report
  =========================================
  Probe Id          :- XY388255
  Component         :- xcsConnectSharedMemSet
  Probe Description :- AMQ6109: An internal WebSphere MQ error has
  occurred.
  ----------------------------------------------------
  MQM Function Stack
  zlaMainThread
  zlaProcessMessage
  zlaProcessSPIRequest
  zlaSPIKernel
  zsqSPIKernel
  kpiGeneric
  kqiSetChlAuthMap
  rsxAccessCache
  xcsConnectSharedMemSet
  xcsFFST
  

Local fix

• Restarting the queue manager will work around the problem.  It
  may be necessary to end the queue manager with the -p
  (pre-emptive) option.
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users who remove IBM MQ shared memory resources may be affected
  by this issue.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  If a shared memory segment belonging to IBM MQ was removed when
  MQ is running then the amqzlaa0 process may have entered an
  infinite loop as it attempts to access this segment.
  

Problem conclusion

• The IBM MQ code was modified so that it does not continually
  attempt to access the shared memory resource if it does not
  exist.  Instead, an FDC record with probe RM951010 is generated
  and the following error will be seen when using CHLAUTH
  administration commands:
  
  SET CHLAUTH('*') TYPE(BLOCKADDR) ADDRLIST('xxx.xxx.xxx.xxx')
       1 : SET CHLAUTH('*') TYPE(BLOCKADDR)
  ADDRLIST('xxx.xxx.xxx.xxx')
  AMQ9774: Error accessing the Channel authentication table
  
  The queue manager should be restarted as soon as possible.  It
  is advisable to check whether the ipcrm (or host OS equivalent)
  command had recently been run by an administrator or a script,
  as MQ IPC resources should not be removed while the queue
  manager is running.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v7.5       7.5.0.9
  v8.0       8.0.0.11
  v9.0 LTS   9.0.0.6
  v9.1 CD    9.1.1
  v9.1 LTS   9.1.0.1
  
  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

  WEBSPHERE MQ 7.

• Fixed component ID

  5724H7240

Applicable component levels

• R750 PSY

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