PI87162: WMQ Z/OS V9.0.3:MQ MSTR AND CHINIT HANG AT START UP DUE TO CONTENTION FOR THE SYSZTIOT ENQ

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Customer complained that the chinit failed to initialize when
  offload failed due to unmounted tape. Once the outstanding tape
  mount was issued the CHINIT address completed initialization .
  In chin joblog:
  The CHIN joblog tells the CHINIT initialization started
  at 15:18:38 and over 8 mins the initialization completed as
  below:
  15.18.38 S0088623 CSQX001I !MQZ2 CSQXJST Channel initiator
  starting
  15.27.09 S0088623 +CSQX022I !MQZ2 CSQXSUPR Channel initiator
  initialization complete
  
  The delay is caused due to contention for the SYSZTIOT ENQ for
  the queue  manager address space.
  The offload task has acquired this ENQ, presumably while doing
  DYNALLOC for the archive dataset, however it is suspended
  waiting on an ENQ held  by DFHSM.
  While this is taking place, the pubsub component of the queue
  manager is   started, and attempts to open the datasets in the
  CSQINPT DD, however as  this operation also requires the
  SYSZTIOT ENQ, which is still held by offload processing, it is
  suspended.
  The chinit is also starting up, and because it is clustered, it
  has to wait for the queue manager pubsub component to start, so
  that it is able to process any cluster topic definitions - as
  pubsub startup is delayed,   this results in the chinit startup
  also being delayed.
  Unfortunately contention for the SYSZTIOT has the potential to
  delay  queue manager startup processing, however in the past we
  have been able to avoid some of the causes of such contention.
  
  
  
  
  Additional Symptom(s) Search Keyword(s):
  

Local fix

• n/a
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
  *                 Release 1 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: Channel initiator hangs during startup  *
  *                      due to SYSZTIOT contention.             *
  ****************************************************************
  While starting the queue manager detected an outstanding log
  offload, and issued SVC99 (DYNALLOC) to allocate an archive
  log dataset.
  Due to unavailable tape resources, the SVC call was delayed
  while holding the SYSZTIOT ENQ for the queue manager address
  space.
  When Topic Manager attempted to process the CSQINPT DD, it
  required this ENQ, and was suspended until it is available. This
  caused a delay in publish/subscribe initialisation.
  During chinit startup, the repository task detected there were
  clustered topics defined and suspended waiting for pubsub
  initialisation to complete.
  

Problem conclusion

• CSQNINS and CSQNINPT are changed to open the CSQINPT/CSQOUTT
  DD prior to the point where log offloading is started,
  preventing any SYSZTIOT contention affecting the log offload
  from also delaying pubsub and channel initiator startup.
  

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:

  UI63994

Modules/Macros

• CSQNINPT CSQNINS
  

Fix information

• Fixed component name

  MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R100 PSY UI63994

     UP19/07/23 P F907 ¢

Fix is available

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