PI50784: WMQ: SHUTDOWN HANG OCCURS WHEN A STOP TRACE IS ISSUED FOLLOWING A PREVIOUS START TRACE COMMAND

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• As soon as the customer did the following steps, the queue
  manager hung during shutdown:
  .
  1). Brought QMGR CSQ1 up.
  2). Issued: +CSQ1 START TRACE(ACCTG) DEST(SMF) CLASS(*) RMID(*)
  3). Issued: +CSQ1 DISPLAY TRACE(*)
  4). Ran the batchjob that put the 250K messages on the queue.
  5). Ran the batchjob that read the 250K messages from the
      queue.
  6). Issued: +CSQ1 STOP TRACE(ACCTG) DEST(SMF) CLASS(*) RMID(*)
  7). Issued: +CSQ1 DISPLAY TRACE(*)
  8). Issued: +CSQ1 STOP QMGR
  The change team have been investigating this further and I can
  now see that the shutdown hang that the customer saw was
  actually due to a different problem to that described by
  PI36959. In the customer's case the shutdown hang occurs when a
  STOP TRACE is issued following a previous START TRACE command
  (CSQWVCST obtains an IASY buffer and sets it to xFF during
  START TRACE processing. The IASY buffer gets released during
  the STOP TRACE processing, and may be used for shutdown
  checkpoint processing - however, the residual xFF's cause the
  problem seen here). The Change Team has recreated this shutdown
  on their test system.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 8 *
  *                 Release 0 Modification 0                     *
  ****************************************************************
  * PROBLEM DESCRIPTION: After the commands                      *
  *                                                              *
  *                      START TRACE(ACCTG) CLASS(*) DEST(SMF)   *
  *                      and                                     *
  *                      STOP TRACE(ACCTG) CLASS(*) DEST(SMF)    *
  *                                                              *
  *                      have been issued the queue manager may  *
  *                      hang during termination.                *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  When a START TRACE(ACCTG) CLASS(*) DEST(SMF)
  command is issued an IASY buffer is populated with some x'FF's
  and later when the trace is stopped the buffer is released.
  However during queue manager termination CSQWVSBH uses this
  storage for an IAMQ to queue to CSQWVSMT to force statistics
  to be written. However because the IAMQFNWU flag is set on,
  residually, the CSQWVSMT task is not resumed and queue
  manager termination hangs indefinitely.
  

Problem conclusion

• CSQWVSBH has been changed to correctly initialise the IAMQ
  allowing the queue manager to terminate normally.
  000Y
  CSQWVSBH
  

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:

  UI34855

Modules/Macros

• CSQWVSBH
  

Fix information

• Fixed component name

  WMQ Z/OS 8

• Fixed component ID

  5655W9700

Applicable component levels

• R000 PSY UI34855

     UP16/03/03 P F603

Fix is available

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