PI56638: WMQ 800 TOPIC'S DESTINATION QUEUE WHICH HAS USEDLQ(NO), CAN CAUSE PUBLICATION PROCESSING NOT RELEASING MUTEX. QMGR HANGS.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• WMQ 800 Subscriber to a TOPIC which has a destination queue
  defined with USEDLQ(NO) can cause publication processing to
  not release a mutex, which causes the queue manager to hang.
  .
  Additional Symptoms:
  The MQ Command Server is not responding despite showing a
  running status:
    - CSQOREXX panels are hung
    - CSQUTIL batch jobs will not execute
    - STOP CMDSERV results in
        CSQN017I COMMAND SERVER STATUS IS STOPPING
      but the Command Server does not end
    - The curdepth on the SYSTEM.COMMAND.INPUT.QUEUE goes up and
      down, but it can not be completely cleared
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 8 *
  *                 Release 0 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: After a failure to publish a message to *
  *                      a subscriber, a hang occurs in tasks    *
  *                      attempting to alter or delete the       *
  *                      subscriber, until the publishing job    *
  *                      ends.                                   *
  *                      If DELETE SUB is used to delete the     *
  *                      subscription, the command server hangs, *
  *                      leading to the queue manager failing    *
  *                      to process any further commands.        *
  *                                                              *
  *                      Other symptoms can include publisher    *
  *                       tasks looping with high cpu            *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  A publishing task located a matching subscriber and obtained a
  read mutex on the subscriber control block. When delivering a
  copy of the message to the subscriber, the message could not be
  delivered to the subscriber's queue, and was not delivered to
  the dead letter queue (either because the topic uses USEDLQ(NO),
  or the attempt to put the message to the dead letter queue
  failed). If the message delivery options (NPMSGDLV/PMSGDLV)
  indicate that the failed delivery should cause the publish
  operation to fail, CSQMTPUT returns MQRC_PUBLICATION_FAILURE
  (MQRC 2502), however it does not release the mutex on the
  subscriber.
  Any task requiring a write mutex on the same subscriber
  (for example, the command processor when processing a DELETE SUB
  or ALTER SUB command, or the topic expiry task) will hang
  waiting for the read mutex to be released, however this will
  not occur until the publishing job (for example, the channel
  initiator) ends.
  

Problem conclusion

• CSQMTPUT is changed to ensure the read mutex on the subscriber
  is always released before returning.
  000Y
  CSQMTPUT
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  PI59297 UI36599

Modules/Macros

• CSQMTPUT
  

Fix information

• Fixed component name

  WMQ Z/OS 8

• Fixed component ID

  5655W9700

Applicable component levels

• R000 PSY UI36599

     UP16/05/04 P F605 ¢

Fix is available

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