PI61683: WMQ JAVA THREADS FOR MQGET HANG AFTER WEBSPHERE MQ JMS MAINTENANCE IS APPLIED 16/05/04 PTF PECHANGE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Code introduced through PI46510/UI33362 can impact applications
  using an RRS enabled connection to WebSphere MQ ( including
  bindings mode connections from WAS ) When a connection to MQ is
  in an MQGET wait and either a message arrives or the wait
  interval expires, the code to post the waiting task can
  incorrectly determine that the task is no longer valid and skip
  the post call. This results in the connection remaining
  permanently suspended in the MQGET wait.
  .
  Additional keywords:
  WebSphere Application Server WAS WSAS
  IBM Integration Bus (formerly WebSphere Message Broker)
  

Local fix

• n/a
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 7 *
  *                 Release 1 Modification 0                     *
  ****************************************************************
  * PROBLEM DESCRIPTION: The following two problems are fixed by *
  *                      this APAR.                              *
  *                      1:                                      *
  *                      After applying UI16412, RRS             *
  *                      applications issuing MQGET with         *
  *                      MQGMO_WAIT hang if RRS is restarted     *
  *                      while the application is waiting to be  *
  *                      posted.                                 *
  *                                                              *
  *                      2:                                      *
  *                      After applying UI33362, RRS             *
  *                      applications (including IIB and WAS)    *
  *                      issuing MQGET calls can hang            *
  *                      indefinitely if the MQGET is issued on  *
  *                      a different TCB to that originally used *
  *                      by a context, and the original TCB is   *
  *                      no longer active                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  1:
  When RRS is restarted, any active RRS agents are driven through
  End of Task (EOT) processing. This should result in any such
  agents that are in an MQGET wait being posted when the handled
  is closed, however changes added to CSQM1P1W by PI08608 cause
  this post to be incorrectly skipped.
  
  2:
  When a getting application is being posted (for example, by the
  arrival of a suitable message, or the expiry of the get wait
  interval), code added to CSQM1P1W by PI46510 checks if the
  getter TCB is still active if there are any tasks in the getter
  address space in EOT processing.
  This check uses the tcbtoken stored in the getter's MTHR,
  however if the MQGET call was issued on a different TCB to the
  TCB the context originally used, the tcbtoken is incorrect and
  still relates to the original TCB. If that TCB has ended,
  CSQM1P1W incorrectly determines that the getter is going through
  EOT processing and skips posting the getter's ECB, leading to
  the reported problems.
  

Problem conclusion

• CSQMGET is changed to ensure the MTHR associated with an RRS
  MQGET request is updated with the correct tcbtoken for the TCB
  currently being used for the MQGET request, allowing the check
  in CSQM1P1W to correctly determine if that TCB is still active
  or not.
  CSQM1P1W is changed to no longer skip the post when an RRS
  agent is driven through EOT.
  100Y
  CSQMALL
  CSQMGET
  CSQM1P1W
  

Temporary fix

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

Comments

APAR Information

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

  PI61141

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

  UI37799

Modules/Macros

• CSQMALL  CSQMGET  CSQM1P1W
  

Fix information

• Fixed component name

  WMQ Z/OS V7

• Fixed component ID

  5655R3600

Applicable component levels

• R100 PSY UI37799

     UP16/05/26 P F605 «

Fix is available

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