PM82570: IMS WILL HANG WAITING FOR A CQSMOVE REQUEST TO COMPLETE WHEN THE STRUCTURE IS IN OVERFLOW WITH NO OVERFLOW STRUCTURE.

A fix is available

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APAR status

  • Closed as program error.

Error description

  • IMS can hang waiting for a CQSMOVE request to complete under
    the following circumstances:
    1. MSGQ structure is in overflow processing and there is no
       overflow structure.
    2. CQSMOVE is issued to move from one queue name to another.
       (i.e. Dequeuing the suspend queue)
    3. The source queue name must have been selected for overflow.
    4. The destination queue name must not have been selected for
        overflow.
     Due to a problem in CQSMOV00 when completing the move logic,
    there was no response to IMS for this request. Since this
    flow would have an indication that there was an active queue
    manager flow in the system, IMS will hang at the time the
    next checkpoint is issued.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All V11 IMS users of shared queues and CQS.  *
    ****************************************************************
    * PROBLEM DESCRIPTION: IMS waits for CQS to complete a move    *
    *                      request and appears hung during a       *
    *                      simple checkpoint.                      *
    ****************************************************************
    * RECOMMENDATION: INSTALL CORRECTIVE SERVICE FOR APAR/PTF      *
    ****************************************************************
    The queue structure is in the overflow mode and no overflow
    structure is defined.  IMS requests CQS to move messages between
    client queues, such as dequeueing the suspend queue.  CQS
    attempts to move messages from a source queue which has been
    selected for overflow to a destination queue which has not been
    selected for overflow.
    
    During the move request processing, CQS incorrectly thinks that
    the source queue is quiesced and decides to stop the move
    request and not to return a response to IMS.  If the queue was
    quiesced because of the overflow condition, then the move
    process would stop and resume processing the request when the
    overflow condition ends.  Here the source queue is actually not
    quiesced, thus CQS should continue completing the IMS's move
    request.  The CQS's move request processing stoppage impacts the
    IMS checkpoint process.
    
    IMS keeps track of the QPOOL count of in-progress operations to
    determine when to process a checkpoint.  If the count is zero
    indicating there is no tasks in progress, then the checkpoint
    will proceed.  If the count is not zero indicating there are
    some tasks in progress, then the checkpoint waits until the
    count becomes zero or no tasks are running.  Since the CQS move
    request task never completes, the count never goes down to zero,
    the checkpoint goes into the wait state, this holds up all other
    tasks waiting behind the checkpoint, and IMS hangs.
    
    This hang condition happens when a combination of the following
    is true:
    
     . The queue structure must be an overflow mode with no overflow
       structure.
     . CQSMOVE is issued to move messages between client queues.
     . The source queue name must have been selected for overflow.
     . The destination queue name must not have been selected for
       overflow.
    

Problem conclusion

  • GEN:
    KEYWORDS:
     SYSPLEXDS
    
    *** END IMS KEYWORDS ***
    
    CQSMOV00 - CQSMOVE request processor.
    In the move-by-queue-name routine OLDQ0000, changed to ensure
    that when the source queue is not quiesced, the move process
    should continue to completion.
    

Temporary fix

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

Comments

APAR Information

  • APAR number

    PM82570

  • Reported component name

    IMS V11

  • Reported component ID

    5635A0200

  • Reported release

    101

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-02-11

  • Closed date

    2013-02-21

  • Last modified date

    2013-04-02

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

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

    PM82626 PM82627 UK91994

Modules/Macros

  • CQSMOV00
    

Fix information

  • Fixed component name

    IMS V11

  • Fixed component ID

    5635A0200

Applicable component levels

  • R100 PSY UK91994

       UP13/03/05 P F303 ½

Fix is available

  • Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.



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Document information


More support for:

IMS

Software version:

101

Reference #:

PM82570

Modified date:

2013-04-02

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