IBM Support

IT17129: Message outside of UOW discarded after asynchronous consuming client deregisters callback

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APAR status

  • Closed as program error.

Error description

  • This issue occurs in the following circumstances:
    
    A MQ client is consuming messages asynchronously from a
    destination and it invokes MQCB MQOP_DEREGISTER to deregister
    the callback function.
    A message arrives on the queue.
    The queue manager delivers the message to the MQ client but the
    MQ client does not have a registered callback function and so is
    unable to deliver the message to application.  As a result the
    message gets 'stuck' in the MQ Client memory.  If the message is
    being delivered outside of a unit of work then the message is
    discarded when the object handle is closed.
    

Local fix

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    This issue affects IBM MQ V8 and later customers who use the MQ
    client to consume messages asynchronously.  Note specifically
    that users of the IBM Integration Broker (IIB) V10 MQInput node
    may be affected by this issue if their MQInput node is
    configured to connect to a queue manager using MQ client
    bindings.
    
    
    Platforms affected:
    MultiPlatform
    
    ****************************************************************
    PROBLEM DESCRIPTION:
    This issue occurred if the following sequence of events took
    place :
    - A MQ client application was consuming messages asynchronously
    from a destination
    - The MQ client application invoked MQCB MQOP_DEREGISTER to
    deregister the callback function.
    - The consumption of messages was started for the connection
    (e.g. the client app calls MQCTL with the option MQOP_START).
    - A message arrived on the queue.
    
    In these circumstances then the queue manager may have delivered
    a message to the MQ client despite the fact that the MQ client
    does not have a registered callback function.  The MQ client was
    unable to deliver the message to the application, so the message
    was 'stuck' in the MQ client memory.  If the message was being
    delivered outside of a unit of work then the message was
    discarded when the object handle was closed.
    
    The problem was caused by a programming error which led to a
    mismatch in state between the MQ client and the MQ queue
    manager.
    

Problem conclusion

  • The queue manager code has been modified to ensure that the
    problem no longer occurs.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
    Version    Maintenance Level
    v7.5       7.5.0.8
    v8.0       8.0.0.6
    v9.0 CD    9.0.4
    v9.0 LTS   9.0.0.1
    
    The latest available maintenance can be obtained from
    'WebSphere MQ Recommended Fixes'
    http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
    
    If the maintenance level is not yet available information on
    its planned availability can be found in 'WebSphere MQ
    Planned Maintenance Release Dates'
    http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
    ---------------------------------------------------------------
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT17129

  • Reported component name

    WMQ BASE MULTIP

  • Reported component ID

    5724H7251

  • Reported release

    800

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2016-09-20

  • Closed date

    2016-10-28

  • Last modified date

    2017-06-01

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

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

Fix information

  • Fixed component name

    WMQ BASE MULTIP

  • Fixed component ID

    5724H7251

Applicable component levels

  • R800 PSY

       UP

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Document Information

Modified date:
01 June 2017