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IZ85974: IN WMQ V7.0 FASTTRANSFERORDER PARAMETER IS NOT WORKING AS EXPECTED WHEN ASYNCHRONOUS CONSUME IS BEING USED.

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APAR status

  • Closed as program error.

Error description

  • The FastTransferOrder tuning parameter allows the queue manager
    to deliver messages in a more round-robin manner by servicing
    waiting MQGETs in FIFO order rather than the default LIFO order.
    
    In WebSphere MQ v7.0 the FastTransferOrder tuning parameter is
    not working as expected when asynchronous consume is being used
    to deliver messages to consumers.  Message delivery is seen to
    favour a subset of consumers rather than delivery being balanced
    across all consumers.
    

Local fix

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    Users who use WebSphere MQ clients with SHARECNV on the channel
    set to a value greater than 0, or are using the asynchronous
    consume facility of WebSphere MQ v7.0 to enable multiple
    consumers to retrieve messages from a queue.
    
    Users of:
    
    - WebSphere Application Server V7
    - WebSphere Application Server V6 who have configured the
    application server to use the WebSphere MQ V7 classes for JMS
    (by setting the MQ_INSTALL_ROOT variable to point to the
    directory where WebSphere MQ V7 has been installed)
    
    that connect to a WebSphere MQ V7 queue manager using WebSphere
    MQ messaging provider normal mode will also be affected, as the
    application server will use the asynchronous consume facility
    of WebSphere MQ V7 when receiving messages.
    
    Platforms affected:
     All Distributed (iSeries, all Unix and Windows)
    ****************************************************************
    PROBLEM SUMMARY:
    Waiting MQGETs are not removed from the list of waiters when
    they are consuming messages asynchronously and so messages are
    constantly delivered only to the oldest consumers in preference
    to those who have most recently joined the list of waiting
    MQGETs.
    

Problem conclusion

  • The code has been changed so that if the FastTransferOrder
    tuning parameter is in use and the waiter is using asynchronous
    consume then the waiter is moved to the end of the waiter list
    after it has been chosen for message delivery.  The effect of
    this change is that messages are more evenly distributed amongst
    consumers.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
                       v7.0
    Platform           Fix Pack 7.0.1.5
    --------           --------------------
    Windows            U200324
    AIX                U839183
    HP-UX (PA-RISC)    U839621
    HP-UX (Itanium)    U839626
    Solaris (SPARC)    U839622
    Solaris (x86-64)   U839628
    iSeries            tbc_p700_0_1_5
    Linux (x86)        U839623
    Linux (x86-64)     U839627
    Linux (zSeries)    U839624
    Linux (Power)      U839625
    
    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

    IZ85974

  • Reported component name

    WMQ LIN X86 V7

  • Reported component ID

    5724H7224

  • Reported release

    701

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2010-09-29

  • Closed date

    2010-11-30

  • Last modified date

    2011-03-01

  • 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 LIN X86 V7

  • Fixed component ID

    5724H7224

Applicable component levels

  • R701 PSY

       UP



Document information

More support for: WebSphere MQ
APAR / Maintenance

Software version: 7.0.1

Reference #: IZ85974

Modified date: 01 March 2011