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IC66603: TOPIC LISTENERS RECEIVING SAME MESSAGE TWICE AFTER QUEUE MANAGER FAILOVER WHEN USING MQ V7 IN JBOSS

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APAR status

  • Closed as program error.

Error description

  • Two instances of the same message are seen by an application
    running in JBoss when using the WebSphere MQ v7 Resource Adapter
    (RA).  The duplicate messages are seen shortly after the queue
    manager fails over.
    
    The issue is seen when using two applications running in
    separate instances of an application server.  One sends a
    message which the other picks up using a topic listener.
    Shortly after the queue manager in use has failed over to
    another queue manager running on a different server the
    receiving application receives a duplicate message.  That is, it
    sees the same message twice.
    
    After a restart of the partition with the sending application,
    no further duplicate messages are seen.
    

Local fix

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    This issue affect users of the WebSphere MQ v7 Resource Adapter
    connecting to a queue manager who restart their queue manager
    twice as part of a failover, or otherwise break a connection as
    it is being rebuilt.
    
    Platforms affected:
    All Distributed (iSeries, all Unix and Windows) +Java
    ****************************************************************
    PROBLEM SUMMARY:
    When a connection from the resource adapter to the queue manager
    was broken, the resource adapter created a reconnection helper
    thread to rebuild this connection and its associated consumer.
    
    If this new connection was broken after the connection was
    created but before the consumer was created, a new reconnection
    helper thread was created to reconnect what the resource adapter
    thought was a new broken connection.
    
    However, as the original reconnection helper thread treated this
    break in the connection as a failure to rebuild the connection,
    it would continue in its attempt to reconnect.
    
    This meant we could end up with two reconnection helper threads
    active for a connection, and so when they were both eventually
    successful in reconnecting, we would have two instances of a
    consumer, where before the break in the connection there was
    only one.
    

Problem conclusion

  • A broken connection when recreating a consumer now does not
    create a new reconnection helper thread, instead the original
    thread handles the reconnection. Only one reconnection helper
    thread can now be active for a consumer at a time.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
                       v7.0
    Platform           Fix Pack 7.0.1.3
    --------           --------------------
    Windows            U200320
    AIX                U834987
    HP-UX (PA-RISC)    U834414
    HP-UX (Itanium)    U834413
    Solaris (SPARC)    U834986
    Solaris (x86-64)   U834210
    iSeries            tbc_p700_0_1_3
    Linux (x86)        U834415
    Linux (x86-64)     U834985
    Linux (zSeries)    U834412
    Linux (Power)      U835662
    
    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

    IC66603

  • Reported component name

    WMQ WINDOWS V7

  • Reported component ID

    5724H7220

  • Reported release

    700

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2010-02-23

  • Closed date

    2010-04-28

  • Last modified date

    2010-04-28

  • 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 WINDOWS V7

  • Fixed component ID

    5724H7220

Applicable component levels

  • R700 PSY

       UP

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Document Information

Modified date:
28 April 2010