IBM Support

IY97558: Agent process does not return from a MQGET call for a period of time significantly larger than the time-out specified

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APAR status

  • Closed as program error.

Error description

  • In an agent with multiple applications servicing an individual
    queue, one particular application ends up in an MQGET call for
    an extended period of time when MQGMO_WAIT is specified. This
    results in the application seemingly hanging until the MQGET
    call returns.
    

Local fix

  • Not Applicable
    

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    Anyone using MQ with multiple applications doing MQGET with
    MQGMO_WAIT specified on a queue.
    
    Platforms affected:
     All Distributed (iSeries, all Unix and Windows)
    ****************************************************************
    PROBLEM SUMMARY:
    The problem was caused by multiple agent threads competing for
    messages on a queue. A particular thread was consistently
    failing to retrieve a message from the queue prior to other
    threads obtaining the message. However, the timer used for the
    get with wait call was always being reset to 0 every time the
    thread was notified that a new message was ready for retrieval.
    As such, it was caught in an endless loop until it either
    successfully retrieved a message from the queue prior to other
    threads waiting, or a suitable amount of time longer than the
    wait interval passed without any new messages appearing on the
    queue.
    

Problem conclusion

  • The solution was to avoid resetting the timer after each failed
    attempt to retrieve a message. As such, the wait interval was
    now able to expire and the MQGET could then return.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
                       v6.0
    Platform           Fix Pack 6.0.2.3
    --------           --------------------
    Windows            U200279
    AIX                U811346
    HP-UX (PA-RISC)    U811630
    HP-UX (Itanium)    U811631
    Solaris (SPARC)    U811632
    Solaris (x86-64)   U811633
    iSeries            SI27288
    Linux (x86)        U811634
    Linux (x86-64)     U811635
    Linux (zSeries)    U811636
    Linux (Power)      U811637
    Linux (s390x)      U811638
    
    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

    IY97558

  • Reported component name

    WMQ LIN X86 V6

  • Reported component ID

    5724H7204

  • Reported release

    600

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2007-04-18

  • Closed date

    2007-05-21

  • Last modified date

    2007-07-27

  • 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 V6

  • Fixed component ID

    5724H7204

Applicable component levels

  • R600 PSY

       UP

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Document Information

Modified date:
27 July 2007