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IC69703: WMQ EXPLORER HANGS WITH PROBE ID JU:40010, WHILE TRACING IS ENABLED AND THE WMQFTE TRANSFER LOG IS LOST.

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APAR status

  • Closed as program error.

Error description

  • The WebSphere MQ Explorer is hanging and loosing the WebSphere
    MQ File Transfer Edition transfer log. The FDC files generated
    at the time of the hang indicate "Failed to create content
    page." The probe id for MQ is JU:40010.
    
    The problem is only seen when WebSphere MQ tracing is enabled.
    Even then, the hang is mainly experienced when wrapping
    trace is used.
    

Local fix

  • Avoid running a wrapping WebSphere MQ trace.
    

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    All users of WebSphere MQ on the Windows platform who enable
    wrapping trace.
    
    Platforms affected:
    Windows
    
    ****************************************************************
    PROBLEM SUMMARY:
    The problem occurs due to a deadlock between two threads as
    follows:
    
    1) Thread A has just entered DllMain in the transaction manager
    component on Windows (amqmtmgr) and is attempting to write a
    trace point. As a result, it currently holds the loader lock
    (because it is in DllMain) and is blocked waiting on the trace
    lock to become available.
    
    2) Meanwhile, thread B has already entered a trace point and
    grabs the trace lock. At this point, it determines that it is
    now time for the trace files to wrap so it attempts to write a
    new trace file header. The trace header includes some OS
    specific data retrieved from function xcsGetHostInfo. This
    includes attempts to load system library kernel32.dll and so, it
    attempts to acquire the loader lock. However, thread A already
    has the loader lock hence the deadlock.
    
    Even with trace, the problem should not occur very often as it
    relies on a timing window where the trace files are wrapped at
    the same time as another thread is entering DllMain for one of
    the MQ dlls.
    

Problem conclusion

  • Code change ensures that the deadlock does not occur between
    the threads thus preventing the hang in the application process.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
                       v7.0
    Platform           Fix Pack 7.0.1.3
    --------           --------------------
    Windows            U200320
    
    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

    IC69703

  • Reported component name

    WMQ WINDOWS V7

  • Reported component ID

    5724H7220

  • Reported release

    701

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2010-07-06

  • Closed date

    2010-07-20

  • Last modified date

    2010-07-20

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

    IC68773

  • 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

  • R701 PSY

       UP

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Document Information

Modified date:
20 July 2010