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PM30455: CICS REGION STALLS OR HANGS DUE TO A DEADLOCK OCCURRING BETWEEN THE XMLOCK AND SMLOCK. TASKS SUSPENDED IN LMQUEUE WAITS

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APAR status

  • Closed as program error.

Error description

  • You are running CICS Transaction server 3.1 and your
    region hangs.  A dump taken at this time shows many
    tasks suspended in LMQUEUE waits.  The majority of
    these are waiting on the SMLOCK or the XMLOCK.
    This APAR is similar to PK67128 and PK93994, except
    the module here is DFHSMGF instead of DFHSMMF and DFHSMAR.
    In this scenario task A is returning from a link, so module
    DFHSMGF is called to freemain a piece of storage. This
    caused it to obtain the storage manager lock or SMLOCK.
    This piece of storage has been found to have a corrupted
    check zone, so now calls DFHXMIQ to issue a SET_TRANSACTION
    function to increment the storage violation count.
    This requires the XMLOCK, which is not available, so
    this task is now in an LMQUEUE wait.
    Then task B is simply in the process of terminating and
    DFHXMTA requests the XMLOCK, which is not available
    so it gets suspended in an LMQUEUE wait also.
    .
    When the XMLOCK now becomes available, task B happens
    to get it, and now attempts to freemain task storage
    which requires the SMLOCK... which task A still owns.
    These 2 tasks are now in a deadlock condition and other tasks
    start backing up behind them in LMQUEUE waits.
    KIXREVEPH
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All.                                         *
    ****************************************************************
    * PROBLEM DESCRIPTION: Deadlock between two tasks caused by    *
    *                      conflicting XMLOCK and SMLOCK requests. *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    There is a deadlock between a transaction that owns the SMLOCK
    and is waiting for the XMLOCK to be freed and another that owns
    the XMLOCK and is waiting for the SMLOCK to be freed.
    
    (1) Following a storage violation, procedure
    storage_check_failure in DFHSMGF is called.  This holds the
    SMLOCK.
    (2) A transaction manager SET_TRANSACTION call is made to
    update the number of storage violations which have occurred for
    the task.  This requires the XMLOCK.
    (3) At the same time a problem has occurred during the detach of
    another task.  This holds the XMLOCK.
    (4) Procedure free_transaction in DFHXMAT is called to make a
    storage manager FREEMAIN call to free storage in the transaction
    subpool.  This requires the SMLOCK.
    
    Additional Keywords: SM XM MSGDFHSM0102 DFHSM0102 SM0102
    

Problem conclusion

  • Procedure storage_check_failure in DFHSMGF has been changed to
    release and reacquire the SMLOCK around the transaction manager
    SET_TRANSACTION call.
    

Temporary fix

  •             *********
                * HIPER *
                *********
    FIX AVAILABLE BY PTF ONLY
    

Comments

APAR Information

  • APAR number

    PM30455

  • Reported component name

    CICS TS Z/OS V4

  • Reported component ID

    5655S9700

  • Reported release

    600

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2011-01-14

  • Closed date

    2011-01-26

  • Last modified date

    2011-02-02

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

    PM29909

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

    UK64123

Modules/Macros

  •    DESSMGF  DFHSMGF
    

Fix information

  • Fixed component name

    CICS TS Z/OS V4

  • Fixed component ID

    5655S9700

Applicable component levels

  • R600 PSY UK64123

       UP11/02/01 P F101

Fix is available

  • Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.

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Document Information

Modified date:
02 February 2011