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PI68940: MQ V900 - HIGH CPU CONSUMPTION IN MODULE CSQLLPLM.

A fix is available

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APAR status

  • Closed as program error.

Error description

  • High CPU consumption in module CSQLLPLM.
    
    It occurs when an application browses messages on the queue,
    and then closes the queue with the delete-purge option. The
    IS allocation page lock that browse processing obtained prior
    to the close of the queue is not released, causing the problem
    seen with high CPU in CSQLLPLM.
    

Local fix

  • n/a
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All users of IBM MQ for z/OS Version 9 Release 0             *
    * Modification 0.                                              *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * High CPU in load module CSQLLPLM due to a build up of        *
    * allocation locks on pages used by dynamic queues.            *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * none                                                         *
    ****************************************************************
    When browsing a dynamic queue, an application obtained an
    allocation lock on the pages currently under the browse cursor.
    When the application closed the queue it specified that the
    dynamic queue should be deleted (e.g. passing MQCO_DELETE_PURGE
    to MQCLOSE), and so CSQMCLS2 called CSQIDDEL to delete the
    queue. When this returned CSQMCLS2 called CSQIMBLR to release
    the locks under the browse cursor, however because the IVSA for
    the queue no longer existed CSQIMBLR could not determine if the
    queue was private or shared, and so skipped releasing the locks.
    
    Over time the number of allocation locks that had not been
    correctly released by a long running application can build up,
    leading to high CPU in CSQLLPLM while searching long chains of
    lock control blocks.
    

Problem conclusion

  • CSQIMBLR is changed to correctly release the allocation locks
    when called as part of a close operation that also deletes the
    dynamic queue.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PI68940

  • Reported component name

    MQ Z/OS V9

  • Reported component ID

    5655MQ900

  • Reported release

    000

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2016-09-09

  • Closed date

    2016-09-26

  • Last modified date

    2017-05-19

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

    PI68172

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

    UI41081

Modules/Macros

  • CSQIMBLR CSQMCLS2
    

Fix information

  • Fixed component name

    MQ Z/OS V9

  • Fixed component ID

    5655MQ900

Applicable component levels

  • R000 PSY UI41081

       UP16/10/14 P F610

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:
19 May 2017