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PH18621: IBM MQ Z/OS V9:HIGH CPU IN CHIN AFTER 0C4 ABENDS

A fix is available

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APAR status

  • Closed as program error.

Error description

  • Customer complained high CPU in CHIN after several 0C4 abends:
    ABN=0C4-00000004,LOC=CSQXRCTL.CSQXRFIC
    ABN=0C4-00000004,LOC=CSQXRCTL.CMQXRLNK
    ABN=0C4-00000004,LOC=CSQXSUPR.CMQXRLNK
    ABN=0C4-00000004,LOC=CSQXRCTL.CMQXRMNT
    ABN=0C4-00000004,LOC=CSQXSUPR.CSQXRFIC
    c/t confirmed that the issues being seen on this
    system stem from a corruption in a chain of cluster cache
    blocks. Most of the errors are in a function (rfiAllocCacheArea)
    which  allocates blocks in the cache. Within that code there
    appears to be an issue with the locking of the cache, which
    could potentially result in  corruption to the chains.
    
    Additional Symptom(s) Search Keyword(s):
    ABN=5C6-00E70FFF,LOC=CSQXRCTL.CSQVLSMX
    rfiAllocCacheArea
    

Local fix

  • n/a
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
    *                 Release 0 Modification 0.                    *
    ****************************************************************
    * PROBLEM DESCRIPTION: Various problems can occur on clustered *
    *                      queue managers due to corruption of the *
    *                      cluster cache free lists.               *
    *                                                              *
    *                      Symptoms can include:                   *
    *                      - high CPU usage                        *
    *                      - abend 0C4 in CSQXRFIC                 *
    *                      - abend 0C4 in CMQXRLNK                 *
    *                      - abend 0C4 in CMQXRMNT                 *
    ****************************************************************
    An error in serialisation when looking for free storage areas
    on the fixed size free lists in the cluster cache resulted in
    the same area being allocated to multiple tasks concurrently.
    Depending on how and when those tasks use the returned storage
    blocks, results are unpredictable.
    

Problem conclusion

  • CSQXRFIC has been changed to correct the serialisation error in
    rfiAllocCacheArea.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PH18621

  • Reported component name

    IBM MQ Z/OS V9

  • Reported component ID

    5655MQ900

  • Reported release

    000

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2019-10-29

  • Closed date

    2019-11-08

  • Last modified date

    2019-11-30

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

    PH13728

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

    UI66344

Modules/Macros

  • CSQURFIC CSQXRFIC
    

Fix information

  • Fixed component name

    IBM MQ Z/OS V9

  • Fixed component ID

    5655MQ900

Applicable component levels

  • R000 PSY UI66344

       UP19/11/27 P F911 ¢

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:
30 November 2019