IBM Support

PI74030: WMQ: EXCESSIVE STORAGE ALLOCATION AND FREE OPERATIONS FOR SVRCONN CHANNELS WITH A SHARECNV VALUE GREATER THAN ZERO

A fix is available

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APAR status

  • Closed as program error.

Error description

  • Excessive storage allocation and free operations for SVRCONN
    channels with a SHARECNV value greater than zero
    .
    Additional Symptom(s) Search Keyword(s):
    CHIN trace has many CSQXGETS calls obtaining 688 or 0x2B0 bytes
    for rstSTREAMQUEUE storage, which has an eyecatcher of RSTQ .
    .
    MQOPEN MQCLOSE performance
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All users of IBM MQ for z/OS Version 9 Release 0             *
    * Modification 0.                                              *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * Increased CPU usage in Chinit when using SVRCONNs with       *
    * SHARECNV greater than zero with workload that frequently     *
    * opens and closes queues.                                     *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * When a SVRCONN channel is using shared conversations and is  *
    * frequently opening and closing queues, additional storage    *
    * for control blocks is regularly obtained and released. While *
    * this is correct behavior, applications that perform a large  *
    * number of queue open and close operations may find that the  *
    * additional overhead of this storage management begins to     *
    * have an impact on Chinit performance exhibiting high CPU in  *
    * IGVGPVT.                                                     *
    ****************************************************************
    

Problem conclusion

  • Some control blocks associated with opening and closing queues
    have been moved to z/OS cellpools to improve efficiency.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PI74030

  • Reported component name

    MQ Z/OS V9

  • Reported component ID

    5655MQ900

  • Reported release

    000

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2016-12-20

  • Closed date

    2017-01-18

  • Last modified date

    2017-03-02

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

    PI73537

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

    UI44033

Modules/Macros

  • CMQXRSTF CSQXJST  None
    

Fix information

  • Fixed component name

    MQ Z/OS V9

  • Fixed component ID

    5655MQ900

Applicable component levels

  • R000 PSY UI44033

       UP17/02/08 P F702

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 March 2017