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PI69443: MQ Z/OS - HIGH CPU CONSUMPTION IN CHIN

A fix is available

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APAR status

  • Closed as program error.

Error description

  • A negative recv() timeout value is being calculated as the
    interval between the current time and the time that some
    non-heartbeat data was last received is greater than the
    configured DISCINT value for client channel. This negative
    recv() timeout value results in the high CPU in the CHIN.
    

Local fix

  • The problem could be circumvented by setting DISCINT to 0 for
    SVRCONN
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All users of IBM MQ for z/OS Version 9 Release 0             *
    * Modification 0.                                              *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * High CPU usage reported in CHIN when using SHARECNV>0        *
    * SVRCONN channels with disconnect interval configured.        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * N/A                                                          *
    ****************************************************************
    Client applications executing MQGET with unlimited or very long
    wait intervals connected using SHARECNV >0 SVRCONN channels with
    disconnect interval (DISCINT) configured with a value smaller
    than the MQGET WAIT interval can cause the invocation of TCPIP
    receive calls with negative timeout values causing the receive
    to return immediately with a reason code indicating that timeout
    interval has expired resulting in a loop of receive calls
    expecting data or a heartbeat message or DISCINT to expire. This
    loop causes the high CPU usage observed.
    

Problem conclusion

  • CSQXCCAX (cciReceiveOne) has been changed to prevent passing
    negative timeout intervals to the TCP IP receive calls avoiding
    the loop.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PI69443

  • 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

    2016-09-20

  • Closed date

    2016-09-27

  • Last modified date

    2016-11-02

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

    PI62878

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

    UI41144

Modules/Macros

  • CSQXCCAX
    

Fix information

  • Fixed component name

    MQ Z/OS V9

  • Fixed component ID

    5655MQ900

Applicable component levels

  • R000 PSY UI41144

       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:
02 November 2016