IBM Support

PI64757: MQMSTR HIGH CPU CONSUMPTION AND FLOOD OF MESSAGES IGD103I IGD104I RELATED TO BSDS AND LOG OF A STOPPED MEMBER OF QSG

A fix is available

Subscribe

You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • Customer has a QSG where member CSQ1 is active, and member CSQ2
    is dormant.
    
    
    There is an XA client which is issuing an XA Recover.
    
    As the Qmanager is in a queue-sharing group it needs to find
    indoubt URs from all queue-managers in the group.
    As CSQ2 is not active, CSQ1 does this by reading the logs of
    CSQ2, which results in CSQ2's BSDS being  dynamically allocated
    etc.
    CSQ1 then returns a number of URIDs for the XA Recover.
    However, the number of indoubt URs exceeds the size of the
    buffer given on the XA Recover (15 in this case).
    The XA Recover is then issued again to obtain the remaining
    indoubt URs.
    However, the queue-manager returns the same set of URIDs.
    This then results in the high CPU and CSQ2's BSDS etc being
    continually allocated/deallocated as the XA Recover is issued
    over and over by the client.
    .
    Additional keywords:
    performance loop looping
    

Local fix

  • n/a
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 8 *
    *                 Release 0 Modification 0.                    *
    ****************************************************************
    * PROBLEM DESCRIPTION: High CPU and/or IO when a transactional *
    *                      client issues xa_recover at the qsg     *
    *                      scope and there are more indoubt XID's  *
    *                      than will fit in the buffer provided by *
    *                      the client.                             *
    *                      Depending on the state of the other     *
    *                      queue managers in the qsg, message      *
    *                      IGD104I may also be written to JESYSMSG *
    *                      repeatedly.                             *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    A transaction client connected to a queue manager with GROUPUR
    enabled using the qsg name and then issued xa_recover with the
    TMSTARTRSCAN flag set to get a list of indoubt XIDs.
    CSQMXARH detected that the client was connected at qsg scope
    and called CSQMCIGI to get a list of indoubt XIDs for all
    queue managers in the QSG, before copying the XIDs back to the
    client's buffer, until the buffer was full.
    The client processed the XIDs in the buffer and then reissued
    xa_recover without TMSTARTRSCAN to get the next batch of XIDs.
    However, CSQMXARH incorrectly determined that this was not
    a continuation of the earlier scan and called CSQMCIGI again
    before returning the same XIDs as the previous call.
    This led to the client continually reissuing the xa_recover
    call and receiving the same XIDs over and over.
    Each time CSQMCIGI is called, the BSDS for inactive queue
    managers was allocated and deallocated, leading to the
    repeated IGD104I messages in JESYSMSG.
    

Problem conclusion

  • CSQMXARH is changed to correctly continue the scan from the next
    XID to be returned.
    000Y
    CSQMXARH
    

Temporary fix

  • *********
    * HIPER *
    *********
    

Comments

APAR Information

  • APAR number

    PI64757

  • Reported component name

    WMQ Z/OS 8

  • Reported component ID

    5655W9700

  • Reported release

    000

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2016-06-24

  • Closed date

    2016-06-29

  • Last modified date

    2016-08-02

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

    PI59217

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

    UI39035

Modules/Macros

  • CSQMXARH
    

Fix information

  • Fixed component name

    WMQ Z/OS 8

  • Fixed component ID

    5655W9700

Applicable component levels

  • R000 PSY UI39035

       UP16/07/28 P F607 ¢

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.

[{"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSYHRD","label":"IBM MQ"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"8.0","Edition":"","Line of Business":{"code":"LOB36","label":"IBM Automation"}}]

Document Information

Modified date:
02 August 2016