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PM94566: CHIN HANG ON SHUTDOWN DUE TO A LOOP OF THE PUB/SUB DAEMON NAMELISTS.

A fix is available

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APAR status

  • Closed as program error.

Error description

  • A loop has occurred while processing a change to one of
    the pubsub daemon namelists and can cause a hang during
    shutdown of the CHIN.
    .
    There appears to be a timing window where an ALTER or
    DEFINE REPLACE of SYSTEM.QPUBSUB.QUEUE.NAMELIST or
    SYSTEM.QPUBSUB.SUBPOINT.NAMELIST being processed
    at the same time as the pubsub daemon is starting can
    similarly result in duplicate entries being created on
    SYSTEM.HIERARCHY.STATE and result in a loop condition.
    

Local fix

  • Recommendattion to avoid the cpu loop condition:
    
    - clear the following 3 queues to remove any
      invalid entries already created due to the error:
    .
       SYSTEM.HIERARCHY.STATE
       SYSTEM.BROKER.INTER.BROKER.COMMUNICATIONS
       SYSTEM.RETAINED.PUB.QUEUE
    .
    - apply PM83749 (UK94286).
    .
    - if queued pubsub is not being used, setting
      PSMODE(DISABLED) or PSMODE(COMPAT) will prevent
      the pubsub daemon starting, preventing the code
      in error from being executed
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 7 *
    *                 Release 0 Modification 1 and Release 1       *
    *                 Modification 0.                              *
    ****************************************************************
    * PROBLEM DESCRIPTION: 'CSQX053E CSQXFFST Error information    *
    *                      recorded in CSQSNAP data set' is        *
    *                      issued, and an FFST indicating an error *
    *                      in fmiBuildStreamsSupported is written  *
    *                      to the CSQSNAP DD.                      *
    *                      If PM83749 is not applied, a tight      *
    *                      loop in fmiBuildStreamsSupported        *
    *                      will occur instead of the FFST,         *
    *                      leading to high CPU usage in the        *
    *                      channel initiator address space,        *
    *                      and preventing the channel initiator    *
    *                      shutting down when requested.           *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    Insufficient serialisation between the startup of the pubsub
    daemon and notification of a change to one of the pubsub daemon
    namelists allows fnlMonitorNameListchange to execute while the
    daemon is still starting up.
    There is a window where the processing of the notification that
    either SYSTEM.QPUBSUB.QUEUE.NAMELIST or
    SYSTEM.QPUBSUB.SUBPOINT.NAMELIST have changed can cause an
    a thread to start and attempt to create a new stream for
    the streams named in the namelist before they are restarted.
    This leads to the FFST (or loop if PM83749 is not applied),
    and causes duplicate records to be created on
    SYSTEM.HIERARCHY.STATE.
    On subsequent starts of the chinit, the duplicate records
    cause the pubsub daemon to fail on startup, issuing CSQT855E
    with reason 0000588B.
    

Problem conclusion

  • Additional serialisation is added to ensure that notifications
    that the namelists have changed are only processed after the
    daemon has completed startup.
    010Y
    100Y
    CSQXFCTL
    CSQXSPRM
    

Temporary fix

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

Comments

APAR Information

  • APAR number

    PM94566

  • Reported component name

    WMQ Z/OS V7

  • Reported component ID

    5655R3600

  • Reported release

    010

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2013-08-06

  • Closed date

    2013-09-27

  • Last modified date

    2013-11-04

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

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

    UK97989 UK97990

Modules/Macros

  • CSQXFCTL CSQXSPRM
    

Fix information

  • Fixed component name

    WMQ Z/OS V7

  • Fixed component ID

    5655R3600

Applicable component levels

  • R010 PSY UK97989

       UP13/10/16 P F310 Ž

  • R100 PSY UK97990

       UP13/10/16 P F310 Ž

Fix is available

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Document Information

Modified date:
04 November 2013