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PH35786: SLOW SHUTDOWN OF CHINIT WITH LARGE NUMBER OF SVRCONN INSTANCES ACTIVE

A fix is available

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APAR status

  • Closed as program error.

Error description

  • There is an issue with the way that SVRCONN channels are
    stopped during chinit shutdown processing.
    After a STOP QMGR MODE(QUIESCE), the svrconn channels are not
    interrupted. This leaves the DPRO for the channel waiting in a
    receive on the TCP/IP socket, waiting for a request to arrive
    from the client.
    .
    Then a STOP QMGR MODE(FORCE) command causes the chinit to begin
    interrupting the waiting svrconn channels, but the processing
    is only interrupting one channel instance per second as
    indicated by CSQX208E messages
    .
    Where there are a large number of svrconn instances active,
    this results in chinit shutdown taking an extended period of
    time.
    .
    Eventually, the chinit decides that the channels are taking too
    long to stop, and disconnects all the adapter tasks from the
    qmgr. This allows the MSTR task to end, while the chinit is
    still dealing with the remaining channel instances.
    .
    The following messages can be found in CHIN job log if the
    CHINIT is stopped after the MSTR:
    CSQX008E +QMGR CSQXIDEN Unable to disconnect from queue manager
    MQD2, MQCC=2 MQRC=2009 (MQRC_CONNECTION_BROKEN)
    CSQX035I +QMGR CSQXCRPS Connection to queue manager MQD2
    stopping or broken, MQCC=2 MQRC=2009 (MQRC_CONNECTION_BROKEN)
    .
    Additional symptoms:
    As part of STOP CHINIT processing, all active channels are
    stopped before shared channel recovery begins. This means that
    channels stopping slowly can result in a delay in shared
    channel recovery being initiated.
    

Local fix

  • N/A
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
    *                 Release 1 Modification 0 and Release 2       *
    *                 Modification 0.                              *
    ****************************************************************
    * PROBLEM DESCRIPTION: During QMGR Termination, the SVRCONN    *
    *                      channels are not interrupted. Even when *
    *                      using MODE(FORCE), the channels are     *
    *                      only interrupted one per second,        *
    *                      causing Channel Initiator shutdown to   *
    *                      take much longer than expected,         *
    *                      sometimes longer than the MASTER        *
    *                      address space takes to end.             *
    ****************************************************************
    A code defect in the Channel Shutdown process caused the
    SVRCONN channels to only be interrupted at a rate of one per
    second, after an unreasonably long period of time.
    

Problem conclusion

  • CSQXRSAC has been updated to prevent this issue from occurring.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PH35786

  • Reported component name

    IBM MQ Z/OS V9

  • Reported component ID

    5655MQ900

  • Reported release

    100

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2021-03-29

  • Closed date

    2021-06-29

  • Last modified date

    2023-08-14

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

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

    UI76133 UI76134

Modules/Macros

  • CSQXRSAC
    

Fix information

  • Fixed component name

    IBM MQ Z/OS V9

  • Fixed component ID

    5655MQ900

Applicable component levels

  • R100 PSY UI76134

       UP21/07/19 P F107

  • R200 PSY UI76133

       UP21/07/19 P F107

Fix is available

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Document Information

Modified date:
15 August 2023