IBM Support

IT22180: MQ channel status shows incorrect value of "*" for the MCAUSER when multiple conversations start concurrently.

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APAR status

  • Closed as program error.

Error description

  • The DISPLAY CHSTATUS(CHANNEL_NAME) shows an '*' for the MCAUSER
    instead of the correct userid to which it is set.
    

Local fix

  • The USERSRC() value on the rule can be changed to USERSRC(MAP)
    (which is the default value) and then set the MCAUSER parameter
    on the rule to the same value as the CLNTUSER().  For example,
    instead of setting the rule with the command:
    
    SET CHLAUTH('My.Channel.SVC') TYPE(USERMAP) CLNTUSER('User123')
         USERSRC(CHANNEL) CHCKCLNT(REQUIRED) ACTION(REPLACE)
    
    you use the following command instead :
    
    SET CHLAUTH('My.Channel.SVC') TYPE(USERMAP) CLNTUSER('User123')
    MCAUSER('User123') CHCKCLNT(REQUIRED) ACTION(REPLACE)
    

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    This issue affects users of WebSphere MQ V8 and IBM MQ V9 who
    use multiplexed channels together with the queue manager setting
    ChlauthEarlyAdopt=y.
    
    
    Platforms affected:
    MultiPlatform
    
    ****************************************************************
    PROBLEM DESCRIPTION:
    The DISPLAY CHSTATUS(CHANNEL_NAME) shows an '*' for the MCAUSER
    instead of the correct userid to which it is set.
    A race condition occurs in channel initialisation
    caused at a point where the channel status is progressing
    through a sequence of states. Normally, the MCAUSER in the
    channel status is temporarily set to the user defined on  the
    channel (e.g. NOACCESS), then later updated to the correct
    (adopted) user id (e.g. User123).
    
    We see the problematic case when multiple conversations are
    starting concurrently.  There is a timing window when a
    conversation has set MCAUSER status to the  temporary user
    (NOACCESS) and another conversation begins.  When this
    happens, MQ compares the conversation userid with the
    userid in channel status, realizes they are different and
    incorrectly sets the overall MCAUSER for the channel status
    to "*".
    

Problem conclusion

  • The MQ channel code has been modified to ensure the MCAUSER
    in the channel status is updated correctly when this timing
    condition
    arises.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
    Version    Maintenance Level
    v8.0       8.0.0.9
    v9.0 CD    9.0.5
    v9.0 LTS   9.0.0.3
    
    The latest available maintenance can be obtained from
    'WebSphere MQ Recommended Fixes'
    http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
    
    If the maintenance level is not yet available information on
    its planned availability can be found in 'WebSphere MQ
    Planned Maintenance Release Dates'
    http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
    ---------------------------------------------------------------
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT22180

  • Reported component name

    WMQ BASE MULTIP

  • Reported component ID

    5724H7251

  • Reported release

    800

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2017-08-28

  • Closed date

    2017-10-31

  • Last modified date

    2017-10-31

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

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

    PI89616

Fix information

  • Fixed component name

    WMQ BASE MULTIP

  • Fixed component ID

    5724H7251

Applicable component levels

  • R800 PSY

       UP

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Document Information

Modified date:
31 October 2017