IBM Support

IT20481: MultiInstance Queue Manager failover may cause .Net client to send duplicate message

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APAR status

  • Closed as program error.

Error description

  • In a .Net client, with the automatic reconnect option ON, if a
    queue manager failover happens when the client is sending
    messages then in some cases a duplicate message is delivered by
    the queue manager.
    

Local fix

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    Users of Managed .Net clients with reconnect option ON which
    connects to a multi instance queue manager.
    
    
    Platforms affected:
    Windows
    
    ****************************************************************
    PROBLEM DESCRIPTION:
    When a Managed .Net client connects to a multi-instance queue
    manager with auto reconnect option specified, then the client
    layer will receive notification when the queue manager fails
    over. If the failover happened while the client was sending a
    non-persistent message and before the reply was received, then
    for non-transacted session, an omission in this logic meant that
    the message was sent twice. Once before the queue manager failed
    over, and for a second time after the client had reconnected.
    

Problem conclusion

  • The .Net code has been modified so that, if automatic client
    reconnection occurs while sending a non-persistent message then
    the client will reconnect to the queue manager and:
    - Return from the method normally, if its a non-transacted
    session used to put a non-persistent message.
    - Throw an Exception containing reason code 2003
    (MQRC_BACKED_OUT) from a transacted session.
    - Throw an Exception containing reason code 2549
    (MQRC_CALL_INTERRUPTED) in all other situations.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
    Version    Maintenance Level
    v8.0       8.0.0.11
    v9.0 LTS   9.0.0.6
    v9.1 CD    9.1.1
    v9.1 LTS   9.1.0.1
    
    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

    IT20481

  • 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

    2017-05-05

  • Closed date

    2018-11-15

  • Last modified date

    2019-03-15

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

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

Fix information

  • Fixed component name

    WMQ BASE MULTIP

  • Fixed component ID

    5724H7251

Applicable component levels

[{"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSYHRD","label":"IBM MQ"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"8.0.0.0","Edition":"","Line of Business":{"code":"LOB36","label":"IBM Automation"}}]

Document Information

Modified date:
15 March 2019