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IT19521: MQ V8 - TELEMETRY CHANNEL - FDC WITH PROBEID XR051002 FILLING THE FILE SYSTEM.

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APAR status

  • Closed as program error.

Error description

  • Customer observes 2 issues:
    
    - A large number of FDCs being generated by the MQ Telemetry
    channel, with probeID XR051002, and Exception cause
    
        "java.lang.Exception: mqcd<mqsc>:json at
    com.ibm.mq.MQXRService.MQTransmitQueueMessage
    	parseRfh2(MQTransmitQueueMessage.java:798)"
    
    - A build up of messages on the SYSTEM.MQTT.TRANSMIT.QUEUE and
    very slow performances.
    

Local fix

  • n/a
    

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    This issue affects users of:
    
    - The MQ V8 Telemetry channel.
    - The MQ V9 Telemetry channel.
    
    who have:
    
    - MQ TT clients which publish messages on a topic, where the
    messages have the "Msd" field within the <mcd> folder within the
    MQRFH2 header set to a value other than the ones shown below:
    
        - jms_bytes
        - jms_map
        - jms_none
        - jms_object
        - jms_stream
        - jms_text
        - mrm
        - xmlnsc
        - xmlns
        - xml
        - mime
        - idoc
        - none
    
    - And MQ TT clients that subscribe to the same topic.
    
    
    Platforms affected:
    MultiPlatform
    
    ****************************************************************
    PROBLEM DESCRIPTION:
    When the MQ Telemetry channel is given a message to forward on
    to an MQTT subscriber, it looks at the Msd field within the
    <mcd> folder in the MQRFH2 header for the message to determine
    how to treat the message payload. The MQ Telemetry channel
    expects this field to have one of the following values:
    
    - jms_bytes
    - jms_map
    - jms_none
    - jms_object
    - jms_stream
    - jms_text
    - mrm
    - xmlnsc
    - xmlns
    - xml
    - mime
    - idoc
    - none
    
    If the Msd field was set to a different value, then the MQ
    Telemetry channel would treat the message payload as bytes when
    forwarding it on to an MQ TT subscriber. However, the channel
    would also generate an FDC containing probe identifier XR051002.
    
    If every message that was processed by the MQ Telemetry channel
    had the Msd field set to an unexpected value, then it would
    generate an FDC for every message. As well as filling up the
    file system on the machine where the queue manager was running,
    this also affected the performance of the MQ Telemetry channel
    (generating an FDC is quite a performance intensive operation)
    which resulted in messages building up on the system queue
    SYSTEM.MQTT.TRANSMIT.QUEUE used by the channel.
    

Problem conclusion

  • The MQ Telemetry channel has been updated so that it does not
    generate an FDC if it is asked to process a message where the
    Msd field within the <msd>folder within the MQRFH2 header of a
    message is set to an unexpected value.
    
    FDCs should only be generated for errors that are severe, and
    potentially unrecoverable, and they usually indicate either a
    configuration issue or an internal problem with an MQ component.
    In this case, the MQ Telemetry channel has been asked to process
    a message which has an unexpected format. The channel is able to
    process this message, so the error is not unrecoverable, and
    there is no internal MQ issue or configuration issue, which
    means that an FDC is not required here.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
    Version    Maintenance Level
    v8.0       8.0.0.7
    v9.0 LTS   9.0.0.2
    
    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

    IT19521

  • 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

    2017-03-09

  • Closed date

    2017-03-27

  • Last modified date

    2017-03-27

  • 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

  • R800 PSY

       UP

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Document Information

Modified date:
27 March 2017