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IT24782: WebSphere MQ classes for JMS generate FFDC containing probe ID JO136001 when the queue manager they are using stops

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APAR status

  • Closed as program error.

Error description

  • A WebSphere MQ V7.1 classes for JMS application is connecting to
    a queue manager using the CLIENT transport. If the queue manager
    is stopped while the application is still running, the WebSphere
    MQ classes for JMS intermittently throw a JMSException
    containing WebSphere MQ reason code 2195 (MQRC_UNEXPECTED_ERROR)
    and generate an FFDC containing the following information:
    
    **************************************************************
    JMS Common Client First Failure Symptom Report
    
    Source Class :- com.ibm.mq.jmqi.remote.impl.RemoteSession
    Source Method :- receiveMQIFlow(RemoteTls)
    ProbeID :- JO136001
    
    Stack trace -----------
    Stack trace to show the location of the FFST call
     | FFST Location :- java.lang.Exception
     | at
    com.ibm.msg.client.commonservices.trace.Trace.getCurrentPosition
    (Trace.java)
     | at
    com.ibm.msg.client.commonservices.trace.Trace.createFFSTString(T
    race.java:)
     | at
    com.ibm.msg.client.commonservices.trace.Trace.ffstInternal(Trace
    .java)
     | at
    com.ibm.msg.client.commonservices.trace.Trace.ffst(Trace.java)
     | at
    com.ibm.mq.jmqi.remote.impl.RemoteSession.receiveMQIFlow(RemoteS
    ession.java)
        :    :    :    :    :    :    :    :    :    :    :    :
       :    :
    **************************************************************
    

Local fix

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    This issue affects users of:
    
    - The WebSphere MQ classes for Java.
    - The WebSphere MQ classes for JMS.
    - The WebSphere MQ resource adapter.
    
    who have applications that connect to a queue manager using the
    CLIENT transport and WebSphere MQ messaging provider normal
    mode.
    
    
    Platforms affected:
    MultiPlatform
    
    ****************************************************************
    PROBLEM DESCRIPTION:
    The Java Message Queueing Interface (JMQI) is a component of
    the:
    
    - WebSphere MQ classes for Java.
    - WebSphere MQ classes for JMS.
    - WebSphere MQ resource adapter
    
    that handles all of the communication with a queue manager.
    Whenever an application using either the WebSphere MQ classes
    for Java, classes for JMS or resource adapter calls a method
    that requires an MQ  API call to be flowed to the queue manager,
    then the JMQI will make the MQ API call on behalf of the
    application, and process the response that comes back from the
    queue manager.
    
    If an application connects to a queue manager using:
    
    - The CLIENT transport.
    - And WebSphere MQ messaging provider normal mode.
    
    then the JMQI will send the MQ API call to the queue manager on
    the application thread. It will then use an internal Remote
    Receive Thread to pick up the response.
    
    There is one internal Remote Receive Thread per channel instance
    (or TCP/IP connection, if you prefer to think of channel
    instances in those terms). When the Remote Receive Thread
    receives data from a queue manager, it will either process the
    data itself or pass it off to another thread (either the
    application thread or another internal thread).
    
    Now, when an application connected to a queue manager using:
    
    - The CLIENT transport
    - And WebSphere MQ messaging provider normal mode
    
    then when the queue manager was shut down, it sent two internal
    data flows to the JMQI:
    
    - The first data flow was a notification indicating that the
    queue manager had been stopped.
    - The second data flow was an status event, indicating that the
    channel had been closed.
    
    When the Remote Receive Thread received the notification, it
    started a new internal thread to process it. This internal
    thread informed all of the application threads that were using
    the channel instance associated with the Remote Receive Thread
    that the queue manager is no longer available, which caused any
    MQ API calls that were in progress on the application threads to
    fail.
    
    Next, the Remote Receive Thread picked up the status event, and
    passed it directly on the application threads.
    
    Because the internal thread that was processing the notification
    was running at the same time as the Remote Receive Thread was
    processing the status event, there was a small timing window
    where an application thread, that had issued an MQ API call and
    was waiting for a response, was given the status event before
    the internal thread had notified it that the queue manager was
    no longer running. The application thread was not expecting to
    receive the status event at this time, and threw an exception
    containing WebSphere MQ reason code 2195:
    
    MQRC_UNEXPECTED_ERROR
    
    back to the application, and generated an FFDC. An example of
    the FFDC is shown below:
    
    **************************************************************
    JMS Common Client First Failure Symptom Report
    
    Source Class :-
      com.ibm.mq.jmqi.remote.impl.RemoteSession
    Source Method :- receiveMQIFlow(RemoteTls)
    ProbeID :- JO136001
    
    Stack trace -----------
    Stack trace to show the location of the FFST call
     | FFST Location :- java.lang.Exception
     | at
    com.ibm.msg.client.commonservices.trace.Trace.getCurrentPosition
    (Trace.java)
     | at
    com.ibm.msg.client.commonservices.trace.Trace.createFFSTString(T
    race.java:)
     | at
    com.ibm.msg.client.commonservices.trace.Trace.ffstInternal(Trace
    .java)
     | at
    com.ibm.msg.client.commonservices.trace.Trace.ffst(Trace.java)
     | at
    com.ibm.mq.jmqi.remote.impl.RemoteSession.receiveMQIFlow(RemoteS
    ession.java)
        :    :    :    :    :    :    :    :    :    :    :    :
       :    :
    **************************************************************
    

Problem conclusion

  • The JMQI has been updated to ignore any status events that are
    passed to an application thread for processing. This allows the
    application thread to continue waiting for a response to an MQ
    API call.
    
    Once the JMQI has processed the notification asynchronously, the
    application thread will be informed that the queue manager is no
    longer accessible - this causes it to stop waiting, and fail
    with an exception containing an appropriate WebSphere MQ reason
    code, such as 2161:
    
    MQRC_Q_MGR_QUIESCING
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
    Version    Maintenance Level
    v7.5       7.5.0.9
    v8.0       8.0.0.11
    v9.0 LTS   9.0.0.5
    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

    IT24782

  • Reported component name

    WMQ WINDOWS V7

  • Reported component ID

    5724H7220

  • Reported release

    710

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2018-04-19

  • Closed date

    2018-06-08

  • Last modified date

    2018-07-20

  • 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 WINDOWS V7

  • Fixed component ID

    5724H7220

Applicable component levels



Document information

More support for: WebSphere MQ
APAR / Maintenance

Software version: 710

Reference #: IT24782

Modified date: 20 July 2018


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