IBM Support

IT07964: WMQ MULTITHREADED JAVA APPLICATION THROWS NULLPOINTEREXCEPTION WHEN USING CCDT

Subscribe to this APAR

By subscribing, you receive periodic emails alerting you to the status of the APAR, along with a link to the fix after it becomes available. You can track this item individually or track all items by product.

Notify me when this APAR changes.

Notify me when an APAR for this component changes.

 

APAR status

  • Closed as program error.

Error description

  • A WebSphere MQ classes for Java application throws a
    java.lang.NullPointerException when two (or more) threads
    attempt to establish a connection to WebSphere MQ using the same
    CCDT URL. The stack of the exception is:
    
    java.lang.NullPointerException
     at
    com.ibm.mq.jmqi.remote.internal.RemoteFAP.jmqiConnect(RemoteFAP.
    java:1697)
     at
    com.ibm.mq.jmqi.remote.internal.RemoteFAP.jmqiConnect(RemoteFAP.
    java:1305)
     at com.ibm.mq.MQSESSION.MQCONNX_j(MQSESSION.java:924)
     at
    com.ibm.mq.MQManagedConnectionJ11.(MQManagedConnectionJ11.
    java:233)
     at
    com.ibm.mq.MQClientManagedConnectionFactoryJ11._createManagedCon
    nection(MQClientManagedConnectionFactoryJ11.java:487)
     at
    com.ibm.mq.MQClientManagedConnectionFactoryJ11.createManagedConn
    ection(MQClientManagedConnectionFactoryJ11.java:529)
     at
    com.ibm.mq.StoredManagedConnection.(StoredManagedConnectio
    n.java:96)
     at
    com.ibm.mq.MQSimpleConnectionManager.allocateConnection(MQSimple
    ConnectionManager.java:208)
     at
    com.ibm.mq.MQQueueManagerFactory.obtainBaseMQQueueManager(MQQueu
    eManagerFactory.java:882)
     at
    com.ibm.mq.MQQueueManagerFactory.procure(MQQueueManagerFactory.j
    ava:772)
     at
    com.ibm.mq.MQQueueManagerFactory.constructQueueManager(MQQueueMa
    nagerFactory.java:723)
     at
    com.ibm.mq.MQQueueManagerFactory.createQueueManager(MQQueueManag
    erFactory.java:173)
     at
    com.ibm.mq.MQQueueManager.(MQQueueManager.java:1066)
     ... ...
    

Local fix

  • Do not share a CCDT file across multiple threads.
    
    For example, if using the WebSphere MQ classes for Java, you can
    pass the CCDT file as a URL value on the constructor of the
    class:
    
    com.ibm.mq.MQQueueManager(
            java.lang.String queueManagerName,
            java.util.Hashtable properties,
            java.net.URL url
    )
    
    If you copy the CCDT file to a new file for each new thread
    which is creating the MQQueueManager object, and pass that new
    file URL into each contructor's argument, the problem is worked
    around.
    

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    This issue affects users of the WebSphere MQ classes for JMS or
    classes for Java who create multiple connections to WebSphere MQ
    using the same CCDT file.
    
    
    Platforms affected:
    MultiPlatform
    
    ****************************************************************
    PROBLEM DESCRIPTION:
    A timing windows existed in the WebSphere MQ classes for JMS and
    classes for Java whereby two threads could share and manipulate
    the same MQCD structure, parsed from a CCDT file. This resulted
    in the following processing:
    
    
    Thread 1:
        Check Property A on the MQCD object is not null.
    
    Thread 2:
        Check Property A on the MQCD object is not null.
    
    Thread 1:
        Perform some action on Property A from the MQCD object
    
    Thread 1:
        Set Property A on the MQCD object to null.
    
    Thread 2:
        Perform some action on Property A from the MQCD object.
    
    
    The last in the above steps resulted in a
    java.lang.NullPointerException to be thrown on Thread 2, because
    Thread 1 set the MQCD property to null between Thread 2 having
    checked whether the property was null and then performing some
    action on it.
    

Problem conclusion

  • The WebSphere MQ classes for JMS and classes for Java have been
    updated such that each thread creates a copy of the MQCD object,
    parsed from a shared CCDT file, to use when establishing a
    connection to WebSphere MQ.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
    Version    Maintenance Level
    v7.0       7.0.1.14
    v7.1       7.1.0.7
    v7.5       7.5.0.6
    v8.0       8.0.0.4
    
    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

    IT07964

  • Reported component name

    WMQ WINDOWS V7

  • Reported component ID

    5724H7220

  • Reported release

    701

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2015-03-26

  • Closed date

    2015-06-30

  • Last modified date

    2015-06-30

  • 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

  • R701 PSY

       UP

[{"Business Unit":{"code":"BU048","label":"IBM Software"},"Product":{"code":"SSCPQ63","label":"APAR \/ Maintenance"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"7.0.1","Edition":"","Line of Business":{"code":"","label":""}}]

Document Information

Modified date:
30 June 2015