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IZ65557: WMQ 7 JAVA APPLICATION EXPERIENCES A HANG WHILE CONNECTING TO QUEUE MANAGER USING SHARED CONNECTIONS.

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APAR status

  • Closed as program error.

Error description

  • If connection sharing is in use, a hang occurs if an existing
    connection is being closed when a new connection attempt is
    being made. Since the thread used to receive data is now closed,
    the thread waiting for data, therefore, waits indefinitely.
    Here is a java stack that indicates a problem:
    
    "Thread-382" (TID:0x39650A00, sys_thread_t:0x395BEFD0, state:CW,
    native ID:0x00AD10F5) prio=5
    at java/lang/Object.wait(Native Method)
    at java/lang/Object.wait(Object.java:199)
    at
    com/ibm/mq/jmqi/remote/internal/RemoteHconn.receiveAsyncTsh
    (RemoteHconn.java:1912)
    
    at
    com/ibm/mq/jmqi/remote/internal/RemoteHconn.receiveTSH
    (RemoteHconn.java:1176)
    
    at
    com/ibm/mq/jmqi/remote/internal/system/RemoteConnection
    .addHconn(RemoteConnection.java:891)
    
    at
    com/ibm/mq/jmqi/remote/internal/system/RemoteConnectionPool
    .getConnection(RemoteConnectionPool.java:495(Compiled Code))
    
    "Thread-232" (TID:0x3562DB00, sys_thread_t:0x356797E8, state:CW,
    native ID:0x007DC0C7) prio=5
    at java/lang/Object.wait(Native Method)
    at java/lang/Object.wait(Object.java:199(Compiled Code))
    at
    com/ibm/mq/jmqi/remote/internal/system/RemoteConnection
    .sendTSH(RemoteConnection.java:2185(Compiled Code))
    at
    com/ibm/mq/jmqi/remote/internal/system/RemoteConnection
    .addHconn(RemoteConnection.java:876(Compiled Code))
    at
    com/ibm/mq/jmqi/remote/internal/system/RemoteConnectionPool
    .getConnection(RemoteConnectionPool.java:490(Compiled Code))
    
    
    Another symptom which may also be observed in the logs is the
    following ConcurrentModificationException stack trace:
    
    java.util.ConcurrentModificationException
      at java.util.LinkedList$ListItr.checkForComodification(LinkedL
    ist.java:617)
      at java.util.LinkedList$ListItr.next(LinkedList.java:552)
      at com.ibm.mq.jmqi.remote.internal.system.RemoteConnectionPool
    .getConnection(RemoteConnectionPool.java:173)
    

Local fix

  • Disable connection sharing.
    The following line should be used to set the property:
    
    m_mqProperties.put(MQC.SHARING_CONVERSATIONS_PROPERTY, new
    Integer("1"));
    
    where m_mqProperties is a Hashtable used when creating the
    MQQueueManager object.
    

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    This issue affects users of WebSphere MQ Java/Java Message
    Service (JMS) based applications who utilise connection sharing
    
    Platforms affected:
     All Distributed (iSeries, all Unix and Windows) +Java
    ****************************************************************
    PROBLEM SUMMARY:
    A small timing window in the WebSphere MQ Java/JMS client
    allowed a connection to be identified as suitable for sharing by
    one thread, but then be closed by another thread.
    
    The code was modified to removing this timing window, and also
    prevent the ConcurrentModificationException exception from
    occurring.
    

Problem conclusion

  • The WebSphere MQ Java/JMS client has been updated to remove the
    timing window.
    
    | MDVPARTL 7.0.1-WS-MQ-Windows-FP0001        |
    | MDVPARTL 7.0.1-WS-MQ-SolarisX64-FP0001     |
    | MDVPARTL 7.0.1-WS-MQ-SolarisSparc64-FP0001 |
    | MDVPARTL 7.0.1-WS-MQ-LinuxX64-FP0001       |
    | MDVPARTL 7.0.1-WS-MQ-LinuxS390X-FP0001     |
    | MDVPARTL 7.0.1-WS-MQ-LinuxPPC64-FP0001     |
    | MDVPARTL 7.0.1-WS-MQ-LinuxIA32-FP0001      |
    | MDVPARTL 7.0.1-WS-MQ-HpuxPaRISC64-FP0001   |
    | MDVPARTL 7.0.1-WS-MQ-HpuxIA64-FP0001       |
    | MDVPARTL 7.0.1-WS-MQ-AixPPC64-FP0001       |
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
                       v7.0
    Platform           Fix Pack 7.0.1.2
    --------           --------------------
    Windows            U200316
    AIX                U829807
    HP-UX (PA-RISC)    U829678
    HP-UX (Itanium)    U829681
    Solaris (SPARC)    U829806
    Solaris (x86-64)   U829680
    iSeries            tbc_p700_0_1_2
    Linux (x86)        U829677
    Linux (x86-64)     U829676
    Linux (zSeries)    U829682
    Linux (Power)      U829679
    
    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

    IZ65557

  • Reported component name

    WMQ AIX V7

  • Reported component ID

    5724H7221

  • Reported release

    701

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2009-11-19

  • Closed date

    2009-12-23

  • Last modified date

    2010-04-08

  • 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 AIX V7

  • Fixed component ID

    5724H7221

Applicable component levels

[{"Line of Business":{"code":"LOB36","label":"IBM Automation"},"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSFKSJ","label":"WebSphere MQ"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"7.0.1"}]

Document Information

Modified date:
21 April 2021