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

WebSphere MQ V7.0 Fix Pack 7.0.1.2
WebSphere MQ V7.0.1 for i5/OS Fix Pack 7.0.1.2

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 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

• R701 PSY

     UP