IV23924: WMQ V7 CONNECTION LEAK WHEN USING JMS APPLICATION WITH XA AND QUEUE MANAGER GROUPS WITHIN A CCDT

WebSphere MQ V7.5 Fix Pack 7.5.0.1
WebSphere MQ V7.0 Fix Pack 7.0.1.10
Fix Pack 7.1.0.3 for WebSphere MQ V7.1

APAR status

• Closed as program error.

Error description

• A WebSphere Application Server is using the WebSphere MQ V7
  Resource Adapter, configured to use an Activation Specification
  with XA transactions, and using a CCDT, which controls which
  queue manager the activation spec will connect to.
  
  When the CCDT contains queue manager groups or multiple queue
  manager entries, the activation specification may connect to
  different queue managers. If the deployed MDB driven from that
  activation specification is configured to run under an XA
  transaction, an XAException will be thrown, resulting in the
  failure for the MDB to pick up any available messages on
  the Destination.
  
  This exception is of the form:
  
  (JmqiXAResource) [:/9e66603] Tracing exception:
  javax.transaction.xa.XAException: The method 'xa_open' has
  failed with errorCode '-5'.
  at
  com.ibm.mq.jmqi.JmqiXAResource.<init>(JmqiXAResource.java:220)
  at
  com.ibm.mq.jmqi.JmqiXAResource.getInstance(JmqiXAResource.java:
  104)
  at
  com.ibm.mq.jmqi.JmqiEnvironment.newJmqiXAResource(JmqiEnvironme
  nt.java:1592)
  at
  com.ibm.msg.client.wmq.internal.WMQXASession.<init>(WMQXASessio
  n.java:88)
  at
  com.ibm.msg.client.wmq.internal.WMQXAConnection.createXASession
  (WMQXAConnection.java:95)
  at
  com.ibm.msg.client.jms.internal.JmsXAConnectionImpl.createXASes
  sion
  
  The XA exception that causes the leaking of TCP connections is:
  
  
  After a number of attempts have been made to consume messages
  from the Destination and this exception has been thrown many
  times, it is observed that the queue manager's channel
  'MAXCHANNEL' limit being reached, and no further connections
  on this channel can be established.
  

Local fix

• Local Fix￘
   Do not use XA transactions with qmanagers defined in a
  qmanager group inside of CCDT.
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This issue affects users of the WebSphere MQ classes for JMS,
  who are making use of XA transactions, including:
  
  - The WebSphere MQ V7 classes for JMS.
  - The WebSphere MQ V7 Resource Adapter.
  - The WebSphere Application Server V7 WebSphere MQ messaging
  provider.
  - The WebSphere Application Server V8 WebSphere MQ messaging
  provider.
  - The WebSphere Application Server V6.1 WebSphere MQ messaging
  provider who have configured the WebSphere variable
  MQ_INSTALL_ROOT to point to a WebSphere MQ V7 installation.
  
  Platforms affected:
  All Distributed (iSeries, all Unix and Windows) +Java +Java zOS
  ****************************************************************
  PROBLEM SUMMARY:
  An Object of the class:
  
  com.ibm.msg.client.wmq.internal.WMQXASession
  
  is instantiated whenever a call is made to createXASession() on
  an WebSphere MQ JMS XA Connection object.
  
  During the creation of this WMQXASession object, a call is made
  to the XA resource (the queue manager) to perform an xa_open
  operation.  In the event of a non xa_ok return code, for
  example the invalid configuration where a CCDT is being used
  with queue manager groups, the WMQXASession will fail during
  creation.  However an underlying TCP connection was created as
  part of this xa_open, and was not closed when the failure
  exception was thrown during the creation of the WMQXASession.
  
  This resulted in a leak of a TCP connection each time the
  XAException was thrown.  Depending on which resource ran out
  first, the JVM resources or the queue manager channel limit,
  this leak would eventually be externally observed as
  java.lang.OutOfMemoryError, or the 'MAXCHANNEL' limit being
  reached.
  

Problem conclusion

• The code change associated with this APAR fixes the issue by
  ensuring that the TCP connection associated with the
  WMQXASession is closed after a failure in the xa_open call
  during the WMQXASession creation.
  
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
                     v7.0
  Platform           Fix Pack 7.0.1.10
  --------           --------------------
  Windows            U200352
  AIX                U853055
  HP-UX (PA-RISC)    U853082
  HP-UX (Itanium)    U853087
  Solaris (SPARC)    U853083
  Solaris (x86-64)   U853089
  iSeries            7.0.1.10
  Linux (x86)        U853084
  Linux (x86-64)     U853088
  Linux (zSeries)    U853085
  Linux (Power)      U853086
  zOS                7.0.1.10
  
                     v7.1
  Platform           Fix Pack 7.1.0.3
  --------           --------------------
  Windows            7.1.0.3
  AIX                7.1.0.3
  HP-UX (Itanium)    7.1.0.3
  Solaris (SPARC)    7.1.0.3
  Solaris (x86-64)   7.1.0.3
  iSeries            7.1.0.3
  Linux (x86)        7.1.0.3
  Linux (x86-64)     7.1.0.3
  Linux (zSeries)    7.1.0.3
  Linux (Power)      7.1.0.3
  zOS                7.1.0.3
  
  Platform           v7.5
  --------           --------------------
  Multiplatforms     7.5.0.1
  
  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 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

• R700 PSY

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