IT22694: MQ Java client memory leak when using HTTP URLs for Client Channel Definition Tables (CCDTs)

APAR status

• Closed as program error.

Error description

• An IBM MQ classes for JMS or classes for Java application,
  configured to use a client channel definition table (CCDT)
  referenced using a non-file protocol URL such as http or ftp,
  creates and disconnects connections repeatedly.  After enough
  repetitions a java.lang.OutOfMemory error occurs reporting an
  exhaustion of Java heap memory.
  
  When using a file URL, the same application that creates and
  closes connections repeatedly does not result in a
  java.lang.OutOfMemory error being thrown by the JVM.
  

Local fix

• Use a client channel definition table (CCDT) on a file system
  local to where the application is running such that the file
  protocol can be used in the URL referencing the CCDT.
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This issue affects users of the:
  
    - IBM MQ classes for JMS
    - IBM MQ classes for Java
    - IBM MQ JCA Resource Adapter
  
    - WebSphere Application Server MQ messaging provider
  
  with applications that create and close multiple connections
  during its lifetime using a client channel definition table
  (CCDT) that is stored on a different system from the one on
  which the application is running.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  When an application requested a new connection using a client
  channel definition table (CCDT) that was stored on a different
  system from the one on which the application was running, the
  CCDT would be read and parsed for each connection request.  This
  was because the parsed contents of the CCDT were only cached if
  the CCDT file is local to the application and referenced using
  the "file" protocol in a URL, for example:
  
    java.net.URL chanTab1 = new
  URL("file:///home/admdata/ccdt1.tab");
    factory.setCCDTURL(chanTab1);
  
  where "factory" is an MQConnectionFactory object.
  
  Each time the CCDT was read, a new internal CCDT object was
  created to represent the CCDT file.  The channel definitions
  that were parsed from the CCDT were then stored within a
  java.util.HashMap keyed against the CCDT object created.
  
  The CCDT object created for each read of the CCDT file would not
  be equal to any previously created CCDT objects.  As such, when
  the channel definitions from the CCDT were added to the
  java.util.HashMap using the CCDT object, it did not replace the
  previous cached entry with the newly parsed channel definitions
  and the size of the java.util.HashMap grew.
  
  The old CCDT and channel definition references were not then
  removed from the java.util.HashMap cache.
  
  This processing occurred within the Java MQI layer.
  

Problem conclusion

• The Java MQI has been updated such that if a client channel
  definition table (CCDT) is parsed multiple times, any previously
  cached references to the CCDT or the channel definitions it
  contained, are removed from the relevant internal
  java.util.HashMap collections.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.0 CD    9.0.5
  v9.0 LTS   9.0.0.9
  
  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

  IBM MQ BASE M/P

• Fixed component ID

  5724H7261

Applicable component levels

• R903 PSY

     UP