IZ54623: MQ JAVA AND JMS CLIENT MESSAGE BUFFER NOT REDUCED IF MESSAGES ARE NOT RECEIVED

WebSphere MQ V6.0 Fix Pack 6.0.2.8
WebSphere MQ V6.0 for iSeries Fix Pack 6.0.2.8
WebSphere MQ V7.0 Fix Pack 7.0.1.1
WebSphere MQ V7.0.1 for i5/OS Fix Pack 7.0.1.1
WebSphere MQ V7.0 Fix Pack 7.0.1.2
WebSphere MQ V7.0.1 for i5/OS Fix Pack 7.0.1.2
WebSphere MQ 6.0 for HP OpenVMS Alpha and Itanium - Fix Pack 6.0.2.10 (FP03)

APAR status

• Closed as program error.

Error description

• When receiving messages in either the WebSphere MQ Java or Java
  Message Service (JMS) client, the message buffer is
  automatically increased when needed to accommodate larger
  messages. If the buffer is detected to be too large for 10
  received messages, the buffer size is reduced to prevent
  excessive resource usage.
  
  If 10 messages are not received, and the requests for messages
  return 2033 (MQRC_NO_MSG_AVAILABLE), then the buffer size is not
  reduced. This can result in high Java Garbage collector
  activity.
  

Local fix

• MQ Java client message buffer not reduced if messages are not
  received
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This issue affects users of the WebSphere MQ classes for Java
  and classes for JMS whose applications may process large
  messages followed by small messages at a slow message rate.
  
  Platforms affected:
   All Distributed (iSeries, all Unix and Windows) +Java
  ****************************************************************
  PROBLEM SUMMARY:
  The logic to determine when to reduce the size of the message
  buffer in use did not account for the case when no message was
  received. This meant that the buffer did not reduce as quickly
  as expected.
  

Problem conclusion

• The WebSphere MQ Java and JMS clients now reduce the incoming
  message buffer when either a series of small messages have been
  received, or after a series of 2033 (MQRC_NO_MSG_AVAILABLE)
  return codes, or a combination of both.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
                     v6.0
  Platform           Fix Pack 6.0.2.8
  --------           --------------------
  Windows            U200309
  AIX                U825517
  HP-UX (PA-RISC)    U824678
  HP-UX (Itanium)    U825875
  Solaris (SPARC)    U825511
  Solaris (x86-64)   U825872
  iSeries            tbc_p600_0_2_8
  Linux (x86)        U825181
  Linux (x86-64)     U825874
  Linux (zSeries)    U825516
  Linux (Power)      U825182
  Linux (s390x)      U825873
  
                     v7.0
  Platform           Fix Pack 7.0.1.1
  --------           --------------------
  Windows            U200310
  AIX                U827232
  iSeries            tbc_p700_0_1_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 LIN X86 V6

• Fixed component ID

  5724H7204

Applicable component levels

• R601 PSY

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