IT32295: MQ classes for Java application hangs when using the BINDINGS transport and getting messages with the MQGMO_CONVERT option

APAR status

• Closed as program error.

Error description

• An MQ classes for Java application running on z/OS USS connects
  in binding mode to a queue manager on z/OS. The application
  contains the following code to get messages encoded in coded
  character set (CCSID) 523 from a queue, and convert them into
  UTF-8 (which maps to CCSID 1208):
  
  ....
  q = qmgr.accessQueue(qName, MQConstants.MQOO_FAIL_IF_QUIESCING |
  MQConstants.MQOO_BROWSE);
  final MQGetMessageOptions gmo = new MQGetMessageOptions();
  gmo.options = MQConstants.MQGMO_BROWSE_FIRST | MQConstants.
  MQGMO_CONVERT | MQConstants.MQGMO_NO_WAIT | MQConstants.
  MQGMO_FAIL_IF_QUIESCING;
  final MQMessage msg = new MQMessage();
  msg.characterSet = 1208;
  msg.format = CMQC.MQFMT_STRING;
  q.get(msg, gmo, bufferSize);
  .....
  
  When getting messages that are slightly smaller than the value
  of "bufferSize", the application hangs when issuing the line:
  
  q.get(msg, gmo, bufferSize);
  

Local fix

• n/a
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This issue affects users of the IBM MQ classes for Java who have
  applications that:
  
  - Connect to a queue manager using the BINDINGS transport.
  - And call the method MQDestination.get(MQMessage message,
  MQGetMessageOptions getMessageOptions, int maxMsgSize), passing
  in an MQGetMessageOptions object that specifies the option
  MQGMO_CONVERT and does not specify the option
  MQGMO_ACCEPT_TRUNCATED_MSG.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  When using the MQ classes for Java, every MQMessage object used
  by an application has an internal buffer associated with it.
  This buffer is used to store the bytes representing the message
  payload. If an application calls the method:
  
  MQDestination.get(MQMessage message, MQGetMessageOptions
  getMessageOptions, int maxMsgSize)
  
  then the maximum size of the buffer will be equal to the value
  of the maxMsgSize parameter.
  
  If an MQ classes for Java application:
  
  - Connects to a queue manager using the BINDINGS transport.
  - And calls the MQDestination.get(MQMessage message,
  MQGetMessageOptions getMessageOptions, int maxMsgSize) method,
  passing in an MQGetMessageOptions object that specifies the
  option MQGMO_CONVERT and does not specify the option
  MQGMO_ACCEPT_TRUNCATED_MSG.
  
  the following sequence of events occurs:
  
  - The MQ classes for Java issue an MQGET API call to get the
  message, and store the bytes representing the message payload in
  the buffer.
  - Next, the MQ classes for Java pass the buffer into some
  internal queue manager routines that perform the data
  conversion.
  - The queue manager routines convert the message payload, and
  update the buffer with the new byte sequence.
  - Finally, the MQ classes for Java store the contents of the
  buffer in the MQMessage object.
  
  Now, when performing data conversion, it was possible for the
  number of bytes in the message to increase. If this happened,
  and the size of the converted message was larger than the
  maximum size of the buffer, the internal queue manager routines
  would fail to convert the message and pass:
  
  - Completion code 1 (MQCC_WARNING)
  - and either reason code 2120 (MQRC_CONVERTED_MSG_TOO_BIG) or
  2190 (MQRC_CONVERTED_STRING_TOO_BIG)
  
  back to the MQ classes for Java. The routines would not update
  the buffer, meaning it still contained the unconverted message.
  
  The MQ classes for Java would then get stuck in a loop,
  continually invoking the internal queue manager conversion
  routines passing in the same buffer, which was not large enough
  to hold the converted message.
  

Problem conclusion

• To resolve this issue, the MQ classes for Java have been updated
  so that:
  
  - If an application calls the MQDestination.get(MQMessage
  message, MQGetMessageOptions getMessageOptions, int maxMsgSize)
  method, passing in an MQGetMessageOptions object that specifies
  the option MQGMO_CONVERT and does not specify the option
  MQGMO_ACCEPT_TRUNCATED_MSG.
  - And the internal queue manager conversion routines are unable
  to convert the message, as the number of bytes in the converted
  message is larger than the value of the maxMsgSize parameter
  
  then an MQException containing:
  
  - Completion code 1 (MQCC_WARNING)
  - And either reason code 2120 (MQRC_CONVERTED_MSG_TOO_BIG) or
  2190 (MQRC_CONVERTED_STRING_TOO_BIG)
  
  will be thrown back to the application - the MQ classes for Java
  will not attempt to invoke the internal queue manager conversion
  routines again, which prevents them from getting stuck in a
  loop. In addition to this, the MQMessage object passed into the
  method will be updated to contain the unconverted message data.
  
  This means that the application will be notified of the failure
  to convert the message data, and be able to access the
  unconverted message via the MQMessage object, which matches the
  behaviour documented in the 2120 (0848) (RC2120):
  MQRC_CONVERTED_MSG_TOO_BIG and 2190 (088E) (RC2190):
  MQRC_CONVERTED_STRING_TOO_BIG topics in the IBM MQ sections of
  IBM Knowledge Center. The URIs for these topics in the MQ V9.1.x
  section of IBM Knowledge Center are shown below:
  
  Topic: 2120 (0848) (RC2120): MQRC_CONVERTED_MSG_TOO_BIG
  URI:
  https://www.ibm.com/support/knowledgecenter/en/SSFKSJ_latest/com
  .ibm.mq.tro.doc/q041810_.html
  
  Topic: 2190 (088E) (RC2190): MQRC_CONVERTED_STRING_TOO_BIG
  URI:
  https://www.ibm.com/support/knowledgecenter/SSFKSJ_latest/com.ib
  m.mq.tro.doc/q042320_.html
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.0 LTS   9.0.0.12
  v9.1 LTS   9.1.0.9
  v9.2 LTS   9.2.0.3
  v9.x CD    9.2.3
  
  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:

  PH23534

• 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