PK54610: AFTER A MESSAGE IS BACKED-OUT TO AN MQ QUEUE FOR AN EXCEPTION AND TRANSACTION ROLL-BACK IN MDB, THE MESSAGE ISN'T RE-DELIVERED

Java SDK 1.5 SR8 Cumulative Fix for WebSphere Application Server
Java SDK 1.5 SR8 Cumulative Fix for WebSphere Application Server
Java SDK 1.5 SR10 Cumulative Fix for WebSphere Application Server
6.1.0.31: Java SDK 1.5 SR11 FP1 Cumulative Fix for WebSphere Application Server
6.1.0.33: Java SDK 1.5 SR12 FP1 Cumulative Fix for WebSphere
6.1.0.29: Java SDK 1.5 SR11 Cumulative Fix for WebSphere Application Server
6.1.0.35: Java SDK 1.5 SR12 FP2 Cumulative Fix for WebSphere
6.1.0.37: Java SDK 1.5 SR12 FP3 Cumulative Fix for WebSphere
6.1.0.39: Java SDK 1.5 SR12 FP4 Cumulative Fix for WebSphere Application Server
6.1.0.41: Java SDK 1.5 SR12 FP5 Cumulative Fix for WebSphere Application Server
6.1.0.43: Java SDK 1.5 SR13 Cumulative Fix for WebSphere Application Server
6.1.0.45: Java SDK 1.5 SR14 Cumulative Fix for WebSphere Application Server
6.1.0.47: WebSphere Application Server V6.1 Fix Pack 47
6.1.0.47: Java SDK 1.5 SR16 Cumulative Fix for WebSphere Application Server
Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Sometime in MDB Processing, an exception can happen during the
  execution of the onMessage() method in the Servant region. This
  will cause a roll-back and will send the message back to Queue
  that the MDB was mapped to.
  .
  At this point, the message will be re-delivered to WebSphere and
  the Servant region with attempt to process it again. However,
  an intermittent problem can occur where this re-delivery does
  not occur.
  .
  During instances of this problem, MQ trace showed that after the
  message was sent back to the MQ Queue (mapped to the Listener
  Port), the Control region issued a Browse on the message, but
  the Servant region never issued a Get on the message to consume
  it.
  .
  Here is a Good and Bad case comparison of  this problem :
  
  ** Note that for this particular application, a second queue
  called "backout queue" is used to put messages that were
  delivered the second time. In general the application is free to
  process the re-delivered message however it wants to.
  .
  =Good case=
  1. Start MDB Listener port (mapped to an input queue)
  2. Listener in Control Region (CR) issues Browse
  3. Servant Region (SR) issues Get (receive)
  4. MDB's onMessage() is dispatched, during which an exception
  occurs,
  causing a RollBack condition.
  5. Message is backed out into input queue
  6. CR issues browse again
  7. SR issues get (receive)
  8. MDB's onMessage() method is dispatched again. Since
  JMSXDeliveryCount is 2, application issues Put (send) to a
  backout queue.
  .
  =Bad case=
  1. Start MDB Listener port (mapped to an input queue)
  2. Listener in CR issues Browse
  3. SR issues Get (receive)
  4. MDB's onMessage() is dispatched, during which an exception
  occurs,
  causing a RollBack condition.
  5. Message is backed out into input queue
  6. CR issues browse again
  7. But SR never issues Get (receive)       <==!
  8. message is stacked on the input queue   <==!
  .
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of WebSphere Application Server    *
  *                 V6.0.1 for z/OS who exploit the WebSphere    *
  *                 MQ Messaging Provider on z/OS.               *
  ****************************************************************
  * PROBLEM DESCRIPTION: When a message is attempted to be       *
  *                      redelivered it is ignored but the       *
  *                      WebSphere Application Server.           *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The message is incorrectly ignored as the WebSphere Application
  Server believes the message is a duplicate and not a redelivery.
  

Problem conclusion

• This APAR fixes the problem and allows a redelivered message
  to be consumed.
  
  APAR PK54610 currently targeted for inclusion in Service
  Level (Fix Pack) 6.0.2.25 of WebSphere Application Server V6.0.1
  for z/OS.
  

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:

  PK60372

Fix information

• Fixed component name

  WEBSPHERE FOR Z

• Fixed component ID

  5655I3500

Applicable component levels

• R601 PSY UK32785

     UP08/01/23 P F801

• R610 PSY

     UP

Fix is available

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