IT20481: MultiInstance Queue Manager failover may cause .Net client to send duplicate message

APAR status

• Closed as program error.

Error description

• In a .Net client, with the automatic reconnect option ON, if a
  queue manager failover happens when the client is sending
  messages then in some cases a duplicate message is delivered by
  the queue manager.
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users of Managed .Net clients with reconnect option ON which
  connects to a multi instance queue manager.
  
  
  Platforms affected:
  Windows
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  When a Managed .Net client connects to a multi-instance queue
  manager with auto reconnect option specified, then the client
  layer will receive notification when the queue manager fails
  over. If the failover happened while the client was sending a
  non-persistent message and before the reply was received, then
  for non-transacted session, an omission in this logic meant that
  the message was sent twice. Once before the queue manager failed
  over, and for a second time after the client had reconnected.
  

Problem conclusion

• The .Net code has been modified so that, if automatic client
  reconnection occurs while sending a non-persistent message then
  the client will reconnect to the queue manager and:
  - Return from the method normally, if its a non-transacted
  session used to put a non-persistent message.
  - Throw an Exception containing reason code 2003
  (MQRC_BACKED_OUT) from a transacted session.
  - Throw an Exception containing reason code 2549
  (MQRC_CALL_INTERRUPTED) in all other situations.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v8.0       8.0.0.11
  v9.0 LTS   9.0.0.6
  v9.1 CD    9.1.1
  v9.1 LTS   9.1.0.1
  
  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 BASE MULTIP

• Fixed component ID

  5724H7251

Applicable component levels