IT40467: FDC with Probe Id RM033006 and Message sequence number error AMQ9526E are generated when pipelining is enabled

APAR status

• Closed as program error.

Error description

• When using a sender and receiver channel where pipelining is
  enabled in the qm.ini file, a failure data capture (FDC) record
  with probe ID RM033006 is
  generated along with message sequence number errors in the
  queue manager's error logs.  For example:
  
  Channel pipelining is enabled in qm.ini by setting
  PipeLineLength to a value greater than 1:
  
  Channels:
     PipeLineLength=2
  
  An FDC record with the following information is generated:
  
  Probe Id          :- RM033006
  Application Name  :- MQM
  Component         :- rriReceiveData
  Program Name      :- amqrmppa
  Thread            :- XXXX    DUOWReceive
  QueueManager      :- QUEUE_MANAGER_NAME
  Major Errorcode   :- rrcE_PROTOCOL_ERROR
  Minor Errorcode   :- OK
  Probe Description :- AMQ9504E: A protocol error was detected
  for channel ''.
  
  This FDC header may show that the thread where the error occurs
  is
  tagged as "DUOWReceive" which indicates that the channel is
  using "pipelining".
  
  Also in the queue manager's error logs, there will be message
  sequence number errors:
  
  AMQ9526E: Message sequence number error for channel
  'CHANNEL_NAME'.
  
  EXPLANATION:
  The local and remote queue managers do not agree on the next
  message sequence
  number.  A message with sequence number XXXXXXXX has been sent
  when sequence
  number YYYYYYYY was expected. The remote host is
  'XX.XXX.XXX.XX'.
  ACTION:
  Determine the cause of the inconsistency.  It could be that the
  synchronization
  information has become damaged, or has been backed out to a
  previous version.
  If the situation cannot be resolved, the sequence number can be
  manually reset
  at the sending end of the channel using the RESET CHANNEL
  command.
  
  These message sequence number errors may be accompanied by
  message loss.
  

Local fix

• Turn off channel pipelining by setting PipeLineLength=1 in the
  Channels stanza of the qm.ini file.
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Those using the channel pipelining performance optimisation by
  setting
  PipeLineLength=2 in the Channels stanza of the qm.ini file, and
  who have applied a fix for APAR IT30074.
  
  IT30074 was included in 9.1.0.4 and later LTS fix packs; and in
  9.1.3 CD and later CD releases, including 9.2.0.0.
  
  This issue affects distributed queueing channels over a TCP
  link, which includes automatically defined cluster channel
  pairs, when PipeLineLength=2 is configured.
  
  This APAR does not affect client connections over a SVRCONN
  channel, as the PipeLineLength configuration attribute is not
  applicable to SVRCONN channels.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  A defect introduced by APAR IT30074 meant that, when a network
  slow-down occurred,
  a pipelined receiver channel sent an invalid sequence of
  protocol flows.  These caused
  the sender channel to incorrectly commit a batch of messages
  while the receiver channel
  ended abnormally and backed out the batch.  When the channel
  restarted message
  sequence errors were reported, and in some circumstances
  messages were lost.
  

Problem conclusion

• The defect has been fixed.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.1 LTS   9.1.0.12
  v9.2 LTS   9.2.0.6
  v9.x CD    9.3.0
  
  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

  MQ BASE V9.2

• Fixed component ID

  5724H7281

Applicable component levels