IZ80413: WEBSPHERE MQ V7 RECEIVES FDC WITH PROBE ID OF CO052000 WHEN USING A SHARECNV VALUE GREATER THAN ZERO FOR SVRCONN CHANNEL

WebSphere MQ V7.0 Fix Pack 7.0.1.4
WebSphere MQ V7.0.1 for i5/OS Fix Pack 7.0.1.4

APAR status

• Closed as program error.

Error description

• When a WebSphere MQ (WMQ) Java Message Service (JMS) client
  sends large messages across a channel using shared
  conversations, the following FDC is seen on the queue manager:
  
  Probe Id          :- CO052000
  Component         :- cciTcpReceive
  Program Name      :- amqrmppa
  Major Errorcode   :- rrcE_BAD_DATA_RECEIVED
  Probe Type        :- MSGAMQ9207
  Probe Description :- AMQ9207: The data received from host
  'hostname (0.0.0.0)' is not valid.
  
  The FDC will also contain the following unique characteristic
  in the "Dump of the Transmission Segment Header" section. The
  first 28 bytes will contain values other than the expected
  'TSHM' eyecatcher as shown below.
  
  0x0000 00000000 00000000 00000000 00000000 ................
  0x0010 00000000 00000000 00000000 5453484D ............TSHM
  
  
  The data expected should look similar to this:
  
  0x0000 5453484D 00007ff4 00000001 00000000 TSHM............
  0x0010 02860000 00000000 00000000 11010000 ................
  
  
  After the FDC is written, the connection will terminate
  and message "AMQ9999: Channel program ended abnormally." will
  be reported in the queue manager error log for the SVRCONN
  channel.
  
  In certain rare cases, this error can result in a corrupted
  message being put to a queue.
  

Local fix

• Set the SHARECNV value to zero (the default value is 10) for
  the affected SVRCONN channel.
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This issue affects users of the WMQ classes for JMS and WMQ
  classes for Java that send large messages over slow networks
  with both shared conversations and heartbeats enabled.
  
  Platforms affected:
  All Distributed (iSeries, all Unix and Windows) +Java
  ****************************************************************
  PROBLEM SUMMARY:
  Two threads, one sending a large messages, and one in a receive
  call were sharing the same conversation.
  
  The sending thread put its data on to a 32k long buffer to be
  passed on to the TCP layer. There was a locking issue with this
  buffer which meant that if the network was slow it was possible
  for another thread to come in and write to the buffer before all
  the original data had been passed to the network layer.
  
  In this case it was the heartbeat packet periodically sent by
  the receiving thread that was written to the buffer before the
  complete buffer could be sent across the network. This was what
  resulted in the message corruption.
  

Problem conclusion

• Locking has been added to ensure that only one thread at a time
  can update the buffer to be sent down to the remote socket.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
                     v7.0
  Platform           Fix Pack 7.0.1.4
  --------           --------------------
  Windows            U200323
  AIX                U835793
  HP-UX (PA-RISC)    U836458
  HP-UX (Itanium)    U836463
  Solaris (SPARC)    U836459
  Solaris (x86-64)   U836465
  iSeries            tbc_p700_0_1_4
  Linux (x86)        U836460
  Linux (x86-64)     U836464
  Linux (zSeries)    U836461
  Linux (Power)      U836462
  
  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 SOL SPARC

• Fixed component ID

  5724H7223

Applicable component levels

• R701 PSY

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