IT05491: XA transaction start and transaction lookup in the Queue Manager can be slow

APAR status

• Closed as program error.

Error description

• XA transactions generated by WebSphere Application Server can be
  handled slowly by the IBM MQ queue manager.
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users of IBM MQ queue managers that participate in XA
  transactions managed by WebSphere Application Server.
  
  
  Platforms affected:
  AIX, HP-UX Itanium, Linux on Power, Linux on S390, Linux on x86,
  Linux on x86-64, Solaris SPARC, Linux on zSeries, Solaris
  x86-64, Windows, HP-UX PA-RISC
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  IBM MQ uses a hashing algorithm to reduce the length of lists of
  transactions within the queue manager. The algorithm was not
  adequate to deal with the XIDs generated by WebSphere
  Application Server. The hashing algorithm did not distinguish
  adequately between these XIDs, so they all appeared in the same
  list as all other WAS-originated XIDs. Lookups within this list
  became relatively slow, leading to slow queue manager
  performance for operations on transactions.
  

Problem conclusion

• The algorithm has been changed to deal successfully with the
  XIDs generated by WebSphere Application Server, to improve the
  performance of these transactions.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v7.0       7.0.1.14
  v7.1       7.1.0.7
  v7.5       7.5.0.6
  v8.0       8.0.0.3
  
  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:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  WMQ WINDOWS V7

• Fixed component ID

  5724H7220

Applicable component levels

• R701 PSY

     UP