PH13091: WEBSPHERE PLUG-IN HAS UNEVEN DISTRIBUTION WHEN MULTIPLE SERVERS HAVE A WEIGHT OF 0

9.0.5.2: WebSphere Application Server traditional Version 9.0.5 Fix Pack 2
8.5.5.17: WebSphere Application Server V8.5.5 Fix Pack 17
9.0.5.3: WebSphere Application Server traditional Version 9.0.5 Fix Pack 3

APAR status

• Closed as program error.

Error description

• WebSphere Plug-in cluster iterator does not get updated
  to the correct next member for load balancing
  

Local fix

• N/A
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:  All users of IBM WebSphere Application      *
  *                  Server                                      *
  ****************************************************************
  * PROBLEM DESCRIPTION: Round Robin could pick the same         *
  *                      server for a new request                *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  We found that with a large cluster of servers that has 1/2 of
  them set with a load balance weight of 0, the plugin round
  robin would pick the same server for each new request.
  

Problem conclusion

• A bug was found within the Round Robin algorithym allowing the
  same server selection.  A fix was implemented to correctly
  track the last server picked which provides the correct
  starting point for the next new request.
  
  The fix for this APAR is currently targeted for inclusion in
  fix pack 8.5.5.17 & 9.0.5.2.  Please refer to the Recommended
  Updates page for delivery information:
  http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
  

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

  WEBS APP SERV N

• Fixed component ID

  5724H8800

Applicable component levels

• R850 PSY

     UP

• R900 PSY

     UP