PI33513: EDGE LOAD BALANCER IS OBSERVED USING HIGH CPU

8.5.5.6: WebSphere Application Server V8.5.5 Fix Pack 6
8.0.0.11: WebSphere Application Server V8.0 Fix Pack 11
8.5.5.7: WebSphere Application Server V8.5.5 Fix Pack 7
8.5.5.8: WebSphere Application Server V8.5.5 Fix Pack 8
8.0.0.12: WebSphere Application Server V8.0 Fix Pack 12
8.5.5.9: WebSphere Application Server V8.5.5 Fix Pack 9
8.5.5.10: WebSphere Application Server V8.5.5 Fix Pack 10
8.5.5.11: WebSphere Application Server V8.5.5 Fix Pack 11
8.0.0.13: WebSphere Application Server V8.0 Fix Pack 13
8.5.5.12: WebSphere Application Server V8.5.5 Fix Pack 12
8.0.0.14: WebSphere Application Server V8.0 Fix Pack 14
8.5.5.13: WebSphere Application Server V8.5.5 Fix Pack 13
8.0.0.15: WebSphere Application Server V8.0 Fix Pack 15
8.5.5.14: WebSphere Application Server V8.5.5 Fix Pack 14
8.5.5.15: WebSphere Application Server V8.5.5 Fix Pack 15
8.5.5.17: WebSphere Application Server V8.5.5 Fix Pack 17
8.5.5.20: WebSphere Application Server V8.5.5.20
8.5.5.18: WebSphere Application Server V8.5.5 Fix Pack 18
8.5.5.19: WebSphere Application Server V8.5.5 Fix Pack 19
8.5.5.16: WebSphere Application Server V8.5.5 Fix Pack 16
8.5.5.21: WebSphere Application Server V8.5.5.21

APAR status

• Closed as program error.

Error description

• Edge Load Balancer's advisor does recognize the FIN flag issued
  by backend server, and advisor keeps looking for the flag,
  which causes a loop and high CPU.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:  IBM WebSphere Load Balancer users           *
  ****************************************************************
  * PROBLEM DESCRIPTION: High CPU usage can be observed when     *
  *                      using the http or https advisor.        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  When the http or https advisor is in use and the server
  response does not contain the advisorrequest string nor the
  end of html tag (</HTML>), the advisor code will loop in a
  read call for 21 seconds.
  

Problem conclusion

• Corrected the code to indicate advisorresponse not found when
  the server closes the connection.
  
  IMPORTANT NOTE- If you have keepalive configured on the
  backend servers, you will want to configure the keepalive
  timer to be greater than the advisor interval or the advisor
  will report a false down. A keepalive and connection
  termination (FIN) are signals to the application in the same
  manner. For a default advisor setting, it is recommended to
  set keepalives at a minimum of 20seconds.
  
  Affects both Load Balancers (the LB for ipv4 and LB for ipv4
  and ipv6).
  Fix levels :
  Load Balancer for ipv4 v7.0.0.34
  Load Balancer for ipv4 and ipv6 7.0.0.40
  
  Both Load Balancers 8.0.0.11 and 8.5.5.6
  

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

  WS EDGE LB IPV4

• Fixed component ID

  5724H8812

Applicable component levels

• R800 PSY

     UP

• R850 PSY

     UP