PH34252: ULB SLOW TO DETECT SERVERDOWN IF THE OS GOES DOWN.

APAR status

• Closed as program error.

Error description

• Javacores show the Manager thread is waiting for advisor
  processing.
  
  Advisor thread shows a thread with ADV_Base.advise on the
  callstack.
  
  Manager thread shows blocked in MGR_Manager.run
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:  IBM WebSphere Application Server Load       *
  *                  Balancer users                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: The serverDown script does not          *
  *                      execute immediately when a server is    *
  *                      down. Packets are forwarded to an       *
  *                      offline server.                         *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The manager.log (at loglevel 3 or higher) will show these
  messages before the delays occurs:
  MGR: Updating weights to the Executor.
  MGR: bWakeUpNow == true.
  The manager reports will show an advisor load of -1 but the
  weight will be greater than 0.
  

Problem conclusion

• The advisor and manager code uses thread synchronization to
  run concurrently. The advisor code was holding the lock
  mechanism while detecting the server state.
  
  Modified the code such that the advisor does not hold the lock
  while detecting the server state.
  
  Fix levels:
     8.5.5.20
     9.0.5.8
  

Temporary fix

• Delay is reduced if LB's server pings are not disabled (enabled
  by default, java property LB_ADV_NO_PING disables) and advisor
  retries are not configured.
  

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