PH47348: ADD A SMALL DELAY TO AVOID HTTP KEEPALIVE RACES

APAR status

• Closed as program error.

Error description

• Clients may reuse a persistent connection nearly simultaneously
  with the servers closure, resulting in POST failures.
  
  The Keep-Alive header allows the server to communicate its
  KeepAlive settings in terms of whole seconds to the client, but
  the client and server cannot reliably begin counting the
  interval of time at the same time.
  
  Many clients seemingly use a TTL of exactly the number of
  seconds the server advertises, with no fixed interval or factor
  removed to avoid the race.
  The client and server may not be counting
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:  All users of IBM HTTP Server                *
  ****************************************************************
  * PROBLEM DESCRIPTION: Add KeepAliveTimeoutDelay to help avoid *
  *                      keepalive races.                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Add KeepAliveTimeoutDelay to help avoid keepalive races. There
  is
  a 200ms delay by default unless KeepAliveTimeout is already
  configured with millisecond precision.
  

Problem conclusion

• IBM HTTP Server was updated to add KeepAliveTimeoutDelay to  all
  a delay to be configured to help avoid keepalive races.
  
  The fix for this APAR is targeted for inclusion in IBM HTTP Serv
  fix packs 8.5.5.23 and 9.0.5.13. For more information, see
  'Recommended Updates for WebSphere Application Server':
  https://www.ibm.com/support/pages/node/715553
  

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

  IBM HTTP SERVER

• Fixed component ID

  5724J0801

Applicable component levels