PH22727: KEEPALIVE CONNECTIONS MAY BE CLOSED UP TO 100MS EARLY

APAR status

• Closed as program error.

Error description

• This is a flawed optimization in the event MPM to avoid
  frequent wakeups when a timeout event is in the near future (up
  to 100ms).
  

Local fix

• N/A
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:  All users of IBM HTTP Server 9.0 on Linux   *
  *                  and z/OS                                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: Keepalive connections may be closed     *
  *                      by the server up to 100 milliseconds    *
  *                      early.                                  *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Normally IBM HTTP Server informs the client of the keepalive
  timeout it will use via the "Keep-Alive" HTTP response header.
  Some clients may use this exact value to maintain their own
  connection pool lifetimes.  This is already subject to race
  conditions as the server and client will not necessarily be
  counting from down from the same initial time.
  On z/OS and Linux in 9.0 when the "event MPM" is used (default)
  IHS is likely to close keepalive connections close to 100ms
  early due to a flawed optimization.
  Note: IHS 8.5.5 on distributed platforms is not affected.
  IHS 8.5.5 on z/OS is in practice not affected as it is does not
  wake up as frequently to process timeouts.
  

Problem conclusion

• The code was updated to avoid closing keepalive connections
  prematurely.
  
  The fix for this APAR is targeted for inclusion in IBM HTTP
  Server fix pack 9.0.5.4.  For more information,
  see 'Recommended Updates for WebSphere Application Server':
  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

  IBM HTTP SERVER

• Fixed component ID

  5724J0801

Applicable component levels