PH30714: PORTOPENRETRIES NEEDS TO DO RETRIES FOR HOSTNAME LOOKUP FAILURES

APAR status

• Closed as program error.

Error description

• When the Liberty server is started shortly after TCPIP is
  up,
  there is a timing window where there may not be routes to
  the
  DNS causing a the server's host name to fail to be resolved
  (since the DNS cannot be contacted). In a case like this, if
  the server tries to resolve the host name at a later time,
  the
  host name will resolve successfully. So, the server should
  retry starting the TCP Channel, versus needing to be
  restarted.
  The messages.log will show these errors:
  CWWKO0224E: TCP Channel defaultHttpEndpoint-ssl
  initialization
  failed. The host server_hostname and port server_port could
  not
  be resolved.
  
  APAR PH11895 added portOpenRetries which added retry logic
  for
  bind failures.  But it also needs retry logic for hostname
  lookup failures.
  

Local fix

• start the Liberty Server after TCPIP and other network
  applications like OMPROUTE are fully up
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:  All users of IBM WebSphere Application      *
  *                  Server Liberty                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: Port opening retry logic was expanded.  *
  *                      Retry attempts will be made on hostname *
  *                      lookup failures in addition to bind     *
  *                      failures.                               *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  When a Liberty server is started on some systems (this mainly
  applies to some Z/OS system setups), there could be a timing
  window where the server's host name cannot be resolved due to a
  failure to contact a DNS, in this case the server fails to open
  the port.
  When this happens, the following error will be seen in
  messages.log:
  CWWKO0224E: TCP Channel endpoint_name initialization failed.
  The host server_hostname and port server_port could not be
  resolved.
  In such a case, the server would eventually be able to resolve
  the hostname and open the ports if it tried again later.
  

Problem conclusion

• Port opening retry logic was expanded in Liberty.  Each hostname
  lookup and/or port binding retry attempt will be tried 1 second
  after the previous one, up until the port opens successfully or
  the number of retries has been reached.  To activate this logic
  add the portOpenRetries option to the tcpOptions under the
  httpEndpoint element in server.xml.
  
  The fix for this APAR is currently targeted for inclusion in fix
  pack 20.0.0.12  Please refer to the Recommended Updates page for
  delivery information:
  http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
  

Temporary fix

• Ensure the subsystems which provide port access and DNS services
  is ready.
  

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

  LIBERTY PROF -

• Fixed component ID

  5655W6514

Applicable component levels