PM39695: HIGH CPU IN SNMPQE ADDRESS SPACE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• The potential exists for the SNMPQE process to go into a tight
  loop when its limit for the number of open sockets is reached.
  Requests arriving on existing connections will still be
  processed, but no new connections will be serviced.
  

Local fix

• Take one of the following actions.
  
  - Issue a NETSTAT CONN (CLIENT SNMPQEname command to list the
    existing connections and issue a DROP command for one or more
    of them.
  
  - If the majority of connections are from one client, recycle
    that client application.  Investigate why that client is
    creating those connections and correct.
  
  - Recycle the SNMPQE address space.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of the IBM Communications Server   *
  *                 for z/OS Version 1 Release(s) 11, 12,        *
  *                 and 13 IP: SNMP Query Engine (SNMPQE)        *
  ****************************************************************
  * PROBLEM DESCRIPTION: High CPU usage is detected in SNMPQE    *
  *                      address space.                          *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The high CPU in SNMPQE address space occurs when the number of
  open sockets reaches its maximum. This causes the SNMPQE
  process to go into a tight loop due to the listening socket
  staying active but no new connections can be serviced.
  Requests arriving on existing connections will still be
  processed.
  +-------------------------------------------------------------+
  + Please check our Communications Server for OS/390 homepages +
  + for common networking tips and fixes.  The URL for these    +
  + homepages can be found in Informational APAR II11334.       +
  +-------------------------------------------------------------+
  

Problem conclusion

• This apar will address just the high CPU usage since the
  maximum open socket value can not be changed.
  
  SNMPQE code has been modified to avoid the tight loop when
  the maximum number of connections has been reached.
  SNMPQE will not be notified of new connections requests
  until at least one existing connection has closed.
  
  Added new trace messages EZA6409I and EZA6410I which are
  generated in the SNMPQE output file.
  
  ----------------------------------------------------------------
  z/OS Communications Server IP Messages:
  Volume 1 (EZA)
  Document Number SC31-8783
  ----------------------------------------------------------------
  EZA6409I <socket_type> listening socket <socket_value>
  removed from select mask
  
  Explanation:
  The indicated listening socket has been removed from the
  selection mask because the maximum number of sockets are in use.
  While the listening socket is not included in the selection
  mask new connections are not accepted.
  
  <socket_type> indicates whether the listening socket type is
  TCP or IUCV
  <socket_value> indicates the listening socket value
  
  When an existing connection closes, message EZA6410I is
  generated in the output file and new connections can be accepted
  again.
  
  Examples:
  
  EZA6290I Accepted new client connection
  EZA6409I TCP listening socket 5 removed from select mask
  EZA6293I Terminated client connection
  EZA6410I TCP listening socket 5 added back to select mask
  EZA6290I Accepted new client connection
  
  System Action: The SNMP query engine continues processing
  existing connections, but no new connections are accepted for
  this listening socket.
  
  Operator Response: None.
  
  User Response: Not applicable.
  
  System Programmer Response: None
  
  Problem Determination: Not applicable.
  
  Source: z/OS Communications Server TCP/IP: SQESERVE
  
  Module: SQESERV
  
  Routing code: NA
  
  Descriptor code: NA
  
  Automation: Not applicable for automation.
  
  ----------------------------------------------------------------
  EZA6410I <socket_type> listening socket <socket_value>
  added back to select mask
  
  Explanation:
  This message is generated when the listening socket is added to
  the selection mask. Adding the socket to the selection mask
  allows new connections to be accepted for the socket.
  
  <socket_type> indicates whether the listening socket type is
  TCP or IUCV
  <socket_value> indicates the listening socket value
  
  See related message EZA6409I.
  
  Examples:
  
  EZA6290I Accepted new client connection
  EZA6409I TCP listening socket 5 removed from select mask
  EZA6293I Terminated client connection
  EZA6410I TCP listening socket 5 added back to select mask
  EZA6290I Accepted new client connection
  
  System Action: The SNMP query engine continues.
  
  Operator Response: None.
  
  User Response: Not applicable.
  
  System Programmer Response: None
  
  Problem Determination: Not applicable.
  
  Source: z/OS Communications Server TCP/IP: SQESERVE
  
  Module: SQESERV
  
  Routing code: NA
  
  Descriptor code: NA
  
  Automation: Not applicable for automation.
  
  * Cross Reference between External and Internal Names
  EZAAD0B2 (SQESERV )  EZAAD0YN (MSSNMP  )  EZAEA01V (MSSNMP  )
  EZAAD0B2 (SQESERV )  EZAAD0YN (MSSNMP  )  EZAEA01V (MSSNMP  )
  EZAAD0B2 (SQESERV )  EZAAD0YN (MSSNMP  )  EZAEA01V (MSSNMP  )
  

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:

  UK68965 UK68966 UK68967

Modules/Macros

• EZAAD0B2 EZAAD0YN EZAEA01V
  

Fix information

• Fixed component name

  TCP/IP V3 MVS

• Fixed component ID

  5655HAL00

Applicable component levels

• R1B0 PSY UK68965

     UP11/07/26 P F107

• R1C0 PSY UK68966

     UP11/07/26 P F107

• R1D0 PSY UK68967

     UP11/07/26 P F107

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.