PJ40485: MANY ECB'S CAN QUEUE TO INACCESABLE SOCKET

APAR status

• Closed as program error.

Error description

• See Problem Summary.
  

Local fix

• na
  

Problem summary

• APAR NUMBER:  PJ40485
  PRODUCT:  z/TPF
  FUNCTIONAL AREA:  TCP/IP NATIVE STACK
  SHIPPED IN PUT:  10
  
  ABSTRACT:
  Socket monitoring of seckets with ECBs queued to send.
  
  PACKAGE CONTENTS:
  Source Segments:
  (C) base/cp/ctsm.cpy
  (C) base/include/tpf/iusmo.h
  (C) base/include/tpf/i_pwbl.h
  (C) base/macro/ipwbl.mac
  (C) base/macro/isock.mac
  (C) base/macro/iusmo.mac
  (C) base/rt/cmvp.asm
  (C) base/rt/ctfe.asm
  (C) base/rt/cts8.asm
  (C) base/rt/usmo.c
  
  Object Only Binaries:
  None.
  
  Configuration Independent Binaries:
  (C) base/load/CMVP.so
  (C) base/load/CTFE.so
  (C) base/load/CTS8.so
  (C) base/obj/cmvp.o
  (C) base/obj/ctfe.o
  (C) base/obj/cts8.o
  
  Support Files:
  base/lst/cmvp.lst
  base/lst/ctfe.lst
  base/lst/cts8.lst
  base/lst/CMVP.map
  base/lst/CTFE.map
  base/lst/CTS8.map
  
  OTHER BINARIES TO BUILD: YES
  (C) <sys>/load/CPS0.so
  (C) <sys>/load/USMO.so
  (C) <sys>/obj/cctcp3.o
  (C) <sys>/obj/usmo.o
  (C) os390/bin/ppcp.pds
  (C) os390/obj/stpp.o
  
  COMMENTS:
  ECBs queued up to send on a socket can deplete system resources
  to critically low levels. Socket monitoring for high ECB queue
  counts on sockets will allow the customer to use the USMO user
  exit to handle these conditions.
  

Problem conclusion

• SOLUTION:
  This enhancement allows the socket monitor to keep track of the
  number of ECBs that issued a send type API (send(), sendto(),
  write(), and writev()) for a given socket and are queued up
  (suspended) because that socket is blocked. If the number of
  queued ECBs for a given socket reaches certain thresholds
  (threshold values are 10, 25, 50, and 100), the existing socket
  monitor user exit, USMO, will be activated. This allows the
  customer to determine what action to take for the socket (such
  as closing the socket, which would cause all the queued ECBs
  for that socket to be posted so they can go away). Similar to
  other conditions the socket monitor detects, the user exit will
  be called at most once per minute per socket for each threshold
  reached. The user exit is called immediately when the threshold
  is reached. For example, the instant that an 11th ECB becomes
  queued waiting to send on a socket, the user exit will be
  called at the point in time (does not wait for a minute
  boundary to call the exit). Input to the user exit will include
  the condition (send ECBs threshold exceeded), the IP addresses
  and ports of the socket, the file descriptor for the socket,
  and the threshold level just exceeded for this socket. The
  default logic in the user exit is to do nothing.
  
  In addition, the output of the SOCK0043I message, which is the
  normal reply for the 'ZSOCK DISPLAY FORMAT SOCK-xxxxxx'
  command, has been modified with the following additional
  information: the real address of the socket block in memory and
  the current send threshold value along with the current send
  threshold length. A threshold value of 32767 indicates that the
  maximum threshold length of 100 has been exceeded.
  
  COREQS: NO
  None.
  
  MIGRATION CONSIDERATIONS: YES
  Functional, automation, and operation changes:
  SOCK0043I
  
  User exit changes:
  The USMO socket monitor user exit now has another defined
  condition to indicate that one of the send(), sendto(),
  write(), or writev() ECB queue length thresholds has been
  exceeded.  Input to the user exit will include the condition
  (send ECBs threshold exceeded), the IP addresses and ports of
  the socket, the file descriptor of
  the socket, and the threshold value that was just exceeded on
  sends for this socket.  ZNKEY SOCKMON-YES must be entered to
  activate socket monitoring if users would like to have the
  socket monitor user exit called for this condition or any of
  the other previously defined conditions.
  
  
  
  BUILD COMMANDS AND INSTRUCTIONS: YES
  #maketpf commands for linux
  maketpf -f CPS0 cctcp3.o
  maketpf -f USMO usmo.o
  maketpf -f CTS8 cts8.o
  maketpf -f CTFE ctfe.o
  maketpf -f CMVP cmvp.o
  maketpf CPS0 link
  maketpf USMO link TPF_VERIFY_LINK_REFS=NO
  maketpf CTS8 link
  maketpf CTFE link
  maketpf CMVP link
  maketpf USMO link
  #maketpf commands for z/OS
  maketpf -f ppcp stpp.o
  maketpf ppcp link
  
  UPDATED INFORMATION UNITS: YES
  z/TPF Operations
  z/TPF TCP/IP
  
  See your IBM representative if you need additional information.
  
  DOWNLOAD INSTRUCTIONS:
  http://www.ibm.com/software/htp/tpf/maint/maintztpf.html
  
  APAR URL:
  http://www.ibm.com/software/htp/tpf/ztpfmaint/put10/PJ40485.htm
  

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:

Publications Referenced

SK2T8062

Fix information

• Fixed component name

  Z/TPF

• Fixed component ID

  5748T1501

Applicable component levels

• R110 PSY

     UP