PI25682: DSNL511I DSNLIENO TCP/IP CONVERSATION FAILED SOCKET=CLOSE RETURN CODE=113 REASON CODE=0523011C

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• DB2DDF DB2TCPIP defect pi25682 dpi25682
  DSNL511I message with indicated return code and reason code on a
  DB2 11 for z/os server system may occur. It is possible for
  the messages to occur at a high rate on some systems.
  
  Example:
  (the location, ipaddr and port will contain valid values, the
  message below is a sample only)
  
  DSNL511I   DSNLIENO TCP/IP CONVERSATION FAILED
             TO LOCATION ....
             IPADDR=....  PORT=....
             SOCKET=CLOSE RETURN CODE=113 REASON CODE=0523011C
  
  The return code=113 and reason code=0523011C indicate a possible
  second close may be occuring after the socket is already
  closed.
  
  
  Additionally, DSNL511I with SOCKET=CLOSE
  RETURN CODE=112 REASON CODE=05230138  may also be seen.
  
  ***************************************************************
  Additional Symptoms and Keywords:
   DSNL511I MSGDSNL511I DSNLIENO
    SOCKET=CLOSE CLOSE
     RETURN CODE=112  REASON CODE=05230138 RC112  112  05230138
     RETURN CODE=113  REASON CODE=0523011C RC113  113  0523011C
    SOCKET=SENDMSG SENDMSG
     RETURN CODE=113  REASON CODE=111D011C RC113  113  111D011C
    SOCKET=READ READ
     RETURN CODE=1121 REASON CODE=74520442 RC1121 1121 74520442
     RETURN CODE=113  REASON CODE=1123011C RC113  113  1123011C
     RETURN CODE=0    REASON CODE=00000000 RC000  000  00000000
    SOCKET=RECV RECV
     RETURN CODE=113  REASON CODE=1179011C RC113  113  1179011C
   DSNL405I MSGDSNL405I
   DSNL415I MSGDSNL415I
   DSNL412I MSGDSNL412I
   DSNL425I MSGDSNL425I
   DSNL031I MSGDSNL031I DSNLZDJN 00D35102 RC00D35102 DSNLZRPA0102
   DSNL031I MSGDSNL031I DSNLZDJN 00D35116 RC00D35516 DSNLZRPA0116
   DSNV417I MSGDSNV417I
   ABEND04E AB04E S004E 04E
    04E-00D3440B 00D3440B RC00D3440B
     DSNLXSRX DSNLXSRX:0019 0019 ABNDID0019 ABID0019 VRADC0019
    04E-00D34412 00D34412 RC00D34412
     DSNLXRBT DSNLXRBT:000A 000A ABNDID000A ABID000A VRADC000A
    04E-00D34424 00D34424 RC00D34424
     DSNLXRAX DSNLXRAX:000A 000A ABNDID000A ABID000A VRADC000A
    04E-00D30014 00D30014 RC00D30014
     DSNLTRSI
      DSNLTRSI+1C60 1C60 OFFSET1C60
      DSNLTRSI+1C64 1C64 OFFSET1C64
      DSNLTRSI+1C8E 1C8E OFFSET1C8E
   ABEND0C4 AB0C4 S00C4 0C4
    0C4-00000004 00000004 RC00000004
     DSNLZRPY DSNLZRPY+27E2 27E2 OFFSET27E2
    0C4-00000010 00000010 RC00000010
     DSNLZTRC DSNLZTRC+16BA 16BA OFFSET16BA
     DSNXROHB DSNXROHB+02CA 02CA OFFSET02CA
    0C4-00000038 00000038 RC00000038
     DSNLZTRC DSNLZTRC+1030 1030 OFFSET1030
   SQLCODE -30081 SQLCODE30081 SQL30081N
  

Local fix

• no local fix or workaround
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All Distributed Data Facility (DDF) users.   *
  *                 DB2 11 for z/OS only.                        *
  ****************************************************************
  * PROBLEM DESCRIPTION: Various DSNL511I message conditions     *
  *                      and other unpredictable symptoms        *
  *                      related to unexpected socket close      *
  *                      conditions.                             *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Relative to DB2 server processing, DB2 11 for z/OS includes the
  following two enhancements:
  1. A performance improvement that is achieved by utilizing
     TCP/IP Synchronous, as opposed to Asynchronous, Receive
     operations while the server thread (DBAT) is processing an
     active transaction.
     This utilization of Synchronous Receive operations (while in
     an active transaction) requires that DB2 also utilize TCP/IP
     "MsgConnTerm" exit support so DB2 can be made aware of
     connection termination events in which case it may be
     necessary to interrupt the DBAT.
  2. A completion of connection termination processing in
     situations where connection termination processing happens
     to be interrupted.
  The combination of these two enhancements leads to a condition
  where a DBAT may be incorrectly interrupted when it is not
  necessary and, as a result of this (unnecessary) interruption,
  then repeat a close of a socket that was already successfully
  closed prior to the DBAT being interrupted.
  This leads to a situation where a DBAT may close a socket that
  has already been closed or, worse, has since been assigned to
  another (requester or server related) thread.  This leads to
  various unexpected DSNL511I messages and other unpredictable
  symptoms that can occur as a result of unexpected socket close
  conditions that appear to be randomly generated.
  The condition appears to be prevalent relative to connections
  with remote DB2 for z/OS partners, and this is due to the use
  of DRDA two phase commit support which tends to lead to an
  abundance of unnecessary DBAT interruption conditions.
  The conditions may also appear to occur after z/OS 1.13
  maintenance (see APARs PM80004 and OA39810), or migration to
  z/OS 2.1, due to the MsgConnTerm support that now becomes
  available to DB2 11 for z/OS.
  Symptoms may be unpredictable but the following symptoms have
  been observed at, either or both, the DB2 11 for z/OS server
  and remote (usually also DB2 for z/OS) requester partners:
  . Message DSNL511I Socket  Return Code Reason Code
                     CLOSE    113        0523011C
                     CLOSE    112        05230138
                     SENDMSG  113        011D011C
                     READ       0        00000000
                     READ    1121        74520442 or 76650446
  . SQLCODE -30081.
  . Hung inactive connection or DBAT, as observed in the Display
    Thread Inactive command report.
  . Message DSNL425I.
  . Message DSNL405I and an unexpected entry in the Display
    Thread Indoubt command report.  The indoubt thread should be
    automatically resolved as indicated by a DSNL415I message.
  . Message DSNL406I and an unexpected entry in the Display
    Thread Indoubt command report.  The indoubt thread should be
    automatically resolved as indicated by a DSNL423I message.
  . An increase in LOGREC entries describing 04E-00E50013 abend
    (interruption) conditions.
  Most symptoms occur relative to the failing DB2 11 for z/OS
  server system in which case the APAR solution can be applied
  at the DB2 11 for z/OS system where the symptom occurs.  But
  due to the nature of the error, it's difficult to be certain
  of the origin (server or requester system) of the error.  As
  a result, the best approach is to apply the APAR solution to
  the system reporting the symptom, if DB2 11 for z/OS, and any
  DB2 11 for z/OS partner(s).
  

Problem conclusion

• DB2 11 for z/OS is changed to:
  1. eliminate the unnecessary interruption of a DBAT as a result
     of "MsgConnTerm" exit processing, and
  2. eliminate the potential of a duplicate socket close
     condition.
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UI21918

Modules/Macros

•    DSNLCTRC DSNLIDDC DSNLIXIT
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RB10 PSY UI21918

     UP14/10/17 P F410 Ž

Fix is available

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