PM93935: DFSISTS0 MAY APPEAR TO BE LOOP WHEN PROCESSING LONG CHAINS OF MESSAGE SWITCHED TRANSACTIONS.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• DFSISTS0 processing will become very slow when processing long
  chains of message switched transactions and may appear to be
  looping.  In the supplied SLDS file, some Type x'03' records
  show very high message switch counts, such as...
  .
  Field     Value     Description
  --------  ------    ------------------------------------------
  MSGPREFI  65,535    NO. OF PGM-PGM MSG SWITCHES TO GET TO THIS
                      INPUT
           .
           TRAN                : WQSESB
           LOG Sequence Number : 00000000020BAD8F
         -
         Many records show values over 60,000.
  -
  With a sufficient number of these long chains, it may not be
  possible to run DFSISTS0 with some SLDS files.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All IMS V13 users.                           *
  ****************************************************************
  * PROBLEM DESCRIPTION: DFSISTS0 takes a very long time to      *
  *                      complete when processing a log with     *
  *                      a high number of program switches       *
  *                                                              *
  ****************************************************************
  * RECOMMENDATION: INSTALL CORRECTIVE SERVICE FOR APAR/PTF      *
  ****************************************************************
  DFSISTS0 builds a tree to represent message and transaction
  events recorded by the input log file.  Program switches are
  included in the tree as nodes, so logs with high numbers of
  program switches result in very large trees.  The number of
  nodes between the root of the tree and a leaf node can become
  extremely large.  DFSISTS0 was leaving the tree intact
  throughout the time required to process the entire input log,
  so the tree keeps growing as DFSISTS0 works through the log
  data.  Because the tree was being traversed constantly as it
  grew, the time required to reach destination nodes was
  increasing dramatically.  At times, it could appear that
  DFSISTS0 was looping because so much calculation was required
  to find nodes in the tree.
  

Problem conclusion

• GEN:
  POSTREQ PI52261
  KEYWORDS:
  
  *** END IMS KEYWORDS ***
  DFSISTS0 now maintains the internal tree differently.
  Stastics are generated from tree nodes as the log is being
  consumed.  Once the required information has been pulled from
  the input log and statistics can be generated for a particular
  node, the tree can be pruned by removing nodes that are no
  longer needed.  DFSISTS0 continues collecting statistics and
  pruning nodes until all input data has been read.  This prevents
  the tree from becoming so large that it significantly hurts
  performance.
  

Temporary fix

Comments

• REPINNED RP16/04/07 (ATXT) TO ADD POSTREQ PI52261 INFO.
   **** PE16/04/07 PTF IN ERROR. SEE APAR PI52261 FOR DESCRIPTION
  ×**** PE15/11/10 FIX IN ERROR. SEE APAR PI52261  FOR DESCRIPTION
  

APAR Information

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

  PM60852

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

  UK98212

Modules/Macros

•    DFSISTS0
  

Fix information

• Fixed component name

  IMS V13

• Fixed component ID

  5635A0400

Applicable component levels

• R300 PSY UK98212

     UP13/10/08 P F310

Fix is available

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