PH23939: LOOP IN IPI4PROC AFTER LABEL REC37 DURING CREATION OF A TRANSACTION INDEX

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• A tight loop is observed in routine IPI4PROC.REC37 when
  processing program-switch transactions. IMS PA handles
  program-switch transactions by using the MSGORGTK and MSGPREFI
  fields from the IMS x'01'and IMS x'03' records to track the
  relationship. It expects the MSGORGTK to be unique, except for
  transactions in a program-switch sequence, which are tracked
  using MSGPREFI to identify the sequence.
  
  The loop is a result of some program-switch sequences which do
  not follow the expected logic:
   - Switches to transactions with an un-related MSGORGTK.
   - Switch transactions with a non-unique MSGORGTK, i.e. it is
     the same as a previous un-related transaction.
  
  The loop is near x'53a' past label REC37 or near x'6224' past
  the IPIIPROC entry point.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of IMS Performance Analyzer V4.4       *
  ****************************************************************
  * PROBLEM DESCRIPTION: Loop during creation of a transaction   *
  *                      index                                   *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  A tight loop is observed in routine IPI4PROC.REC37 when
  processing program-switch transactions. IMS PA handles
  program-switch transactions by using the MSGORGTK and
  MSGPREFI fields from the IMS x'01' and IMS x'03' records
  to track the relationship. It expects the MSGORGTK to be
  unique, except for transactions in a program-switch
  sequence, which are tracked using MSGPREFI to identify
  the sequence.
  
  The loop is a result of some program-switch sequences which
  do not follow the expected logic:
  
     Switches to transactions with an unrelated MSGORGTK,
  
     Switch transactions with a non-unique MSGORGTK, i.e. it is
     the same as a previous unrelated transaction.
  

Problem conclusion

• Additional validation code is added to assist the handling of
  program-switch transactions. MSGORGTK will not be relied upon
  to uniquely link a program-switch chain and the handling of
  the IMS x'37' Syncpoint Message Transfer, which is used in
  calculating switch time, is strengthened by the addition of
  "defensive code" to reduce the incidence of loops resulting
  from incorrectly linked transactions.
  When a mismatched MSGORGTK is encountered a new message
  IPI0150E will be issued, the message will contain the
  Log Sequence Number (LSN) of the IMS x'35' record where the
  mismatch was detected. The job will return with RC=8 to
  indicate that en error condition was encountered.
  

Temporary fix

Comments

• ×**** PE20/08/24 FIX IN ERROR. SEE APAR PH28761  FOR DESCRIPTION
  

APAR Information

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

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

  UI69964

Modules/Macros

•    IPIATRAC IPIGGET  IPIIPROC IPIMSGT  IPISAPAR
  IPI4PROC
  

Fix information

• Fixed component name

  IMS PERF ANALYZ

• Fixed component ID

  5655E1500

Applicable component levels

• R440 PSY UI69964

     UP20/06/16 P F006

Fix is available

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