PH05269: REDUCE NUMBER OF DSNV522I/DSNV523I MESSAGES FOR DSNVDTA

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• PI29671 added the DSNV522I/DSNV523I messages to show the
  latch holders that were boosted when a system agent was waiting
  for the latch for more than 60 seconds.
  PI76356 added DSNV522I/DSNV523I messages when the agent that
  scans for latch holders needing a boost was itself waiting for
  a latch and boosted the latch holder.
  After PI76356, some customers began getting too many DSNV522I
  messages.  The object of this APAR is to adjust the timing of
  the PI76356 boosts and the resulting DSNV522I/DSNV523I messages.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: Db2 for z/OS V11 and V12 users.              *
  ****************************************************************
  * PROBLEM DESCRIPTION: Messages, MSGDSNV522I and MSGDSNV523I,  *
  *                      are issued too frequently when the VMON *
  *                      system agent cannot get a latch.        *
  ****************************************************************
  * RECOMMENDATION: Apply corrective PTF when available.         *
  ****************************************************************
  When the VMON system agent scans to find agents running
  in Db2 that have been waiting for a latch, this VMON system
  agent needs to get latches.  These latches are requested
  repeatedly in a loop until the latch is available.  When the
  first latch request in the loop fails, the priority of the
  agent holding the latch was temporarily boosted and the
  DSNV522I and DSNV523I messages were issued. Since the
  latch request in the loop is a conditional latch request,
  the latch request can fail easily, causing the temporary
  boost and the DSNV522I and DSNV523I messages to be issued.
  

Problem conclusion

• Instead of issuing the temporary boost at the first conditional
  latch failure in the loop, the logic was changed to issue the
  temporary boost after the next to last conditional latch
  request in the loop fails. This give more opportunity for the
  latch request to succeed.  If the latch request succeeds, the
  temporary boost and the corresponding DSNV522I and DSNV523I
  messages are avoided. In addition, tracking logic is added to
  reduce the frequency of the DSNV522I and DSNV523I messages.
  

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:

  UI62077 UI62078

Modules/Macros

•    DSNVDTA
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RB10 PSY UI62078

     UP19/04/06 P F904

• RC10 PSY UI62077

     UP19/04/06 P F904

Fix is available

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