IZ35535: LOAD PERFORMANCE PROBLEM ON WINDOWS IF THE CPU PARALLELISM APPLIED IS GREATER THAN 1

DB2 Version 9.5 Fix Pack 5 for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 6a for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 7 for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 8 for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 9 for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 10 for Linux, UNIX, and Windows

APAR status

• Closed as program error.

Error description

• When load cpu_parallelism > 1 is applied on load on the Windows
  platform ( which is the default with a sufficiently sized
  UTIL_HEAP_SZ and a multi CPU machine ), it is possible that
  the load may not have optimal performance.
  
  This is due to a particular spinlock algorithm applied by the
  formatter processes in a load that may suffer from thread
  starvation by the Windows process scheduler.
  
  The problem can be diagnosed with the output of a db2trc
  -perfcount -t data collection, showing excessive wait times in
  the sqlulPutBuffer function call.
  

Local fix

• In some cases the Windows scheduler behaves differently when
  other single process/ multi threaded applications e.g. the
  javaw.exe process started by the Control Center is started. This
  then appears to avoid the thread starvation in the load agents.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * Windows multi cpu environments only                          *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * Load performance problem.                                    *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade the server side to fixpak 5                          *
  ****************************************************************
  

Problem conclusion

• This problem was first fixed in v9.5 fixpak 5
  

Temporary fix

Comments

APAR Information

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

  IZ25650

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

  IC64043

Fix information

• Fixed component name

  DB2 UDB ESE SOL

• Fixed component ID

  5765F4102

Applicable component levels

• R950 PSN

     UP