PH65987: WAS PERFSERVLET JDBC CONNECTION POOL COUNTERS UNEXPECTED RESULTS.

APAR status

• Closed as program error.

Error description

• For the PMI infrastructure, certain stats that are
  "calculated" can be incorrect due to it calculating the data
  on a previous data sample.
  
  For example-> the PercentUsed for thread pool or your J2C/jdbc
  component.
  
  This specifically applies to the calculated stat on the
  "aggregate" level of that stat.
  
  For example:
  
  JDBC/derby
     ConnPool1
         <stats>
     ConnPool2
         <stats>
     ConnPool Aggregate level
     <stats, but aggregation of stats from connPool1 and conPool2>
     ^ It is the calculated stat (i.e., percentused) here that
  is calculated on the previous sample.
  
  
  This can show up as a 0% Percent Used in the aggregate level
  stat when the percent used in the sub/leaf level have values.
  
  The above scenario would occur specifically if the "last sample"
  had percent used of the leaf nodes be 0. Upon a second sample,
  the leaf nodes may have a non-zero value, but the aggregate
  level stat, which is calculating on the previous sample has a
  value of 0.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:  All users of IBM WebSphere Application      *
  *                  Server                                      *
  *                  using PMI                                   *
  ****************************************************************
  * PROBLEM DESCRIPTION: For calculated stats (i.e.              *
  *                      PercentUsed).                           *
  *                      The aggregate level of that stat is     *
  *                      calculated on previous sample.          *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  For calculated stats (i.e. PercentUsed). The value for the stat
  at the aggregate level is calculated on the previous data
  sample.
  

Problem conclusion

• For calculated stats such as "PercentUsed" the value of this
  stat for the aggregate level
  node is calculated on the previous sample.
  
  For example , the following shows the aggregate level stats
  
  Sample 1:
  PoolSize = 5
  FreePool = 5
  PercentUsed = 0
  
  Sample 2:
  PoolSize = 5
  FreePool = 3
  PercentUed = 0 (calculated on Sample 1 information)
  
  The fix for this APAR is targeted for inclusion in fix pack
  9.0.5.24 & 8.5.5.28. For more
  information, see 'Recommended Updates for WebSphere Application
  Server':
  https://www.ibm.com/support/pages/node/715553
  

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:

Fix information

• Fixed component name

  WEBS APP SERV N

• Fixed component ID

  5724H8800

Applicable component levels