IT30371: MQ might return incorrect values for accounting or statistics AverageQueueTime

APAR status

• Closed as program error.

Error description

• In a system using NTP synchronization, the queue manager might
  return a large positive for AverageQueueTime.
  
  Output from amqsmon:
  
  AverageQueueTime: [174025887487825958, 0]
  Other affected attributes:
  
  TimeOnQAvg
  TimeOnQMax
  TimeOnQMin
  
  This problem likely to occur when there is a backward time shift
   in the system time because of NTP synchronization.
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users using accounting and statistics will be affected by this
  problem.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  When there was a backward time shift MQ  then value calculated
  for AverageQueueTime could result in negative delta and after
  conversion to unsigned the value might become a large positive
  value. The statistics code did not correctly account for this
  possibility.
  

Problem conclusion

• MQ accounting and statistics code has been modified to set the
  AverageQueueTime to Maximum if there is a negative time shift.
  
  The APAR IT13006 fixed similar problem for earlier releases in
  the past. The APAR added some additional changes to adjust the
  AverageQueueTime if there is a negative timeshift.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.0 LTS   9.0.0.9
  v9.1 CD    9.1.5
  v9.1 LTS   9.1.0.4
  
  The latest available maintenance can be obtained from
  'WebSphere MQ Recommended Fixes'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
  
  If the maintenance level is not yet available information on
  its planned availability can be found in 'WebSphere MQ
  Planned Maintenance Release Dates'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
  ---------------------------------------------------------------
  

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

  IBM MQ BASE M/P

• Fixed component ID

  5724H7261

Applicable component levels