IT40254: Slowdown in distributed queueing and high CPU usage on the receiver queue manager after applying fix for the APAR IT35383

APAR status

• Closed as program error.

Error description

• In a MQ distributed queueing environment with dynamic queue
  configured as destination queues
  on the receiver queue manager, post upgrade to a fixpack which
  contains the fix for the
  APAR IT35383 or after applying fix for IT35383, slowdown might
  be observed when the dynamic queue
  is deleted while the channel is running and MQ processes
  amqrmppa and amqzlaa0 might consume more
  CPU than usual.
  

Local fix

• Reduce Message retry interval and Message retry count or set to
  0
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users using dynamic queues as destination queues in distributed
  queuing environment with
  queues getting deleted often will be mostly affected by this
  issue.
  
  This APAR IT40254 affects the following MQ versions which
  contain the IT35383 change:
  
  v9.1 LTS   9.1.0.10
  v9.2 LTS   9.2.0.5
  v9.x CD    9.2.4
  v9.x CD    9.2.5
  
  A variation of the IT35383 fix was also included in the 9.0.0.13
  fix pack, but this variation does not suffer from the issue
  described here.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  A change introduced by IT35383 in fixing a looping issue caused
  an undesired side effect and resulted in slowdown on the channel
  when the dynamic queue is deleted while the channel is running.
  

Problem conclusion

• MQ channel code has been modified to prevent the side effect of
  the change added by IT35383 to resolve slowdown. This issue is
  applicable to MQ 9.1 and 9.2 only.
  
  The APAR IT35383 contains complete fix for the slowdown issue on
  MQ 9.0 or interim fixes provided for IT35383 on lower MQ
  versions and hence this APAR IT40254 is not applicable to
  versions earlier than 9.1.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.1 LTS   9.1.0.11
  v9.2 LTS   9.2.0.6
  v9.x CD    9.3.0.0
  
  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 MP

• Fixed component ID

  5724H7271

Applicable component levels