IT28706: IBM MQ uses excessive memory for isolated bindings connections

APAR status

• Closed as program error.

Error description

• Heap memory usage from amqzsla0 processes increase over time.
  This memory use may eventually cause available memory on the
  system to be exhausted.
  

Local fix

• There are a couple of workarounds:
  1. Use SHARED or FAST bindings.
  2. Restart the queue manager regularly.
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users of isolated bindings who use large messages may encounter
  this problem.	
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  The code used to communicate between applications and the queue
  manager allocates buffers large enough to hold full copies of MQ
  messages.  The design intention is that these buffers are
  resized if a large message is followed by smaller messages but
  the code to do this was incorrect.  In a system which handles a
  lot of large messages, amqzlsa0 processes may be seen to be
  using a large amount of memory.
  

Problem conclusion

• The IBM MQ code has been corrected so that message buffers are
  correctly resized if they are larger than is needed.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v8.0       8.0.0.13
  v9.0 LTS   9.0.0.8
  v9.1 CD    9.1.3
  v9.1 LTS   9.1.0.3
  
  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