IT15112: MQ channel agent pool process (amqrmppa) memory usage increases over time

APAR status

• Closed as program error.

Error description

• While running MQ 7.5.0.5, the amqrmppa process memory usage
  increases up to 2GB over the course of a day. Over a week,
  the amqrmppa process memory usage increases up to 10GB.
  

Local fix

• The following workarounds may help remedy the issue, they are
  listed in order that will have the least impact on a
  production system:
  .
  1) Disable FASTPATH channels by removing the
      MQIBindType=FASTPATH entry in qm.ini
     .
     Disabling FASTPATH channels will cause a small dip in overall
     performance but this may be a reasonable trade-off for
  stability.
  
  2) Stop using the -x option on strmqm
     .
     The other option is to stop using the -x option on strmqm if
     the production environment can afford to be without the
     multi-instance functionality for a period.
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users of multi-instance queue managers may be affected by this
  issue.  If FASTPATH channels and managed subscriptions are being
  used then the possibility of being affected increases.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  IBM MQ maintains an internal process-wide file handle cache
  which can grow dynamically.  When multi-instance queue managers
  were being used, a coding error introduced a window where memory
  used to grow this cache could be leaked between instances of IBM
  MQ threads.
  

Problem conclusion

• The MQ queue manager code was modified so that the cache space
  allocated by a thread is freed if no other threads are using the
  process-wide file handle cache.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v7.5       7.5.0.8
  v8.0       8.0.0.6
  v9.0 CD    9.0.1
  v9.0 LTS   9.0.0.1
  
  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

  WMQ BASE MULTIP

• Fixed component ID

  5724H7241

Applicable component levels