IV71556: HIGH CPU USAGE WITH WEBSPHERE MQ DUE TO NON-XATRANSACTIONS NOT BEING RELEASED FROM THE INTERNAL TRANSACTIONTABLE

APAR status

• Closed as program error.

Error description

• High CPU usage may be reported with WebSphere MQ agents
  processes (amqzlaa0) due to a problem when releasing non-XA
  zombie transactions from the internal transaction table.
  
  A zombie transaction is one that has completed but an
  external reference to the transaction could not be released
  by the application during normal WebSphere MQ syncpoint
  processing.
  The external reference might be caused by runmqsc or other
  monitoring applications that scan the transaction table.
  
   To diagnose this issue do the following at regular intervals.
  
   This documentation captures the increasing non-XA
  transactions. The volume of trace should be monitored to ensure
  that it does not fill the file system.
  
  
   1. amqldmpa -m  -c K -f /var/mqm/errors/kern.txt
   A list of attached connections.
  2. amqldmpa -m  -c A -O2 -f/var/mqm/errors/atm.txt
   A list of the transaction table.
  3. strmqtrc -m  -t detail -p
   where PID= process ID for amqzmuc0
  

Local fix

• Restart the queue manager to provide temporary workaround
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users of WebSphere MQ with utility applications that frequently
  monitor queue manager connections, for example an MQSC script
  which issues DIS CONN(*).
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  A build up of ZOMBIE transactions over an extended period within
  MQ's internal transaction table can cause performance issues and
  degradation of queue manager performance. MQ was not releasing
  the ZOMBIE transactions in a timely manner.
  

Problem conclusion

• WebSphere MQ has been modified to ensure that ZOMBIE
  transactions are correctly released at the earliest appropriate
  moment.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v7.0       7.0.1.14
  v7.1       7.1.0.8
  v7.5       7.5.0.6
  
  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 LIN X86 V7

• Fixed component ID

  5724H7224

Applicable component levels

• R710 PSY

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