IT37481: Poor performance observed with MQIPT under load when running with Trace=1 or higher in the mqipt.conf file

APAR status

• Closed as program error.

Error description

• High latency with a marked increase in transaction times occurs
  in the IPT when running with Trace=1.  Java thread dumps
  captured during the problem show hundreds of threads waiting
  with call stacks like the following:
  
  Java callstack:
    at com/ibm/mq/ipt/logger/ConnectionLogger.logConnection
       (ConnectionLogger.java:453(Compiled Code))
     (entered lock:
       com/ibm/mq/ipt/logger/ConnectionLogger@0x00000000E01E9040,
       entry count: 1)
    at com/ibm/mq/ipt/logger/ConnectionLogger.logConnection
       (ConnectionLogger.java:377(Compiled Code))
    at com/ibm/mq/ipt/logger/ConnectionDetails.
       logDetailsToCaller(ConnectionDetails.java:219
       (Compiled Code))
    at com/ibm/mq/ipt/ServerConnectionThread.run
       (ServerConnectionThread.java:627(Compiled Code))
    at java/lang/Thread.run(Thread.java:820)
  

Local fix

• Disable IPT trace if it is configured in the mqipt.conf file.
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users with a high number of connections starting and stopping
  through the MQIPT who enable MQIPT trace for debugging purposes
  are at risk of encountering this performance problem.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  MQIPT writes to a connection log when starting and stopping a
  connection.  If MQIPT tracing was active to diagnose a problem,
  tracing overhead could slow down the connection logging and
  cause threads in the MQIPT to back up.  In extreme cases, the
  MQIPT could cease handling new connections because most of its
  threads were waiting for access to the connection log.
  

Problem conclusion

• MQIPT has been updated to ensure that its tracing will no longer
  slow down updates to the connection log and cause delays to
  MQIPT threads.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.2 LTS   9.2.0.15
  v9.3 LTS   9.3.0.5
  v9.x CD    9.3.3
  
  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