PM73229: THREADS BOTTLENECK IN WMQJMSRAMANAGEDCONNECTIONFACTORY

8.5.0.2: WebSphere Application Server V8.5 Fix Pack 2
8.0.0.6: WebSphere Application Server V8.0 Fix Pack 6
7.0.0.29: WebSphere Application Server V7.0 Fix Pack 29
8.0.0.7: WebSphere Application Server V8.0 Fix Pack 7
8.0.0.8: WebSphere Application Server V8.0 Fix Pack 8
7.0.0.31: WebSphere Application Server V7.0 Fix Pack 31
7.0.0.33: WebSphere Application Server V7.0 Fix Pack 33
8.0.0.9: WebSphere Application Server V8.0 Fix Pack 9
7.0.0.35: WebSphere Application Server V7.0 Fix Pack 35
8.0.0.10: WebSphere Application Server V8.0 Fix Pack 10
7.0.0.37: WebSphere Application Server V7.0 Fix Pack 37
8.0.0.11: WebSphere Application Server V8.0 Fix Pack 11
7.0.0.39: WebSphere Application Server V7.0 Fix Pack 39
8.0.0.12: WebSphere Application Server V8.0 Fix Pack 12
7.0.0.41: WebSphere Application Server V7.0 Fix Pack 41
8.0.0.13: WebSphere Application Server V8.0 Fix Pack 13
7.0.0.43: WebSphere Application Server V7.0 Fix Pack 43
8.0.0.14: WebSphere Application Server V8.0 Fix Pack 14
7.0.0.45: WebSphere Application Server V7.0 Fix Pack 45
8.0.0.15: WebSphere Application Server V8.0 Fix Pack 15
7.0.0.29: Java SDK 1.6 SR13 FP2 Cumulative Fix for WebSphere Application Server
7.0.0.45: Java SDK 1.6 SR16 FP60 Cumulative Fix for WebSphere Application Server
7.0.0.31: Java SDK 1.6 SR15 Cumulative Fix for WebSphere Application Server
7.0.0.35: Java SDK 1.6 SR16 FP1 Cumulative Fix for WebSphere Application Server
7.0.0.37: Java SDK 1.6 SR16 FP3 Cumulative Fix for WebSphere Application Server
7.0.0.39: Java SDK 1.6 SR16 FP7 Cumulative Fix for WebSphere Application Server
7.0.0.41: Java SDK 1.6 SR16 FP20 Cumulative Fix for WebSphere Application Server
7.0.0.43: Java SDK 1.6 SR16 FP41 Cumulative Fix for WebSphere Application Server

APAR status

• Closed as program error.

Error description

• Under high load using WebSphere Application Server with
  WebSphere MQ, poor performance can be observed when JMS
  Connections are rapidly and concurrently created.  A javacore
  reveals threads blocking during the create connection phase.
  
  Examples of threads suffering from the performance problems are:
  
  "thead name" J9VMThread:0x00000000,
  j9thread_t:0x490F6F08, java/lang/Thread:0x00000000, state:B,
  prio=5
  (native thread ID:0x3268, native priority:0x5, native
  policy:UNKNOWN)
  Java callstack:
  at
  com/ibm/ejs/j2c/FreePool.createManagedConnectionWithMCWrapper(Fr
  eePool.java:2034)
  at
  com/ibm/ejs/j2c/FreePool.createOrWaitForConnection(FreePool.java
  :1711(Compiled Code))
  at
  com/ibm/ejs/j2c/PoolManager.reserve(PoolManager.java:2471(Compil
  ed Code))
  at
  com/ibm/ejs/j2c/ConnectionManager.allocateMCWrapper(ConnectionMa
  nager.java:1059(Compiled Code))
  at
  com/ibm/ejs/j2c/ConnectionManager.allocateConnection(ConnectionM
  anager.java:696(Compiled Code))
  at
  com/ibm/ejs/jms/JMSQueueConnectionFactoryHandle.createQueueConne
  ction(JMSQueueConnectionFactoryHandle.java:84(Compiled Code))
  ...
  
  In any example of a javacore the root of the bottleneck will
  be a thread owning the monitor of the
  WMQJMSRAManagedConnectionFactory class.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:  All users of IBM WebSphere Application      *
  *                  Server and WebSphere MQ JMS                 *
  ****************************************************************
  * PROBLEM DESCRIPTION: Performance bottleneck caused by        *
  *                      WMQJMSRAManagedConnectionFactory        *
  *                      class.                                  *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The WMQJMSRAManagedConnectionFactory class used the 'this'
  lock when creating connections to the Queue Manager.  Creating
  a connection over a network is a relatively expensive
  operation and so that lock introduces a signficant bottleneck.
  

Problem conclusion

• The fix for this APAR reduces the impact of the locking by
  introducing three new locks to provide granularity and reduced
  contention for the 'this' lock.  It also utilises volatile to
  avoid the need for synchronization in the majority of cases.
  
  The fix for this APAR is currently targeted for inclusion in
  fix pack 7.0.0.29, 8.0.0.6 and 8.5.0.2.  Please refer to the
  Recommended Updates page for delivery information:
  
  http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
  

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

  WEBS APP SERV N

• Fixed component ID

  5724H8800

Applicable component levels

• R700 PSY

     UP

• R800 PSY

     UP

• R850 PSY

     UP