Date Created: Sat 13-Nov-2010

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How to use IBM tools to analyse Javacore files and Java Heapdumps.

These are generated if there is a problem within the JVM. They can also be generated on demand if the relevant environment variables have been set before the JVM is started.

Tools ..

IBM Thread and Monitor Dump Analyzer for Java (JCA)

Installing JCA

To install JCA unzip the jca31.zip file to a directory.
You should have a Windows script file “runjca.cmd”. This script starts the tool.
You may need to edit the script to point at you jvm or to increase/decrease the Max Heap Size (-Xmx500m) setting.

Running JCA

To start the tool either click on the script or run it from a Windows cmd session.



When tool starts you are presented with the following window.



You use either File/Open or click on the

This will display the Open screen. Browse to the directory where the javacore is stored and select it, then click Open.


The tool will show a screen with a progress bar while it loads the javacore.

What it all means




Clicking on the javacore you just loaded in the Thread Dump List


If the tool detected a deadlock then it will be displayed in the lower section of the Thread Dump List.

Selecting the Compare Monitors option from Analysis Menu or clicking
Will show the Deadlocked Threads.


Alternative way of finding Deadlocks in the Javacore.

A search for LKDEADLOCK in the Javacore file using grep or an editor such as vi would also identify the deadlocks

1LKDEADLOCK    Deadlock detected !!!
NULL           ---------------------
NULL          
2LKDEADLOCKTHR  Thread "WebContainer : 3" (0x00000001190A4700)
3LKDEADLOCKWTR    is waiting for:
4LKDEADLOCKMON      sys_mon_t:0x000000011B471160 infl_mon_t: 0x000000011B4711B0:
4LKDEADLOCKOBJ      org/apache/log4j/DailyRollingFileAppender@07000000014CCA58/07000000014CCA70:
3LKDEADLOCKOWN    which is owned by:
2LKDEADLOCKTHR  Thread "WebContainer : 1" (0x00000001179C6500)
3LKDEADLOCKWTR    which is waiting for:
4LKDEADLOCKMON      sys_mon_t:0x00000001156FF760 infl_mon_t: 0x00000001156FF7B0:
4LKDEADLOCKOBJ      org/apache/log4j/spi/RootLogger@0700000001C84A08/0700000001C84A20:
3LKDEADLOCKOWN    which is owned by:
2LKDEADLOCKTHR  Thread "WebContainer : 3" (0x00000001190A4700)
NULL          
NULL          

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Steve Robinson - IBM Champion 2013

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