IBM Thread and Monitor Dump Analyzer for Java




Jinwoo Hwang


Welcome to IBM Thread and Monitor Dump Analyzer for Java. IBM Thread and Monitor Dump Analyzer for Java allows you to find deadlock, possible hung threads and resource contention through its heuristic engine and analysis of the Javacore.




On some platforms, and in some cases, Javacore is known as �Javadump�. The code that creates Javacore is part of the JVM. You can control it by using environment variables and runtime switches. Javacore contains diagnostic information related to the JVM and a Java application captured at a point during execution. For example, the information can be about the operating system, the application environment, threads, native stack, locks, and memory. The exact contents are dependent on the platform on which you are running. By default, a Javacore occurs when the JVM terminates unexpectedly. A Javacore can also be triggered by sending specific signals to the JVM. Although Javacore or Javadump is present in Sun Solaris JVMs, much of the content of the Javacore is IBM value-add; that is, it is present only in IBM JVMs.

IBM Thread and Monitor Dump Analyzer for Java is provided �as-is�.


Location of Javacore file

Operating System

Javacore file name

Format Meaning

Windows and Linux


YYYY=year, MM=month, DD=day, SS=second, PID=processID




PID=processID, TIME=seconds since 1/1/1970








Webcast of IBM Thread and Monitor Dump Analyzer for Java


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How to run IBM Thread and Monitor Dump Analyzer for Java

You need to use the Java 2 Platform, Standard Edition version 6 or higher Java Runtime Environment (JRE) to run IBM Thread and Monitor Dump Analyzer for Java.

Usage <Java path>java �Xmx[heapsize] �jar jca<Thread and Monitor Dump Analyzer for Java version>.jar [javacore files separated by path delimiter] [analysis output HTML file]

Path delimiter on Windows systems is semicolon ;
Path delimiter on Unix systems is colon :

For example,

C:\java\bin\java �Xmx200m �jar jca13.jar

=> Starts IBM Thread and Monitor Dump Analyzer for Java version 1.3 and open javacore files from menu.


/usr/java/bin/java �Xmx200m �jar /usr/jca/jca13.jar /usr/javacore.20060228.171037.2084.txt;/usr/javacore.20060228.171048.2084.txt

=> Starts IBM Thread and Monitor Dump Analyzer for Java version 1.3 with /usr/javacore.20060228.171037.2084.txt and /usr/javacore.20060228.171048.2084.txt


java �Xmx500m �jar jca13.jar  /usr/javacore.20060228.171037.2084.txt;/usr/javacore.20060228.171048.2084.txt output.html

=> Starts IBM Thread and Monitor Dump Analyzer for Java with /usr/javacore.20060228.171037.2084.txt and /usr/javacore.20060228.171048.2084.txt and generates analysis output in output.html without invoking graphical user interface

If there�s java.lang.OutOfMemoryError while you are processing Javacore files, please try increasing the maximum heap size (-Xmx) value to give the JVM more memory.

Maximum heap size should not be larger than the size of available physical memory size for this tool due to performance issue.


1. Start IBM Thread and Monitor Dump Analyzer for Java



The following screen is a snapshot of the initial screen.




2. Select File-> Open Thread Dumps to open Javacore files if you didn�t specify Javacore files in the command line during the startup.


3. You can select multiple Javacore files





4. Loaded Javacore files are listed in the Thread Dump List table.





Thread Dump List provides the following information:



5. Click on a Javacore to display summary of the Javacore.


The following information is displayed for IBM Javacore:



Non-IBM Javacore ( or thread dump ) provides limited information.





6. Click on Right Button of your mouse to bring up a menu.Or click on Analysis menu to display sub menu




7. The following is Thread Detail View of a Javacore:


Threads are sorted by thread name. Thread Detail View provides the following information:







8.If  a thread owns monitors, thread name is marked with a special icon and threads that are waiting for monitor lock are displayed.

In the following example, the thread,Plato priority9, has monitor ownership icon. In waiting threads list, Aristotle and Socrates threads are displayed.




If a thread is waiting for monitor lock, thread name is marked with a special icon and thread that owns monitor lock is displayed.

In the following example, the thread,Aristotle priority5, has waiting for monitor lock icon in name column.

In Blocked by list, Plato priority9 which owns the monitor is displayed:





9. You can sort any column by clicking on table header. The following is Thread Detail View sorted by thread state





10. The following is Thread Detail View sorted by method.





11.Deadlock threads are shown in gray by default as follows:




12. Select multiple Javacore by holding Ctrl key and click on right button of your mouse and select Compare Threads

 Or select Analysis -> Compare Threads to display Compre Threads View




13.  The following is Compre Threads View of two Javacore.

Summary is displayed in the right pane. Thread name and method name are displayed from each Javacore on the table.






Red background indicates there�s possible hang in the thread. Green border indicates runnable thread. Blue border indicates waiting on monitor. Yellow border indicates waiting on condition.


14. Thread summary is displayed when a thread is selected.




15. Select Monitor Detail to display Monitor Detail View






16.    Monitor lock information is displayed in tree format


Total Size is total number of threads directly and indirectly related with a specific monitor.

Size is number of threads directly related with a specific monitor.



Click on one of the threads.



There are 47 threads waiting for the monitor which is locked by Servlet Engine Transports : 3049



Deadlock threads are displayed with the icon, as follows:



17. You can click on any thread to display detailed information about monitor and thread information




18. You can also compare Monitor in Compare Monitor View. Select Compare Monitors Menu




19. Red line indicates there�s possible hang in a specific thread in Compare Monitors View.



If you click on a thread, list of threads waiting for the locks that the thread owns is displayed in the middle pane. If you click on any thread in the middle pane, thread information is displayed on the right pane.


20. Select View-> Option to configure IBM Thread and Monitor Dump Analyzer for Java.



21. You can change default directory, color and other options.



22-1. Select a state in Color and click on Change button to change color.




22-2. Select a color and click on OK




23.In Advanced pane of option , you can customize stack trace pattern recognition engine:


        ID List : ID list of customized stack trace pattern

        ID : Identifier of stack trace pattern. No spaces allowed.

        Stack Name : Stack trace pattern name that is seen from Thread Detail View

        Stack Trace : Stack trace pattern. Syntax : �at package.class.method�.   No parenthesis allowed.

        Description : description of a stack trace pattern

        The tool will search for stack trace pattern and display Stack Name in Thread Detail View if any matching is found

        WARNING : Please reopen thread dumps if new stack trace patterns are added if thread dumps are already loaded.




24. You can delete message in console by selecting Clear Console Menu





25. Select Close Thread Dumps to unload Javacore files.



26. Help menu displays help screen.




27. Select Help->About to display version information of IBM Thread and Monitor Dump Analyzer for Java





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