How do you generate and analyze a thread dump from a running JBoss instance?

Question

How do you generate and analyze a thread dump from a running JBoss instance?

Answer 1

http://java.sun.com/developer/technicalArticles/Programming/Stacktrace/

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"On UNIX platforms you can send a signal to a program by using the kill command. This is the quit signal, which is handled by the JVM. For example, on Solaris you can use the command kill -QUIT process_id, where process_id is the process number of your Java program.

Alternatively you can enter the key sequence <ctrl>\ in the window where the Java program was started. Sending this signal instructs a signal handler in the JVM, to recursively print out all the information on the threads and monitors inside the JVM."

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"Determining the Thread States

You will see many different threads in many different states in a snapshot from a JVM stack trace. The key used is:

R Running or runnable thread

S Suspended thread

CW Thread waiting on a condition variable

MW Thread waiting on a monitor lock

MS Thread suspended waiting on a monitor lock"

Answer 2

There is a JBoss-specific method that is slightly more user-friendly:

http://wiki.jboss.org/wiki/GenerateAThreadDumpWithTheJMXConsole

This is especially useful when you don't have direct access to the host machine (which "kill" would require).

Answer 3

The stacktrace app found here is also useful, especially on Windows machines when the java app is not started from the command line.