How to take thread dumps and heap dumps using java tools

1) To take thread dumps -
Once you have below java options
-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8000
(Note: all tools mentioned below are available in <JAVA_HOME>/bin)

Using jdb
jdb -connect com.sun.jdi.SocketAttach:hostname=localhost,port=8000

> suspend
All threads suspended.
"where all" will give snapshot of all threads.
> where all
http-127.0.0.1-8443-6:
  [1] java.lang.Object.wait (native method)
  [2] java.lang.Object.wait (Object.java:485)
  [3] org.apache.tomcat.util.net.JIoEndpoint$Worker.await (JIoEndpoint.java:416)
  [4] org.apache.tomcat.util.net.JIoEndpoint$Worker.run (JIoEndpoint.java:442)
  [5] java.lang.Thread.run (Thread.java:662)
http-127.0.0.1-8443-5:
  [1] java.lang.Object.wait (native method)
  [2] java.lang.Object.wait (Object.java:485)
  [3] org.apache.tomcat.util.net.JIoEndpoint$Worker.await (JIoEndpoint.java:416)
  [4] org.apache.tomcat.util.net.JIoEndpoint$Worker.run (JIoEndpoint.java:442)
  [5] java.lang.Thread.run (Thread.java:662)
http-127.0.0.1-8443-4:
  [1] java.lang.Object.wait (native method)
  [2] java.lang.Object.wait (Object.java:485)
...
..
to resume all threads.
> resume

Using  jstack -
jstack <jvmid>  (you can get jvmid using jps)

For example -
C:\Documents and Settings\Administrator>jps
4416 Main
5800
3300 Jps
6676

C:\Documents and Settings\Administrator>jstack 4416
2011-12-27 16:32:19
Full thread dump Java HotSpot(TM) Server VM (19.0-b09 mixed mode):

"ajp-127.0.0.1-8009-Acceptor-0" daemon prio=6 tid=0x6fc39c00 nid=0x11fc runnable [0x6d27f000]
   java.lang.Thread.State: RUNNABLE
        at java.net.PlainSocketImpl.socketAccept(Native Method)
        at java.net.PlainSocketImpl.accept(PlainSocketImpl.java:390)
        - locked <0x14495ae0> (a java.net.SocksSocketImpl)

To get thread dump using jboss jmx-console, please go through below link
http://atgkid.blogspot.com/2011/10/how-to-take-thread-dumps-in-jboss.html

2) To take heap dumps - 
Using jmap (available from jdk 1.6 but can also be used on jvm with 1.4+ )
jmap -dump:format=b,file=<filename>.hprof <jvmid>

C:\Documents and Settings\Administrator>jps
4416 Main
5800
3300 Jps
6676

C:\Documents and Settings\Administrator>jmap -dump:format=b,file=sample.hprof 4416
Dumping heap to C:\Documents and Settings\Administrator\sample.hprof ...
Heap dump file created

Using java option -XX:+HeapDumpOnOutOfMemoryError
Once you have above java option, JVM will create heap dump once it is out of memory.

Using  jconsole - Java Monitoring and Management Console - JMX-compliant graphical tool for monitoring a Java virtual machine. It can monitor both local and remote JVMs
To use jconsole you need to have java option "-Dcom.sun.management.jmxremote"

heap dump file will be created in folder from where the application is run. For example - <JBOSS-HOME>/bin or <BEA-DOMAIN-HOME>/bin

Using  jvisualvm - comes with java 1.6 but can be used to visualize/monitor applications running on jdk 1.4 and higher. 

Monitor showing CPU and Heap Usage and total threads and classes. 

To get thread dump you can use

Sample heap dump taken using jvisualvm

To take thread dumps in jvisualvm

Sample Thread dump taken using jvisualvm