独立Java应用程序的线程转储

Question

I have a stand-alone java app running on linux + Java 6, which seems to be stuck (no logs being generated) How can i take thread dump of this, without using any other tool (eg. jstack)

Tried below commands, but they are not doing anything

kill -3 <pid>
kill -QUIT <pid>

Am I missing anything ?

Answer 1

You can use Java VisualVM (included in every JDK's bin directory) and connect through JMX. Just add

-Dcom.sun.management.jmxremote.port=PORT
-Dcom.sun.management.jmxremote.ssl=false 
-Dcom.sun.management.jmxremote.authenticate=false

to your JVM startup parameters (at remote host) and enable authentication.

Then start VisualVM (at your client) and add a connection.

See here: http://visualvm.java.net/docindex.html

Answer 2

Get the pid from the jps command (although not necessary).

Did you try with root privileges? If the java process was initiated with root (or daemon) privileges you must take this into account.

# kill -3 <pid>
$ sudo kill -QUIT <pid>

You can also see the threads in the top output by pressing H (not h ).

Then if you identify the stuck you can grab the pid, make hexadecimal and then with the jstack see the stack trace.

Regards.