How can I view memory usage, thread dump for java programs, from command line?

Question

Is there any known command line tool to ask the JVM to see memory usage and thread dumps of a java program. something like a headless jvisualvm?

Answer 1

You can use jstat to get gc information, jstack to get stack traces and jmap to get memory statistics and memory dumps for off-line inspection.

Answer 2

Ctrl+Break will produce a thread dump and various statistics.

This is documented, along with kill -QUIT, here.

Answer 3

Look into the official debugger, jdb. You have to run your java program with a certain flag, but then you should be able to look at a bunch of stuff from the commandline.