How to get a thread and heap dump of a Java process on Windows that's not running in a console

Question

You can use jmap to get a dump of any process running, assuming you know the pid.

Use Task Manager or Resource Monitor to get the pid. Then

jmap -dump:format=b,file=cheap.hprof <pid>

to get the heap for that process.

You are confusing two different java dumps. kill -3 generates a thread dump, not a heap dump.

Thread dump = stack traces for each thread in the JVM output to stdout as text.

Heap dump = memory contents for the JVM process output to a binary file.

To take a thread dump on Windows, CTRL+BREAK if your JVM is the foreground process is the simplest way. If you have a unix-like shell on Windows like Cygwin or MobaXterm, you can use kill -3 {pid} like you can in Unix.

To take a thread dump in Unix, CTRL+C if your JVM is the foreground process or kill -3 {pid} will work as long as you get the right PID for the JVM.

With either platform, Java comes with several utilities that can help. For thread dumps, jstack {pid} is your best bet. http://docs.oracle.com/javase/1.5.0/docs/tooldocs/share/jstack.html

Just to finish the dump question out: Heap dumps are not commonly used because they are difficult to interpret. But, they have a lot of useful information in them if you know where/how to look at them. The most common usage is to locate memory leaks. It is a good practice to set the -D on the java command-line so that the heap dump is generated automatically upon an OutOfMemoryError, -XX:+HeapDumpOnOutOfMemoryError But, you can manually trigger a heap dump, also. The most common way is to use the java utility jmap.

NOTE: this utility is not available on all platforms. As of JDK 1.6, jmap is available on Windows.

An example command-line would look something like

jmap -dump:file=myheap.bin {pid of the JVM}

The output "myheap.bin" is not human readable (for most of us), and you will need a tool to analyze it. My preference is MAT. http://www.eclipse.org/mat/

I think the best way to create .hprof file in Linux process is with jmap command. For example: jmap -dump:format=b,file=filename.hprof {PID}

In addition to using the mentioned jconsole/visualvm, you can use jstack -l <vm-id> on another command line window, and capture that output.

The <vm-id> can be found using the task manager (it is the process id on windows and unix), or using jps.

Both jstack and jps are include in the Sun JDK version 6 and higher.

I recommend the Java VisualVM distributed with the JDK (jvisualvm.exe). It can connect dynamically and access the threads and heap. I have found in invaluable for some problems.