Identify Java jdwp Debugger Assigned (Ephemeral) Port

Question

I am using the following JVM parameters to start-up a JVM with the hostpot debugger.

-Xdebug -Xrunjdwp:server=y,transport=dt_socket,address=0

Answer 1

Maybe something you could start with.

netstat -tlnp

This gives you a list of all processes listening on a local TCP port. For example:

tcp    0    0 0.0.0.0:35688     0.0.0.0:*     LISTEN   26733/java

35688 - the ephemeral port
java  - the program name which is listening
26733 - the PID of the process 

If you need a finer granularity of the java processes you could use ps to gather informations about the process.

ps x -p 26733

could return something like

26733 pts/1 0:00 java -Xdebug -Xrunjdwp:server=y,transport=dt_socket,address=0 Scratch

Answer 2

From within VM:

    Properties props = sun.misc.VMSupport.getAgentProperties();
    System.out.println(props.getProperty("sun.jdwp.listenerAddress"));

From outside application:

    VirtualMachine vm = com.sun.tools.attach.VirtualMachine.attach(PID);
    try {
        Properties props = vm.getAgentProperties();
        System.out.println(props.getProperty("sun.jdwp.listenerAddress"));
    } finally {
        vm.detach();
    }

Both are not a part of a standard. Applicable only to OpenJDK / Oracle JDK.